[PATCH rcu 01/23] rcu: Dump rcuc kthread status for CPUs not reporting quiescent state

[PATCH rcu 01/23] rcu: Dump rcuc kthread status for CPUs not reporting quiescent state

[Paul E. McKenney]

From: Zqiang <qiang1.zhang@intel.com>

If the rcutree.use_softirq kernel boot parameter is disabled, then it is
possible that a RCU CPU stall is due to the rcuc kthreads being starved of
CPU time.  There is currently no easy way to infer this from the RCU CPU
stall warning output.  This commit therefore adds a string of the form "
rcuc=%ld jiffies(starved)" to a given CPU's output if the corresponding
rcuc kthread has been starved for more than two seconds.

[ paulmck: Eliminate extraneous space characters. ]

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/tree_stall.h | 49 ++++++++++++++++++-----------------------
 1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 4995c078cff98..3556637768fd5 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -409,7 +409,19 @@ static bool rcu_is_gp_kthread_starving(unsigned long *jp)
 
 static bool rcu_is_rcuc_kthread_starving(struct rcu_data *rdp, unsigned long *jp)
 {
-	unsigned long j = jiffies - READ_ONCE(rdp->rcuc_activity);
+	int cpu;
+	struct task_struct *rcuc;
+	unsigned long j;
+
+	rcuc = rdp->rcu_cpu_kthread_task;
+	if (!rcuc)
+		return false;
+
+	cpu = task_cpu(rcuc);
+	if (cpu_is_offline(cpu) || idle_cpu(cpu))
+		return false;
+
+	j = jiffies - READ_ONCE(rdp->rcuc_activity);
 
 	if (jp)
 		*jp = j;
@@ -434,6 +446,9 @@ static void print_cpu_stall_info(int cpu)
 	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	char *ticks_title;
 	unsigned long ticks_value;
+	bool rcuc_starved;
+	unsigned long j;
+	char buf[32];
 
 	/*
 	 * We could be printing a lot while holding a spinlock.  Avoid
@@ -451,7 +466,10 @@ static void print_cpu_stall_info(int cpu)
 	delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
 	falsepositive = rcu_is_gp_kthread_starving(NULL) &&
 			rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp));
-	pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld %s\n",
+	rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j);
+	if (rcuc_starved)
+		sprintf(buf, " rcuc=%ld jiffies(starved)", j);
+	pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld%s%s\n",
 	       cpu,
 	       "O."[!!cpu_online(cpu)],
 	       "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
@@ -464,32 +482,10 @@ static void print_cpu_stall_info(int cpu)
 	       rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
 	       rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
 	       data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
+	       rcuc_starved ? buf : "",
 	       falsepositive ? " (false positive?)" : "");
 }
 
-static void rcuc_kthread_dump(struct rcu_data *rdp)
-{
-	int cpu;
-	unsigned long j;
-	struct task_struct *rcuc;
-
-	rcuc = rdp->rcu_cpu_kthread_task;
-	if (!rcuc)
-		return;
-
-	cpu = task_cpu(rcuc);
-	if (cpu_is_offline(cpu) || idle_cpu(cpu))
-		return;
-
-	if (!rcu_is_rcuc_kthread_starving(rdp, &j))
-		return;
-
-	pr_err("%s kthread starved for %ld jiffies\n", rcuc->comm, j);
-	sched_show_task(rcuc);
-	if (!trigger_single_cpu_backtrace(cpu))
-		dump_cpu_task(cpu);
-}
-
 /* Complain about starvation of grace-period kthread.  */
 static void rcu_check_gp_kthread_starvation(void)
 {
@@ -662,9 +658,6 @@ static void print_cpu_stall(unsigned long gps)
 	rcu_check_gp_kthread_expired_fqs_timer();
 	rcu_check_gp_kthread_starvation();
 
-	if (!use_softirq)
-		rcuc_kthread_dump(rdp);
-
 	rcu_dump_cpu_stacks();
 
 	raw_spin_lock_irqsave_rcu_node(rnp, flags);
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 02/23] rcu: Apply noinstr to rcu_idle_enter() and rcu_idle_exit()

[Paul E. McKenney]

This commit applies the "noinstr" tag to the rcu_idle_enter() and
rcu_idle_exit() functions, which are invoked from portions of the idle
loop that cannot be instrumented.  These tags require reworking the
rcu_eqs_enter() and rcu_eqs_exit() functions that these two functions
invoke in order to cause them to use normal assertions rather than
lockdep.  In addition, within rcu_idle_exit(), the raw versions of
local_irq_save() and local_irq_restore() are used, again to avoid issues
with lockdep in uninstrumented code.

This patch is based in part on an earlier patch by Jiri Olsa, discussions
with Peter Zijlstra and Frederic Weisbecker, earlier changes by Thomas
Gleixner, and off-list discussions with Yonghong Song.

Link: https://lore.kernel.org/lkml/20220515203653.4039075-1-jolsa@kernel.org/
Reported-by: Jiri Olsa <jolsa@kernel.org>
Reported-by: Alexei Starovoitov <ast@kernel.org>
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Yonghong Song <yhs@fb.com>
---
 kernel/rcu/tree.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c25ba442044a6..9a5edab5558c9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -631,8 +631,8 @@ static noinstr void rcu_eqs_enter(bool user)
 		return;
 	}
 
-	lockdep_assert_irqs_disabled();
 	instrumentation_begin();
+	lockdep_assert_irqs_disabled();
 	trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks));
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	rcu_preempt_deferred_qs(current);
@@ -659,9 +659,9 @@ static noinstr void rcu_eqs_enter(bool user)
  * If you add or remove a call to rcu_idle_enter(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_idle_enter(void)
+void noinstr rcu_idle_enter(void)
 {
-	lockdep_assert_irqs_disabled();
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
 	rcu_eqs_enter(false);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
@@ -861,7 +861,7 @@ static void noinstr rcu_eqs_exit(bool user)
 	struct rcu_data *rdp;
 	long oldval;
 
-	lockdep_assert_irqs_disabled();
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
 	rdp = this_cpu_ptr(&rcu_data);
 	oldval = rdp->dynticks_nesting;
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
@@ -896,13 +896,13 @@ static void noinstr rcu_eqs_exit(bool user)
  * If you add or remove a call to rcu_idle_exit(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void rcu_idle_exit(void)
+void noinstr rcu_idle_exit(void)
 {
 	unsigned long flags;
 
-	local_irq_save(flags);
+	raw_local_irq_save(flags);
 	rcu_eqs_exit(false);
-	local_irq_restore(flags);
+	raw_local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_exit);
 
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 03/23] context_tracking: Remove unused context_tracking_in_user()

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

This function is not used and CT_WARN_ON() coupled with ct_state() is
the preferred way to assert context tracking state values.

Reported-by: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking_state.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index ae1e63e269474..edc7b46376a6b 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -41,12 +41,7 @@ static inline bool context_tracking_enabled_this_cpu(void)
 	return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
 }
 
-static __always_inline bool context_tracking_in_user(void)
-{
-	return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
-}
 #else
-static __always_inline bool context_tracking_in_user(void) { return false; }
 static __always_inline bool context_tracking_enabled(void) { return false; }
 static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
 static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; }
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 04/23] context_tracking: Add a note about noinstr VS unsafe context tracking functions

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Some context tracking functions enter or exit into/from RCU idle mode
while using trace-able and lockdep-aware IRQs (un-)masking. As a result
those functions can't get tagged as noinstr. This is unlikely to be
fixed since these are obsolete APIs. Drop a note about this matter.

[ paulmck: Apply Peter Zijlstra feedback. ]

Reported-by: Peter Zijlstra <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/context_tracking.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 36a98c48aedc7..3082332f64765 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -103,6 +103,15 @@ void noinstr __context_tracking_enter(enum ctx_state state)
 }
 EXPORT_SYMBOL_GPL(__context_tracking_enter);
 
+/*
+ * OBSOLETE:
+ * This function should be noinstr but the below local_irq_restore() is
+ * unsafe because it involves illegal RCU uses through tracing and lockdep.
+ * This is unlikely to be fixed as this function is obsolete. The preferred
+ * way is to call __context_tracking_enter() through user_enter_irqoff()
+ * or context_tracking_guest_enter(). It should be the arch entry code
+ * responsibility to call into context tracking with IRQs disabled.
+ */
 void context_tracking_enter(enum ctx_state state)
 {
 	unsigned long flags;
@@ -125,6 +134,14 @@ void context_tracking_enter(enum ctx_state state)
 NOKPROBE_SYMBOL(context_tracking_enter);
 EXPORT_SYMBOL_GPL(context_tracking_enter);
 
+/*
+ * OBSOLETE:
+ * This function should be noinstr but it unsafely calls local_irq_restore(),
+ * involving illegal RCU uses through tracing and lockdep.
+ * This is unlikely to be fixed as this function is obsolete. The preferred
+ * way is to call user_enter_irqoff(). It should be the arch entry code
+ * responsibility to call into context tracking with IRQs disabled.
+ */
 void context_tracking_user_enter(void)
 {
 	user_enter();
@@ -168,6 +185,15 @@ void noinstr __context_tracking_exit(enum ctx_state state)
 }
 EXPORT_SYMBOL_GPL(__context_tracking_exit);
 
+/*
+ * OBSOLETE:
+ * This function should be noinstr but the below local_irq_save() is
+ * unsafe because it involves illegal RCU uses through tracing and lockdep.
+ * This is unlikely to be fixed as this function is obsolete. The preferred
+ * way is to call __context_tracking_exit() through user_exit_irqoff()
+ * or context_tracking_guest_exit(). It should be the arch entry code
+ * responsibility to call into context tracking with IRQs disabled.
+ */
 void context_tracking_exit(enum ctx_state state)
 {
 	unsigned long flags;
@@ -182,6 +208,14 @@ void context_tracking_exit(enum ctx_state state)
 NOKPROBE_SYMBOL(context_tracking_exit);
 EXPORT_SYMBOL_GPL(context_tracking_exit);
 
+/*
+ * OBSOLETE:
+ * This function should be noinstr but it unsafely calls local_irq_save(),
+ * involving illegal RCU uses through tracing and lockdep. This is unlikely
+ * to be fixed as this function is obsolete. The preferred way is to call
+ * user_exit_irqoff(). It should be the arch entry code responsibility to
+ * call into context tracking with IRQs disabled.
+ */
 void context_tracking_user_exit(void)
 {
 	user_exit();
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 05/23] context_tracking: Rename __context_tracking_enter/exit() to __ct_user_enter/exit()

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

The context tracking namespace is going to expand and some new functions
will require even longer names. Start shrinking the context_tracking
prefix to "ct" as is already the case for some existing macros, this
will make the introduction of new functions easier.

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking.h | 12 ++++++------
 kernel/context_tracking.c        | 20 ++++++++++----------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 7a14807c9d1a6..773035124badb 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -14,8 +14,8 @@
 extern void context_tracking_cpu_set(int cpu);
 
 /* Called with interrupts disabled.  */
-extern void __context_tracking_enter(enum ctx_state state);
-extern void __context_tracking_exit(enum ctx_state state);
+extern void __ct_user_enter(enum ctx_state state);
+extern void __ct_user_exit(enum ctx_state state);
 
 extern void context_tracking_enter(enum ctx_state state);
 extern void context_tracking_exit(enum ctx_state state);
@@ -38,13 +38,13 @@ static inline void user_exit(void)
 static __always_inline void user_enter_irqoff(void)
 {
 	if (context_tracking_enabled())
-		__context_tracking_enter(CONTEXT_USER);
+		__ct_user_enter(CONTEXT_USER);
 
 }
 static __always_inline void user_exit_irqoff(void)
 {
 	if (context_tracking_enabled())
-		__context_tracking_exit(CONTEXT_USER);
+		__ct_user_exit(CONTEXT_USER);
 }
 
 static inline enum ctx_state exception_enter(void)
@@ -74,7 +74,7 @@ static inline void exception_exit(enum ctx_state prev_ctx)
 static __always_inline bool context_tracking_guest_enter(void)
 {
 	if (context_tracking_enabled())
-		__context_tracking_enter(CONTEXT_GUEST);
+		__ct_user_enter(CONTEXT_GUEST);
 
 	return context_tracking_enabled_this_cpu();
 }
@@ -82,7 +82,7 @@ static __always_inline bool context_tracking_guest_enter(void)
 static __always_inline void context_tracking_guest_exit(void)
 {
 	if (context_tracking_enabled())
-		__context_tracking_exit(CONTEXT_GUEST);
+		__ct_user_exit(CONTEXT_GUEST);
 }
 
 /**
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 3082332f64765..e36395598095e 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -51,15 +51,15 @@ static __always_inline void context_tracking_recursion_exit(void)
 }
 
 /**
- * context_tracking_enter - Inform the context tracking that the CPU is going
- *                          enter user or guest space mode.
+ * __ct_user_enter - Inform the context tracking that the CPU is going
+ *		     to enter user or guest space mode.
  *
  * This function must be called right before we switch from the kernel
  * to user or guest space, when it's guaranteed the remaining kernel
  * instructions to execute won't use any RCU read side critical section
  * because this function sets RCU in extended quiescent state.
  */
-void noinstr __context_tracking_enter(enum ctx_state state)
+void noinstr __ct_user_enter(enum ctx_state state)
 {
 	/* Kernel threads aren't supposed to go to userspace */
 	WARN_ON_ONCE(!current->mm);
@@ -101,7 +101,7 @@ void noinstr __context_tracking_enter(enum ctx_state state)
 	}
 	context_tracking_recursion_exit();
 }
-EXPORT_SYMBOL_GPL(__context_tracking_enter);
+EXPORT_SYMBOL_GPL(__ct_user_enter);
 
 /*
  * OBSOLETE:
@@ -128,7 +128,7 @@ void context_tracking_enter(enum ctx_state state)
 		return;
 
 	local_irq_save(flags);
-	__context_tracking_enter(state);
+	__ct_user_enter(state);
 	local_irq_restore(flags);
 }
 NOKPROBE_SYMBOL(context_tracking_enter);
@@ -149,8 +149,8 @@ void context_tracking_user_enter(void)
 NOKPROBE_SYMBOL(context_tracking_user_enter);
 
 /**
- * context_tracking_exit - Inform the context tracking that the CPU is
- *                         exiting user or guest mode and entering the kernel.
+ * __ct_user_exit - Inform the context tracking that the CPU is
+ * 		    exiting user or guest mode and entering the kernel.
  *
  * This function must be called after we entered the kernel from user or
  * guest space before any use of RCU read side critical section. This
@@ -160,7 +160,7 @@ NOKPROBE_SYMBOL(context_tracking_user_enter);
  * This call supports re-entrancy. This way it can be called from any exception
  * handler without needing to know if we came from userspace or not.
  */
-void noinstr __context_tracking_exit(enum ctx_state state)
+void noinstr __ct_user_exit(enum ctx_state state)
 {
 	if (!context_tracking_recursion_enter())
 		return;
@@ -183,7 +183,7 @@ void noinstr __context_tracking_exit(enum ctx_state state)
 	}
 	context_tracking_recursion_exit();
 }
-EXPORT_SYMBOL_GPL(__context_tracking_exit);
+EXPORT_SYMBOL_GPL(__ct_user_exit);
 
 /*
  * OBSOLETE:
@@ -202,7 +202,7 @@ void context_tracking_exit(enum ctx_state state)
 		return;
 
 	local_irq_save(flags);
-	__context_tracking_exit(state);
+	__ct_user_exit(state);
 	local_irq_restore(flags);
 }
 NOKPROBE_SYMBOL(context_tracking_exit);
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 06/23] context_tracking: Rename context_tracking_user_enter/exit() to user_enter/exit_callable()

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

context_tracking_user_enter() and context_tracking_user_exit() are
ASM callable versions of user_enter() and user_exit() for architectures
that didn't manage to check the context tracking static key from ASM.
Change those function names to better reflect their purpose.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 arch/arm/kernel/entry-header.S   |  8 ++++----
 arch/csky/kernel/entry.S         |  4 ++--
 arch/riscv/kernel/entry.S        |  6 +++---
 include/linux/context_tracking.h |  4 ++--
 kernel/context_tracking.c        | 28 +++++++++++++++++-----------
 5 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 5865621bf6912..95def2b38d1ca 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -369,10 +369,10 @@ ALT_UP_B(.L1_\@)
 #ifdef CONFIG_CONTEXT_TRACKING
 	.if	\save
 	stmdb   sp!, {r0-r3, ip, lr}
-	bl	context_tracking_user_exit
+	bl	user_exit_callable
 	ldmia	sp!, {r0-r3, ip, lr}
 	.else
-	bl	context_tracking_user_exit
+	bl	user_exit_callable
 	.endif
 #endif
 	.endm
@@ -381,10 +381,10 @@ ALT_UP_B(.L1_\@)
 #ifdef CONFIG_CONTEXT_TRACKING
 	.if	\save
 	stmdb   sp!, {r0-r3, ip, lr}
-	bl	context_tracking_user_enter
+	bl	user_enter_callable
 	ldmia	sp!, {r0-r3, ip, lr}
 	.else
-	bl	context_tracking_user_enter
+	bl	user_enter_callable
 	.endif
 #endif
 	.endm
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
index a4ababf25e243..bc734d17c16f4 100644
--- a/arch/csky/kernel/entry.S
+++ b/arch/csky/kernel/entry.S
@@ -23,7 +23,7 @@
 	mfcr	a0, epsr
 	btsti	a0, 31
 	bt	1f
-	jbsr	context_tracking_user_exit
+	jbsr	user_exit_callable
 	ldw	a0, (sp, LSAVE_A0)
 	ldw	a1, (sp, LSAVE_A1)
 	ldw	a2, (sp, LSAVE_A2)
@@ -160,7 +160,7 @@ ret_from_exception:
 	cmpnei	r10, 0
 	bt	exit_work
 #ifdef CONFIG_CONTEXT_TRACKING
-	jbsr	context_tracking_user_enter
+	jbsr	user_enter_callable
 #endif
 1:
 #ifdef CONFIG_PREEMPTION
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 2e5b88ca11ce1..12f6bba57e335 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -112,11 +112,11 @@ _save_context:
 #endif
 
 #ifdef CONFIG_CONTEXT_TRACKING
-	/* If previous state is in user mode, call context_tracking_user_exit. */
+	/* If previous state is in user mode, call user_exit_callable(). */
 	li   a0, SR_PP
 	and a0, s1, a0
 	bnez a0, skip_context_tracking
-	call context_tracking_user_exit
+	call user_exit_callable
 skip_context_tracking:
 #endif
 
@@ -270,7 +270,7 @@ resume_userspace:
 	bnez s1, work_pending
 
 #ifdef CONFIG_CONTEXT_TRACKING
-	call context_tracking_user_enter
+	call user_enter_callable
 #endif
 
 	/* Save unwound kernel stack pointer in thread_info */
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 773035124badb..69532cd18f72c 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -19,8 +19,8 @@ extern void __ct_user_exit(enum ctx_state state);
 
 extern void context_tracking_enter(enum ctx_state state);
 extern void context_tracking_exit(enum ctx_state state);
-extern void context_tracking_user_enter(void);
-extern void context_tracking_user_exit(void);
+extern void user_enter_callable(void);
+extern void user_exit_callable(void);
 
 static inline void user_enter(void)
 {
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index e36395598095e..9d4a872ca92c4 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -134,19 +134,22 @@ void context_tracking_enter(enum ctx_state state)
 NOKPROBE_SYMBOL(context_tracking_enter);
 EXPORT_SYMBOL_GPL(context_tracking_enter);
 
-/*
- * OBSOLETE:
- * This function should be noinstr but it unsafely calls local_irq_restore(),
- * involving illegal RCU uses through tracing and lockdep.
+/**
+ * user_enter_callable() - Unfortunate ASM callable version of user_enter() for
+ * 			   archs that didn't manage to check the context tracking
+ * 			   static key from low level code.
+ *
+ * This OBSOLETE function should be noinstr but it unsafely calls
+ * local_irq_restore(), involving illegal RCU uses through tracing and lockdep.
  * This is unlikely to be fixed as this function is obsolete. The preferred
  * way is to call user_enter_irqoff(). It should be the arch entry code
  * responsibility to call into context tracking with IRQs disabled.
  */
-void context_tracking_user_enter(void)
+void user_enter_callable(void)
 {
 	user_enter();
 }
-NOKPROBE_SYMBOL(context_tracking_user_enter);
+NOKPROBE_SYMBOL(user_enter_callable);
 
 /**
  * __ct_user_exit - Inform the context tracking that the CPU is
@@ -208,19 +211,22 @@ void context_tracking_exit(enum ctx_state state)
 NOKPROBE_SYMBOL(context_tracking_exit);
 EXPORT_SYMBOL_GPL(context_tracking_exit);
 
-/*
- * OBSOLETE:
- * This function should be noinstr but it unsafely calls local_irq_save(),
+/**
+ * user_exit_callable() - Unfortunate ASM callable version of user_exit() for
+ * 			  archs that didn't manage to check the context tracking
+ * 			  static key from low level code.
+ *
+ * This OBSOLETE function should be noinstr but it unsafely calls local_irq_save(),
  * involving illegal RCU uses through tracing and lockdep. This is unlikely
  * to be fixed as this function is obsolete. The preferred way is to call
  * user_exit_irqoff(). It should be the arch entry code responsibility to
  * call into context tracking with IRQs disabled.
  */
-void context_tracking_user_exit(void)
+void user_exit_callable(void)
 {
 	user_exit();
 }
-NOKPROBE_SYMBOL(context_tracking_user_exit);
+NOKPROBE_SYMBOL(user_exit_callable);
 
 void __init context_tracking_cpu_set(int cpu)
 {
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 07/23] context_tracking: Rename context_tracking_enter/exit() to ct_user_enter/exit()

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

context_tracking_enter() and context_tracking_exit() have confusing
names that don't explain the fact they are referring to user/guest state.

Use more self-explanatory names and shrink to the new context tracking
prefix instead.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking.h | 13 +++++++------
 kernel/context_tracking.c        | 12 ++++++------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 69532cd18f72c..7a5f04ae1758f 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -17,21 +17,22 @@ extern void context_tracking_cpu_set(int cpu);
 extern void __ct_user_enter(enum ctx_state state);
 extern void __ct_user_exit(enum ctx_state state);
 
-extern void context_tracking_enter(enum ctx_state state);
-extern void context_tracking_exit(enum ctx_state state);
+extern void ct_user_enter(enum ctx_state state);
+extern void ct_user_exit(enum ctx_state state);
+
 extern void user_enter_callable(void);
 extern void user_exit_callable(void);
 
 static inline void user_enter(void)
 {
 	if (context_tracking_enabled())
-		context_tracking_enter(CONTEXT_USER);
+		ct_user_enter(CONTEXT_USER);
 
 }
 static inline void user_exit(void)
 {
 	if (context_tracking_enabled())
-		context_tracking_exit(CONTEXT_USER);
+		ct_user_exit(CONTEXT_USER);
 }
 
 /* Called with interrupts disabled.  */
@@ -57,7 +58,7 @@ static inline enum ctx_state exception_enter(void)
 
 	prev_ctx = this_cpu_read(context_tracking.state);
 	if (prev_ctx != CONTEXT_KERNEL)
-		context_tracking_exit(prev_ctx);
+		ct_user_exit(prev_ctx);
 
 	return prev_ctx;
 }
@@ -67,7 +68,7 @@ static inline void exception_exit(enum ctx_state prev_ctx)
 	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) &&
 	    context_tracking_enabled()) {
 		if (prev_ctx != CONTEXT_KERNEL)
-			context_tracking_enter(prev_ctx);
+			ct_user_enter(prev_ctx);
 	}
 }
 
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 9d4a872ca92c4..87454e3515546 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -112,7 +112,7 @@ EXPORT_SYMBOL_GPL(__ct_user_enter);
  * or context_tracking_guest_enter(). It should be the arch entry code
  * responsibility to call into context tracking with IRQs disabled.
  */
-void context_tracking_enter(enum ctx_state state)
+void ct_user_enter(enum ctx_state state)
 {
 	unsigned long flags;
 
@@ -131,8 +131,8 @@ void context_tracking_enter(enum ctx_state state)
 	__ct_user_enter(state);
 	local_irq_restore(flags);
 }
-NOKPROBE_SYMBOL(context_tracking_enter);
-EXPORT_SYMBOL_GPL(context_tracking_enter);
+NOKPROBE_SYMBOL(ct_user_enter);
+EXPORT_SYMBOL_GPL(ct_user_enter);
 
 /**
  * user_enter_callable() - Unfortunate ASM callable version of user_enter() for
@@ -197,7 +197,7 @@ EXPORT_SYMBOL_GPL(__ct_user_exit);
  * or context_tracking_guest_exit(). It should be the arch entry code
  * responsibility to call into context tracking with IRQs disabled.
  */
-void context_tracking_exit(enum ctx_state state)
+void ct_user_exit(enum ctx_state state)
 {
 	unsigned long flags;
 
@@ -208,8 +208,8 @@ void context_tracking_exit(enum ctx_state state)
 	__ct_user_exit(state);
 	local_irq_restore(flags);
 }
-NOKPROBE_SYMBOL(context_tracking_exit);
-EXPORT_SYMBOL_GPL(context_tracking_exit);
+NOKPROBE_SYMBOL(ct_user_exit);
+EXPORT_SYMBOL_GPL(ct_user_exit);
 
 /**
  * user_exit_callable() - Unfortunate ASM callable version of user_exit() for
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 08/23] context_tracking: Rename context_tracking_cpu_set() to ct_cpu_track_user()

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

context_tracking_cpu_set() is called in order to tell a CPU to track
user/kernel transitions. Since context tracking is going to expand in
to also track transitions from/to idle/IRQ/NMIs, the scope
of this function name becomes too broad and needs to be made more
specific. Also shorten the prefix to align with the new namespace.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking.h | 2 +-
 kernel/context_tracking.c        | 4 ++--
 kernel/time/tick-sched.c         | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 7a5f04ae1758f..63259fece7c76 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -11,7 +11,7 @@
 
 
 #ifdef CONFIG_CONTEXT_TRACKING
-extern void context_tracking_cpu_set(int cpu);
+extern void ct_cpu_track_user(int cpu);
 
 /* Called with interrupts disabled.  */
 extern void __ct_user_enter(enum ctx_state state);
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 87454e3515546..7f457a1a1b551 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -228,7 +228,7 @@ void user_exit_callable(void)
 }
 NOKPROBE_SYMBOL(user_exit_callable);
 
-void __init context_tracking_cpu_set(int cpu)
+void __init ct_cpu_track_user(int cpu)
 {
 	static __initdata bool initialized = false;
 
@@ -258,6 +258,6 @@ void __init context_tracking_init(void)
 	int cpu;
 
 	for_each_possible_cpu(cpu)
-		context_tracking_cpu_set(cpu);
+		ct_cpu_track_user(cpu);
 }
 #endif
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 58a11f859ac79..de192dcff8282 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -571,7 +571,7 @@ void __init tick_nohz_init(void)
 	}
 
 	for_each_cpu(cpu, tick_nohz_full_mask)
-		context_tracking_cpu_set(cpu);
+		ct_cpu_track_user(cpu);
 
 	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 					"kernel/nohz:predown", NULL,
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 09/23] context_tracking: Split user tracking Kconfig

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Context tracking is going to be used not only to track user transitions
but also idle/IRQs/NMIs. The user tracking part will then become a
separate feature. Prepare Kconfig for that.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 .../time/context-tracking/arch-support.txt    |  6 ++--
 arch/Kconfig                                  |  4 +--
 arch/arm/Kconfig                              |  2 +-
 arch/arm/kernel/entry-common.S                |  4 +--
 arch/arm/kernel/entry-header.S                |  4 +--
 arch/arm64/Kconfig                            |  2 +-
 arch/csky/Kconfig                             |  2 +-
 arch/csky/kernel/entry.S                      |  4 +--
 arch/mips/Kconfig                             |  2 +-
 arch/powerpc/Kconfig                          |  2 +-
 arch/powerpc/include/asm/context_tracking.h   |  2 +-
 arch/riscv/Kconfig                            |  2 +-
 arch/riscv/kernel/entry.S                     |  6 ++--
 arch/sparc/Kconfig                            |  2 +-
 arch/sparc/kernel/rtrap_64.S                  |  2 +-
 arch/x86/Kconfig                              |  4 +--
 include/linux/context_tracking.h              | 12 +++----
 include/linux/context_tracking_state.h        |  4 +--
 init/Kconfig                                  |  4 +--
 kernel/context_tracking.c                     |  6 +++-
 kernel/sched/core.c                           |  2 +-
 kernel/time/Kconfig                           | 31 ++++++++++++-------
 22 files changed, 61 insertions(+), 48 deletions(-)

diff --git a/Documentation/features/time/context-tracking/arch-support.txt b/Documentation/features/time/context-tracking/arch-support.txt
index c9e0a16290e68..e59071a490901 100644
--- a/Documentation/features/time/context-tracking/arch-support.txt
+++ b/Documentation/features/time/context-tracking/arch-support.txt
@@ -1,7 +1,7 @@
 #
-# Feature name:          context-tracking
-#         Kconfig:       HAVE_CONTEXT_TRACKING
-#         description:   arch supports context tracking for NO_HZ_FULL
+# Feature name:          user-context-tracking
+#         Kconfig:       HAVE_CONTEXT_TRACKING_USER
+#         description:   arch supports user context tracking for NO_HZ_FULL
 #
     -----------------------
     |         arch |status|
diff --git a/arch/Kconfig b/arch/Kconfig
index fcf9a41a4ef5b..154b7b78da093 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -774,7 +774,7 @@ config HAVE_ARCH_WITHIN_STACK_FRAMES
 	  and similar) by implementing an inline arch_within_stack_frames(),
 	  which is used by CONFIG_HARDENED_USERCOPY.
 
-config HAVE_CONTEXT_TRACKING
+config HAVE_CONTEXT_TRACKING_USER
 	bool
 	help
 	  Provide kernel/user boundaries probes necessary for subsystems
@@ -785,7 +785,7 @@ config HAVE_CONTEXT_TRACKING
 	  protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
 	  handling on irq exit still need to be protected.
 
-config HAVE_CONTEXT_TRACKING_OFFSTACK
+config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
 	bool
 	help
 	  Architecture neither relies on exception_enter()/exception_exit()
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7630ba9cb6ccc..9acc6aac59126 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -84,7 +84,7 @@ config ARM
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE
 	select HAVE_ARM_SMCCC if CPU_V7
 	select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
-	select HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_BUILDTIME_MCOUNT_SORT
 	select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 7aa3ded4af929..37a0125fc9265 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -28,7 +28,7 @@
 #include "entry-header.S"
 
 saved_psr	.req	r8
-#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
+#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER)
 saved_pc	.req	r9
 #define TRACE(x...) x
 #else
@@ -38,7 +38,7 @@ saved_pc	.req	lr
 
 	.section .entry.text,"ax",%progbits
 	.align	5
-#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \
+#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING_USER) || \
 	IS_ENABLED(CONFIG_DEBUG_RSEQ))
 /*
  * This is the fast syscall return path.  We do as little as possible here,
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 95def2b38d1ca..99411fa913501 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -366,7 +366,7 @@ ALT_UP_B(.L1_\@)
  * between user and kernel mode.
  */
 	.macro ct_user_exit, save = 1
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	.if	\save
 	stmdb   sp!, {r0-r3, ip, lr}
 	bl	user_exit_callable
@@ -378,7 +378,7 @@ ALT_UP_B(.L1_\@)
 	.endm
 
 	.macro ct_user_enter, save = 1
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	.if	\save
 	stmdb   sp!, {r0-r3, ip, lr}
 	bl	user_enter_callable
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1652a9800ebee..7c5dd2af9ca95 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -174,7 +174,7 @@ config ARM64
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL
-	select HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 21d72b078eefc..f55ba1745f7b9 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -42,7 +42,7 @@ config CSKY
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_SECCOMP_FILTER
-	select HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_DEBUG_KMEMLEAK
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
index bc734d17c16f4..547b4cd1b24b4 100644
--- a/arch/csky/kernel/entry.S
+++ b/arch/csky/kernel/entry.S
@@ -19,7 +19,7 @@
 .endm
 
 .macro	context_tracking
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	mfcr	a0, epsr
 	btsti	a0, 31
 	bt	1f
@@ -159,7 +159,7 @@ ret_from_exception:
 	and	r10, r9
 	cmpnei	r10, 0
 	bt	exit_work
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	jbsr	user_enter_callable
 #endif
 1:
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index db09d45d59ec7..9457894db2375 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -56,7 +56,7 @@ config MIPS
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES
 	select HAVE_ASM_MODVERSIONS
-	select HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_TIF_NOHZ
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c2ce2e60c8f0f..874c8d81284ad 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -202,7 +202,7 @@ config PPC
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ASM_MODVERSIONS
-	select HAVE_CONTEXT_TRACKING		if PPC64
+	select HAVE_CONTEXT_TRACKING_USER		if PPC64
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DEBUG_STACKOVERFLOW
diff --git a/arch/powerpc/include/asm/context_tracking.h b/arch/powerpc/include/asm/context_tracking.h
index f2682b28b0502..4b63931c49e0e 100644
--- a/arch/powerpc/include/asm/context_tracking.h
+++ b/arch/powerpc/include/asm/context_tracking.h
@@ -2,7 +2,7 @@
 #ifndef _ASM_POWERPC_CONTEXT_TRACKING_H
 #define _ASM_POWERPC_CONTEXT_TRACKING_H
 
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 #define SCHEDULE_USER bl	schedule_user
 #else
 #define SCHEDULE_USER bl	schedule
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 32ffef9f6e5b4..29b46f2173457 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -86,7 +86,7 @@ config RISCV
 	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_VMAP_STACK if MMU && 64BIT
 	select HAVE_ASM_MODVERSIONS
-	select HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_EBPF_JIT if MMU
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 12f6bba57e335..b9eda3fcbd6d7 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -111,7 +111,7 @@ _save_context:
 	call __trace_hardirqs_off
 #endif
 
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	/* If previous state is in user mode, call user_exit_callable(). */
 	li   a0, SR_PP
 	and a0, s1, a0
@@ -176,7 +176,7 @@ handle_syscall:
 	 */
 	csrs CSR_STATUS, SR_IE
 #endif
-#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING)
+#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER)
 	/* Recover a0 - a7 for system calls */
 	REG_L a0, PT_A0(sp)
 	REG_L a1, PT_A1(sp)
@@ -269,7 +269,7 @@ resume_userspace:
 	andi s1, s0, _TIF_WORK_MASK
 	bnez s1, work_pending
 
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	call user_enter_callable
 #endif
 
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index ba449c47effd8..9232411a8821a 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -71,7 +71,7 @@ config SPARC64
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_SYSCALL_TRACEPOINTS
-	select HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER
 	select HAVE_TIF_NOHZ
 	select HAVE_DEBUG_KMEMLEAK
 	select IOMMU_HELPER
diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S
index c5fd4b450d9b6..eef102765a7e2 100644
--- a/arch/sparc/kernel/rtrap_64.S
+++ b/arch/sparc/kernel/rtrap_64.S
@@ -15,7 +15,7 @@
 #include <asm/visasm.h>
 #include <asm/processor.h>
 
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 # define SCHEDULE_USER schedule_user
 #else
 # define SCHEDULE_USER schedule
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index be0b95e51df66..b0a6dbbb760bc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -186,8 +186,8 @@ config X86
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL
-	select HAVE_CONTEXT_TRACKING		if X86_64
-	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
+	select HAVE_CONTEXT_TRACKING_USER		if X86_64
+	select HAVE_CONTEXT_TRACKING_USER_OFFSTACK	if HAVE_CONTEXT_TRACKING_USER
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_OBJTOOL_MCOUNT		if HAVE_OBJTOOL
 	select HAVE_BUILDTIME_MCOUNT_SORT
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 63259fece7c76..e35ae66b4794e 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -10,7 +10,7 @@
 #include <asm/ptrace.h>
 
 
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 extern void ct_cpu_track_user(int cpu);
 
 /* Called with interrupts disabled.  */
@@ -52,7 +52,7 @@ static inline enum ctx_state exception_enter(void)
 {
 	enum ctx_state prev_ctx;
 
-	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) ||
+	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) ||
 	    !context_tracking_enabled())
 		return 0;
 
@@ -65,7 +65,7 @@ static inline enum ctx_state exception_enter(void)
 
 static inline void exception_exit(enum ctx_state prev_ctx)
 {
-	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) &&
+	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) &&
 	    context_tracking_enabled()) {
 		if (prev_ctx != CONTEXT_KERNEL)
 			ct_user_enter(prev_ctx);
@@ -109,14 +109,14 @@ static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
 static __always_inline bool context_tracking_guest_enter(void) { return false; }
 static inline void context_tracking_guest_exit(void) { }
 
-#endif /* !CONFIG_CONTEXT_TRACKING */
+#endif /* !CONFIG_CONTEXT_TRACKING_USER */
 
 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
 
-#ifdef CONFIG_CONTEXT_TRACKING_FORCE
+#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE
 extern void context_tracking_init(void);
 #else
 static inline void context_tracking_init(void) { }
-#endif /* CONFIG_CONTEXT_TRACKING_FORCE */
+#endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */
 
 #endif
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index edc7b46376a6b..2b46afe105a96 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -22,7 +22,7 @@ struct context_tracking {
 	} state;
 };
 
-#ifdef CONFIG_CONTEXT_TRACKING
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 extern struct static_key_false context_tracking_key;
 DECLARE_PER_CPU(struct context_tracking, context_tracking);
 
@@ -45,6 +45,6 @@ static inline bool context_tracking_enabled_this_cpu(void)
 static __always_inline bool context_tracking_enabled(void) { return false; }
 static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
 static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; }
-#endif /* CONFIG_CONTEXT_TRACKING */
+#endif /* CONFIG_CONTEXT_TRACKING_USER */
 
 #endif
diff --git a/init/Kconfig b/init/Kconfig
index c7900e8975f18..06454d19e2f0a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -494,11 +494,11 @@ config VIRT_CPU_ACCOUNTING_NATIVE
 
 config VIRT_CPU_ACCOUNTING_GEN
 	bool "Full dynticks CPU time accounting"
-	depends on HAVE_CONTEXT_TRACKING
+	depends on HAVE_CONTEXT_TRACKING_USER
 	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	depends on GENERIC_CLOCKEVENTS
 	select VIRT_CPU_ACCOUNTING
-	select CONTEXT_TRACKING
+	select CONTEXT_TRACKING_USER
 	help
 	  Select this option to enable task and CPU time accounting on full
 	  dynticks systems. This accounting is implemented by watching every
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 7f457a1a1b551..a6997daf27d10 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -22,6 +22,8 @@
 #include <linux/export.h>
 #include <linux/kprobes.h>
 
+#ifdef CONFIG_CONTEXT_TRACKING_USER
+
 #define CREATE_TRACE_POINTS
 #include <trace/events/context_tracking.h>
 
@@ -252,7 +254,7 @@ void __init ct_cpu_track_user(int cpu)
 	initialized = true;
 }
 
-#ifdef CONFIG_CONTEXT_TRACKING_FORCE
+#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE
 void __init context_tracking_init(void)
 {
 	int cpu;
@@ -261,3 +263,5 @@ void __init context_tracking_init(void)
 		ct_cpu_track_user(cpu);
 }
 #endif
+
+#endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index da0bf6fe9ecdc..883167a57bf9d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6559,7 +6559,7 @@ void __sched schedule_idle(void)
 	} while (need_resched());
 }
 
-#if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK)
+#if defined(CONFIG_CONTEXT_TRACKING_USER) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK)
 asmlinkage __visible void __sched schedule_user(void)
 {
 	/*
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 27b7868b5c30d..41f99bcfe9e66 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -73,6 +73,9 @@ config TIME_KUNIT_TEST
 
 	  If unsure, say N.
 
+config CONTEXT_TRACKING
+	bool
+
 if GENERIC_CLOCKEVENTS
 menu "Timers subsystem"
 
@@ -111,7 +114,7 @@ config NO_HZ_FULL
 	# NO_HZ_COMMON dependency
 	# We need at least one periodic CPU for timekeeping
 	depends on SMP
-	depends on HAVE_CONTEXT_TRACKING
+	depends on HAVE_CONTEXT_TRACKING_USER
 	# VIRT_CPU_ACCOUNTING_GEN dependency
 	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select NO_HZ_COMMON
@@ -137,31 +140,37 @@ config NO_HZ_FULL
 
 endchoice
 
-config CONTEXT_TRACKING
-       bool
+config CONTEXT_TRACKING_USER
+	bool
+	depends on HAVE_CONTEXT_TRACKING_USER
+	select CONTEXT_TRACKING
+	help
+	  Track transitions between kernel and user on behalf of RCU and
+	  tickless cputime accounting. The former case relies on context
+	  tracking to enter/exit RCU extended quiescent states.
 
-config CONTEXT_TRACKING_FORCE
-	bool "Force context tracking"
-	depends on CONTEXT_TRACKING
+config CONTEXT_TRACKING_USER_FORCE
+	bool "Force user context tracking"
+	depends on CONTEXT_TRACKING_USER
 	default y if !NO_HZ_FULL
 	help
 	  The major pre-requirement for full dynticks to work is to
-	  support the context tracking subsystem. But there are also
+	  support the user context tracking subsystem. But there are also
 	  other dependencies to provide in order to make the full
 	  dynticks working.
 
 	  This option stands for testing when an arch implements the
-	  context tracking backend but doesn't yet fulfill all the
+	  user context tracking backend but doesn't yet fulfill all the
 	  requirements to make the full dynticks feature working.
 	  Without the full dynticks, there is no way to test the support
-	  for context tracking and the subsystems that rely on it: RCU
+	  for user context tracking and the subsystems that rely on it: RCU
 	  userspace extended quiescent state and tickless cputime
 	  accounting. This option copes with the absence of the full
-	  dynticks subsystem by forcing the context tracking on all
+	  dynticks subsystem by forcing the user context tracking on all
 	  CPUs in the system.
 
 	  Say Y only if you're working on the development of an
-	  architecture backend for the context tracking.
+	  architecture backend for the user context tracking.
 
 	  Say N otherwise, this option brings an overhead that you
 	  don't want in production.
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 10/23] context_tracking: Take idle eqs entrypoints over RCU

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

The RCU dynticks counter is going to be merged into the context tracking
subsystem. Start with moving the idle extended quiescent states
entrypoints to context tracking. For now those are dumb redirections to
existing RCU calls.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 Documentation/RCU/stallwarn.rst   |  4 ++--
 arch/arm/mach-imx/cpuidle-imx6q.c |  5 +++--
 drivers/acpi/processor_idle.c     |  5 +++--
 drivers/cpuidle/cpuidle.c         |  9 +++++----
 include/linux/context_tracking.h  |  8 ++++++++
 include/linux/rcupdate.h          |  2 +-
 kernel/context_tracking.c         | 15 +++++++++++++++
 kernel/locking/lockdep.c          |  2 +-
 kernel/rcu/Kconfig                |  2 ++
 kernel/rcu/tree.c                 |  2 --
 kernel/rcu/update.c               |  2 +-
 kernel/sched/idle.c               | 10 +++++-----
 kernel/sched/sched.h              |  1 +
 kernel/time/Kconfig               |  6 ++++++
 14 files changed, 53 insertions(+), 20 deletions(-)

diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst
index 794837eb519b9..b95bda7755fa9 100644
--- a/Documentation/RCU/stallwarn.rst
+++ b/Documentation/RCU/stallwarn.rst
@@ -97,8 +97,8 @@ warnings:
 	which will include additional debugging information.
 
 -	A low-level kernel issue that either fails to invoke one of the
-	variants of rcu_user_enter(), rcu_user_exit(), rcu_idle_enter(),
-	rcu_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one
+	variants of rcu_user_enter(), rcu_user_exit(), ct_idle_enter(),
+	ct_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one
 	hand, or that invokes one of them too many times on the other.
 	Historically, the most frequent issue has been an omission
 	of either irq_enter() or irq_exit(), which in turn invoke
diff --git a/arch/arm/mach-imx/cpuidle-imx6q.c b/arch/arm/mach-imx/cpuidle-imx6q.c
index 094337dc1bc7e..d086cbae09c37 100644
--- a/arch/arm/mach-imx/cpuidle-imx6q.c
+++ b/arch/arm/mach-imx/cpuidle-imx6q.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2012 Freescale Semiconductor, Inc.
  */
 
+#include <linux/context_tracking.h>
 #include <linux/cpuidle.h>
 #include <linux/module.h>
 #include <asm/cpuidle.h>
@@ -24,9 +25,9 @@ static int imx6q_enter_wait(struct cpuidle_device *dev,
 		imx6_set_lpm(WAIT_UNCLOCKED);
 	raw_spin_unlock(&cpuidle_lock);
 
-	rcu_idle_enter();
+	ct_idle_enter();
 	cpu_do_idle();
-	rcu_idle_exit();
+	ct_idle_exit();
 
 	raw_spin_lock(&cpuidle_lock);
 	if (num_idle_cpus-- == num_online_cpus())
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 6a5572a1a80cc..1401d193a2dfc 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -23,6 +23,7 @@
 #include <linux/minmax.h>
 #include <linux/perf_event.h>
 #include <acpi/processor.h>
+#include <linux/context_tracking.h>
 
 /*
  * Include the apic definitions for x86 to have the APIC timer related defines
@@ -647,11 +648,11 @@ static int acpi_idle_enter_bm(struct cpuidle_driver *drv,
 		raw_spin_unlock(&c3_lock);
 	}
 
-	rcu_idle_enter();
+	ct_idle_enter();
 
 	acpi_idle_do_entry(cx);
 
-	rcu_idle_exit();
+	ct_idle_exit();
 
 	/* Re-enable bus master arbitration */
 	if (dis_bm) {
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index ef2ea1b12cd84..62dd956025f33 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -23,6 +23,7 @@
 #include <linux/suspend.h>
 #include <linux/tick.h>
 #include <linux/mmu_context.h>
+#include <linux/context_tracking.h>
 #include <trace/events/power.h>
 
 #include "cpuidle.h"
@@ -150,12 +151,12 @@ static void enter_s2idle_proper(struct cpuidle_driver *drv,
 	 */
 	stop_critical_timings();
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		rcu_idle_enter();
+		ct_idle_enter();
 	target_state->enter_s2idle(dev, drv, index);
 	if (WARN_ON_ONCE(!irqs_disabled()))
 		local_irq_disable();
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		rcu_idle_exit();
+		ct_idle_exit();
 	tick_unfreeze();
 	start_critical_timings();
 
@@ -233,10 +234,10 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 
 	stop_critical_timings();
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		rcu_idle_enter();
+		ct_idle_enter();
 	entered_state = target_state->enter(dev, drv, index);
 	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
-		rcu_idle_exit();
+		ct_idle_exit();
 	start_critical_timings();
 
 	sched_clock_idle_wakeup_event();
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index e35ae66b4794e..01abadb2f9930 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -119,4 +119,12 @@ extern void context_tracking_init(void);
 static inline void context_tracking_init(void) { }
 #endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */
 
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+extern void ct_idle_enter(void);
+extern void ct_idle_exit(void);
+#else
+static inline void ct_idle_enter(void) { }
+static inline void ct_idle_exit(void) { }
+#endif /* !CONFIG_CONTEXT_TRACKING_IDLE */
+
 #endif
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 1a32036c918cd..6ebe754501c38 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -128,7 +128,7 @@ static inline void rcu_nocb_flush_deferred_wakeup(void) { }
  * @a: Code that RCU needs to pay attention to.
  *
  * RCU read-side critical sections are forbidden in the inner idle loop,
- * that is, between the rcu_idle_enter() and the rcu_idle_exit() -- RCU
+ * that is, between the ct_idle_enter() and the ct_idle_exit() -- RCU
  * will happily ignore any such read-side critical sections.  However,
  * things like powertop need tracepoints in the inner idle loop.
  *
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index a6997daf27d10..e9904f935f7f4 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -22,6 +22,21 @@
 #include <linux/export.h>
 #include <linux/kprobes.h>
 
+
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+noinstr void ct_idle_enter(void)
+{
+	rcu_idle_enter();
+}
+EXPORT_SYMBOL_GPL(ct_idle_enter);
+
+void ct_idle_exit(void)
+{
+	rcu_idle_exit();
+}
+EXPORT_SYMBOL_GPL(ct_idle_exit);
+#endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
+
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 
 #define CREATE_TRACE_POINTS
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index f06b91ca6482d..5ea690cb4f7af 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -6570,7 +6570,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 
 	/*
 	 * If a CPU is in the RCU-free window in idle (ie: in the section
-	 * between rcu_idle_enter() and rcu_idle_exit(), then RCU
+	 * between ct_idle_enter() and ct_idle_exit(), then RCU
 	 * considers that CPU to be in an "extended quiescent state",
 	 * which means that RCU will be completely ignoring that CPU.
 	 * Therefore, rcu_read_lock() and friends have absolutely no
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 1c630e573548d..3fa24e63d6f9b 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -8,6 +8,8 @@ menu "RCU Subsystem"
 config TREE_RCU
 	bool
 	default y if SMP
+	# Dynticks-idle tracking
+	select CONTEXT_TRACKING_IDLE
 	help
 	  This option selects the RCU implementation that is
 	  designed for very large SMP system with hundreds or
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 9a5edab5558c9..051fed0844b67 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -664,7 +664,6 @@ void noinstr rcu_idle_enter(void)
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
 	rcu_eqs_enter(false);
 }
-EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
 #ifdef CONFIG_NO_HZ_FULL
 
@@ -904,7 +903,6 @@ void noinstr rcu_idle_exit(void)
 	rcu_eqs_exit(false);
 	raw_local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(rcu_idle_exit);
 
 #ifdef CONFIG_NO_HZ_FULL
 /**
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index fc7fef5756064..147214b2cd68e 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -85,7 +85,7 @@ module_param(rcu_normal_after_boot, int, 0444);
  * and while lockdep is disabled.
  *
  * Note that if the CPU is in the idle loop from an RCU point of view (ie:
- * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
+ * that we are in the section between ct_idle_enter() and ct_idle_exit())
  * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an
  * rcu_read_lock().  The reason for this is that RCU ignores CPUs that are
  * in such a section, considering these as in extended quiescent state,
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 328cccbee4441..f26ab2675f7d7 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -53,14 +53,14 @@ static noinline int __cpuidle cpu_idle_poll(void)
 {
 	trace_cpu_idle(0, smp_processor_id());
 	stop_critical_timings();
-	rcu_idle_enter();
+	ct_idle_enter();
 	local_irq_enable();
 
 	while (!tif_need_resched() &&
 	       (cpu_idle_force_poll || tick_check_broadcast_expired()))
 		cpu_relax();
 
-	rcu_idle_exit();
+	ct_idle_exit();
 	start_critical_timings();
 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 
@@ -98,12 +98,12 @@ void __cpuidle default_idle_call(void)
 		 *
 		 * Trace IRQs enable here, then switch off RCU, and have
 		 * arch_cpu_idle() use raw_local_irq_enable(). Note that
-		 * rcu_idle_enter() relies on lockdep IRQ state, so switch that
+		 * ct_idle_enter() relies on lockdep IRQ state, so switch that
 		 * last -- this is very similar to the entry code.
 		 */
 		trace_hardirqs_on_prepare();
 		lockdep_hardirqs_on_prepare();
-		rcu_idle_enter();
+		ct_idle_enter();
 		lockdep_hardirqs_on(_THIS_IP_);
 
 		arch_cpu_idle();
@@ -116,7 +116,7 @@ void __cpuidle default_idle_call(void)
 		 */
 		raw_local_irq_disable();
 		lockdep_hardirqs_off(_THIS_IP_);
-		rcu_idle_exit();
+		ct_idle_exit();
 		lockdep_hardirqs_on(_THIS_IP_);
 		raw_local_irq_enable();
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 47b89a0fc6e55..0cfe2d0af2947 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -27,6 +27,7 @@
 #include <linux/capability.h>
 #include <linux/cgroup_api.h>
 #include <linux/cgroup.h>
+#include <linux/context_tracking.h>
 #include <linux/cpufreq.h>
 #include <linux/cpumask_api.h>
 #include <linux/ctype.h>
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 41f99bcfe9e66..a41753be1a2bf 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -76,6 +76,12 @@ config TIME_KUNIT_TEST
 config CONTEXT_TRACKING
 	bool
 
+config CONTEXT_TRACKING_IDLE
+	bool
+	select CONTEXT_TRACKING
+	help
+	  Tracks idle state on behalf of RCU.
+
 if GENERIC_CLOCKEVENTS
 menu "Timers subsystem"
 
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 11/23] context_tracking: Take IRQ eqs entrypoints over RCU

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

The RCU dynticks counter is going to be merged into the context tracking
subsystem. Prepare with moving the IRQ extended quiescent states
entrypoints to context tracking. For now those are dumb redirection to
existing RCU calls.

[ paulmck: Apply Stephen Rothwell feedback from -next. ]
[ paulmck: Apply Nathan Chancellor feedback. ]

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 .../RCU/Design/Requirements/Requirements.rst  | 10 ++++----
 Documentation/RCU/stallwarn.rst               |  4 ++--
 arch/Kconfig                                  |  2 +-
 arch/arm64/kernel/entry-common.c              |  6 ++---
 arch/x86/mm/fault.c                           |  2 +-
 drivers/cpuidle/cpuidle-psci.c                |  8 +++----
 drivers/cpuidle/cpuidle-riscv-sbi.c           |  8 +++----
 include/linux/context_tracking_irq.h          | 17 +++++++++++++
 include/linux/context_tracking_state.h        |  1 +
 include/linux/entry-common.h                  | 10 ++++----
 include/linux/rcupdate.h                      |  5 ++--
 include/linux/tracepoint.h                    |  4 ++--
 kernel/cfi.c                                  |  4 ++--
 kernel/context_tracking.c                     | 24 +++++++++++++++++--
 kernel/cpu_pm.c                               |  8 +++----
 kernel/entry/common.c                         | 12 +++++-----
 kernel/softirq.c                              |  4 ++--
 kernel/trace/trace.c                          |  6 ++---
 18 files changed, 87 insertions(+), 48 deletions(-)
 create mode 100644 include/linux/context_tracking_irq.h

diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
index 04ed8bf27a0ea..074810c739367 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.rst
+++ b/Documentation/RCU/Design/Requirements/Requirements.rst
@@ -1844,10 +1844,10 @@ that meets this requirement.
 
 Furthermore, NMI handlers can be interrupted by what appear to RCU to be
 normal interrupts. One way that this can happen is for code that
-directly invokes rcu_irq_enter() and rcu_irq_exit() to be called
+directly invokes ct_irq_enter() and ct_irq_exit() to be called
 from an NMI handler. This astonishing fact of life prompted the current
-code structure, which has rcu_irq_enter() invoking
-rcu_nmi_enter() and rcu_irq_exit() invoking rcu_nmi_exit().
+code structure, which has ct_irq_enter() invoking
+rcu_nmi_enter() and ct_irq_exit() invoking rcu_nmi_exit().
 And yes, I also learned of this requirement the hard way.
 
 Loadable Modules
@@ -2195,7 +2195,7 @@ scheduling-clock interrupt be enabled when RCU needs it to be:
    sections, and RCU believes this CPU to be idle, no problem. This
    sort of thing is used by some architectures for light-weight
    exception handlers, which can then avoid the overhead of
-   rcu_irq_enter() and rcu_irq_exit() at exception entry and
+   ct_irq_enter() and ct_irq_exit() at exception entry and
    exit, respectively. Some go further and avoid the entireties of
    irq_enter() and irq_exit().
    Just make very sure you are running some of your tests with
@@ -2226,7 +2226,7 @@ scheduling-clock interrupt be enabled when RCU needs it to be:
 +-----------------------------------------------------------------------+
 | **Answer**:                                                           |
 +-----------------------------------------------------------------------+
-| One approach is to do ``rcu_irq_exit();rcu_irq_enter();`` every so    |
+| One approach is to do ``ct_irq_exit();ct_irq_enter();`` every so      |
 | often. But given that long-running interrupt handlers can cause other |
 | problems, not least for response time, shouldn't you work to keep     |
 | your interrupt handler's runtime within reasonable bounds?            |
diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst
index b95bda7755fa9..ce1f58a9d954b 100644
--- a/Documentation/RCU/stallwarn.rst
+++ b/Documentation/RCU/stallwarn.rst
@@ -98,11 +98,11 @@ warnings:
 
 -	A low-level kernel issue that either fails to invoke one of the
 	variants of rcu_user_enter(), rcu_user_exit(), ct_idle_enter(),
-	ct_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one
+	ct_idle_exit(), ct_irq_enter(), or ct_irq_exit() on the one
 	hand, or that invokes one of them too many times on the other.
 	Historically, the most frequent issue has been an omission
 	of either irq_enter() or irq_exit(), which in turn invoke
-	rcu_irq_enter() or rcu_irq_exit(), respectively.  Building your
+	ct_irq_enter() or ct_irq_exit(), respectively.  Building your
 	kernel with CONFIG_RCU_EQS_DEBUG=y can help track down these types
 	of issues, which sometimes arise in architecture-specific code.
 
diff --git a/arch/Kconfig b/arch/Kconfig
index 154b7b78da093..342642be105fc 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -782,7 +782,7 @@ config HAVE_CONTEXT_TRACKING_USER
 	  Syscalls need to be wrapped inside user_exit()-user_enter(), either
 	  optimized behind static key or through the slow path using TIF_NOHZ
 	  flag. Exceptions handlers must be wrapped as well. Irqs are already
-	  protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
+	  protected inside ct_irq_enter/ct_irq_exit() but preemption or signal
 	  handling on irq exit still need to be protected.
 
 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 56cefd33eb8e9..8dabe9ec10f16 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -41,7 +41,7 @@ static __always_inline void __enter_from_kernel_mode(struct pt_regs *regs)
 
 	if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
 		lockdep_hardirqs_off(CALLER_ADDR0);
-		rcu_irq_enter();
+		ct_irq_enter();
 		trace_hardirqs_off_finish();
 
 		regs->exit_rcu = true;
@@ -76,7 +76,7 @@ static __always_inline void __exit_to_kernel_mode(struct pt_regs *regs)
 		if (regs->exit_rcu) {
 			trace_hardirqs_on_prepare();
 			lockdep_hardirqs_on_prepare();
-			rcu_irq_exit();
+			ct_irq_exit();
 			lockdep_hardirqs_on(CALLER_ADDR0);
 			return;
 		}
@@ -84,7 +84,7 @@ static __always_inline void __exit_to_kernel_mode(struct pt_regs *regs)
 		trace_hardirqs_on();
 	} else {
 		if (regs->exit_rcu)
-			rcu_irq_exit();
+			ct_irq_exit();
 	}
 }
 
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fad8faa29d042..971977c438fc1 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1526,7 +1526,7 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault)
 
 	/*
 	 * Entry handling for valid #PF from kernel mode is slightly
-	 * different: RCU is already watching and rcu_irq_enter() must not
+	 * different: RCU is already watching and ct_irq_enter() must not
 	 * be invoked because a kernel fault on a user space address might
 	 * sleep.
 	 *
diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index 540105ca0781f..57bc3e3ae3912 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -69,12 +69,12 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 		return -1;
 
 	/* Do runtime PM to manage a hierarchical CPU toplogy. */
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	if (s2idle)
 		dev_pm_genpd_suspend(pd_dev);
 	else
 		pm_runtime_put_sync_suspend(pd_dev);
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 
 	state = psci_get_domain_state();
 	if (!state)
@@ -82,12 +82,12 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
 
 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;
 
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	if (s2idle)
 		dev_pm_genpd_resume(pd_dev);
 	else
 		pm_runtime_get_sync(pd_dev);
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 
 	cpu_pm_exit();
 
diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
index 1151e5e2ba824..862a2876f1c9d 100644
--- a/drivers/cpuidle/cpuidle-riscv-sbi.c
+++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
@@ -116,12 +116,12 @@ static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
 		return -1;
 
 	/* Do runtime PM to manage a hierarchical CPU toplogy. */
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	if (s2idle)
 		dev_pm_genpd_suspend(pd_dev);
 	else
 		pm_runtime_put_sync_suspend(pd_dev);
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 
 	if (sbi_is_domain_state_available())
 		state = sbi_get_domain_state();
@@ -130,12 +130,12 @@ static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
 
 	ret = sbi_suspend(state) ? -1 : idx;
 
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	if (s2idle)
 		dev_pm_genpd_resume(pd_dev);
 	else
 		pm_runtime_get_sync(pd_dev);
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 
 	cpu_pm_exit();
 
diff --git a/include/linux/context_tracking_irq.h b/include/linux/context_tracking_irq.h
new file mode 100644
index 0000000000000..62f62bbd1a50d
--- /dev/null
+++ b/include/linux/context_tracking_irq.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CONTEXT_TRACKING_IRQ_H
+#define _LINUX_CONTEXT_TRACKING_IRQ_H
+
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+void ct_irq_enter(void);
+void ct_irq_exit(void);
+void ct_irq_enter_irqson(void);
+void ct_irq_exit_irqson(void);
+#else
+static inline void ct_irq_enter(void) { }
+static inline void ct_irq_exit(void) { }
+static inline void ct_irq_enter_irqson(void) { }
+static inline void ct_irq_exit_irqson(void) { }
+#endif
+
+#endif
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 2b46afe105a96..9c16a8b2c1947 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -4,6 +4,7 @@
 
 #include <linux/percpu.h>
 #include <linux/static_key.h>
+#include <linux/context_tracking_irq.h>
 
 struct context_tracking {
 	/*
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index c92ac75d6556d..84a466b176cf4 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -357,7 +357,7 @@ void irqentry_exit_to_user_mode(struct pt_regs *regs);
 /**
  * struct irqentry_state - Opaque object for exception state storage
  * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the
- *            exit path has to invoke rcu_irq_exit().
+ *            exit path has to invoke ct_irq_exit().
  * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that
  *           lockdep state is restored correctly on exit from nmi.
  *
@@ -395,12 +395,12 @@ typedef struct irqentry_state {
  *
  * For kernel mode entries RCU handling is done conditional. If RCU is
  * watching then the only RCU requirement is to check whether the tick has
- * to be restarted. If RCU is not watching then rcu_irq_enter() has to be
- * invoked on entry and rcu_irq_exit() on exit.
+ * to be restarted. If RCU is not watching then ct_irq_enter() has to be
+ * invoked on entry and ct_irq_exit() on exit.
  *
- * Avoiding the rcu_irq_enter/exit() calls is an optimization but also
+ * Avoiding the ct_irq_enter/exit() calls is an optimization but also
  * solves the problem of kernel mode pagefaults which can schedule, which
- * is not possible after invoking rcu_irq_enter() without undoing it.
+ * is not possible after invoking ct_irq_enter() without undoing it.
  *
  * For user mode entries irqentry_enter_from_user_mode() is invoked to
  * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 6ebe754501c38..f1562d91c67d2 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -29,6 +29,7 @@
 #include <linux/lockdep.h>
 #include <asm/processor.h>
 #include <linux/cpumask.h>
+#include <linux/context_tracking_irq.h>
 
 #define ULONG_CMP_GE(a, b)	(ULONG_MAX / 2 >= (a) - (b))
 #define ULONG_CMP_LT(a, b)	(ULONG_MAX / 2 < (a) - (b))
@@ -143,9 +144,9 @@ static inline void rcu_nocb_flush_deferred_wakeup(void) { }
  */
 #define RCU_NONIDLE(a) \
 	do { \
-		rcu_irq_enter_irqson(); \
+		ct_irq_enter_irqson(); \
 		do { a; } while (0); \
-		rcu_irq_exit_irqson(); \
+		ct_irq_exit_irqson(); \
 	} while (0)
 
 /*
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 28031b15f8783..55717a2eda08a 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -200,13 +200,13 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 		 */							\
 		if (rcuidle) {						\
 			__idx = srcu_read_lock_notrace(&tracepoint_srcu);\
-			rcu_irq_enter_irqson();				\
+			ct_irq_enter_irqson();				\
 		}							\
 									\
 		__DO_TRACE_CALL(name, TP_ARGS(args));			\
 									\
 		if (rcuidle) {						\
-			rcu_irq_exit_irqson();				\
+			ct_irq_exit_irqson();				\
 			srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
 		}							\
 									\
diff --git a/kernel/cfi.c b/kernel/cfi.c
index 08102d19ec15a..2046276ee2348 100644
--- a/kernel/cfi.c
+++ b/kernel/cfi.c
@@ -295,7 +295,7 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr)
 	rcu_idle = !rcu_is_watching();
 	if (rcu_idle) {
 		local_irq_save(flags);
-		rcu_irq_enter();
+		ct_irq_enter();
 	}
 
 	if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW))
@@ -304,7 +304,7 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr)
 		fn = find_module_check_fn(ptr);
 
 	if (rcu_idle) {
-		rcu_irq_exit();
+		ct_irq_exit();
 		local_irq_restore(flags);
 	}
 
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index e9904f935f7f4..891464f7aa5a4 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -35,6 +35,26 @@ void ct_idle_exit(void)
 	rcu_idle_exit();
 }
 EXPORT_SYMBOL_GPL(ct_idle_exit);
+
+noinstr void ct_irq_enter(void)
+{
+	rcu_irq_enter();
+}
+
+noinstr void ct_irq_exit(void)
+{
+	rcu_irq_exit();
+}
+
+void ct_irq_enter_irqson(void)
+{
+	rcu_irq_enter_irqson();
+}
+
+void ct_irq_exit_irqson(void)
+{
+	rcu_irq_exit_irqson();
+}
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
 #ifdef CONFIG_CONTEXT_TRACKING_USER
@@ -90,7 +110,7 @@ void noinstr __ct_user_enter(enum ctx_state state)
 			 * At this stage, only low level arch entry code remains and
 			 * then we'll run in userspace. We can assume there won't be
 			 * any RCU read-side critical section until the next call to
-			 * user_exit() or rcu_irq_enter(). Let's remove RCU's dependency
+			 * user_exit() or ct_irq_enter(). Let's remove RCU's dependency
 			 * on the tick.
 			 */
 			if (state == CONTEXT_USER) {
@@ -136,7 +156,7 @@ void ct_user_enter(enum ctx_state state)
 	/*
 	 * Some contexts may involve an exception occuring in an irq,
 	 * leading to that nesting:
-	 * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit()
+	 * ct_irq_enter() rcu_user_exit() rcu_user_exit() ct_irq_exit()
 	 * This would mess up the dyntick_nesting count though. And rcu_irq_*()
 	 * helpers are enough to protect RCU uses inside the exception. So
 	 * just return immediately if we detect we are in an IRQ.
diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c
index 246efc74e3f34..ba4ba71facf97 100644
--- a/kernel/cpu_pm.c
+++ b/kernel/cpu_pm.c
@@ -35,11 +35,11 @@ static int cpu_pm_notify(enum cpu_pm_event event)
 	 * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
 	 * this.
 	 */
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	rcu_read_lock();
 	ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
 	rcu_read_unlock();
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 
 	return notifier_to_errno(ret);
 }
@@ -49,11 +49,11 @@ static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event ev
 	unsigned long flags;
 	int ret;
 
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
 	ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
 	raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 
 	return notifier_to_errno(ret);
 }
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 032f164abe7ce..667ba5d581ff7 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -321,7 +321,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 	}
 
 	/*
-	 * If this entry hit the idle task invoke rcu_irq_enter() whether
+	 * If this entry hit the idle task invoke ct_irq_enter() whether
 	 * RCU is watching or not.
 	 *
 	 * Interrupts can nest when the first interrupt invokes softirq
@@ -332,12 +332,12 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 	 * not nested into another interrupt.
 	 *
 	 * Checking for rcu_is_watching() here would prevent the nesting
-	 * interrupt to invoke rcu_irq_enter(). If that nested interrupt is
+	 * interrupt to invoke ct_irq_enter(). If that nested interrupt is
 	 * the tick then rcu_flavor_sched_clock_irq() would wrongfully
 	 * assume that it is the first interrupt and eventually claim
 	 * quiescent state and end grace periods prematurely.
 	 *
-	 * Unconditionally invoke rcu_irq_enter() so RCU state stays
+	 * Unconditionally invoke ct_irq_enter() so RCU state stays
 	 * consistent.
 	 *
 	 * TINY_RCU does not support EQS, so let the compiler eliminate
@@ -350,7 +350,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 		 * as in irqentry_enter_from_user_mode().
 		 */
 		lockdep_hardirqs_off(CALLER_ADDR0);
-		rcu_irq_enter();
+		ct_irq_enter();
 		instrumentation_begin();
 		trace_hardirqs_off_finish();
 		instrumentation_end();
@@ -418,7 +418,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 			trace_hardirqs_on_prepare();
 			lockdep_hardirqs_on_prepare();
 			instrumentation_end();
-			rcu_irq_exit();
+			ct_irq_exit();
 			lockdep_hardirqs_on(CALLER_ADDR0);
 			return;
 		}
@@ -436,7 +436,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 		 * was not watching on entry.
 		 */
 		if (state.exit_rcu)
-			rcu_irq_exit();
+			ct_irq_exit();
 	}
 }
 
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 9f0aef8aa9ff8..c8a6913c067d9 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -620,7 +620,7 @@ void irq_enter_rcu(void)
  */
 void irq_enter(void)
 {
-	rcu_irq_enter();
+	ct_irq_enter();
 	irq_enter_rcu();
 }
 
@@ -672,7 +672,7 @@ void irq_exit_rcu(void)
 void irq_exit(void)
 {
 	__irq_exit_rcu();
-	rcu_irq_exit();
+	ct_irq_exit();
 	 /* must be last! */
 	lockdep_hardirq_exit();
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2c95992e2c710..fe78a68181263 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3107,15 +3107,15 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx,
 	/*
 	 * When an NMI triggers, RCU is enabled via rcu_nmi_enter(),
 	 * but if the above rcu_is_watching() failed, then the NMI
-	 * triggered someplace critical, and rcu_irq_enter() should
+	 * triggered someplace critical, and ct_irq_enter() should
 	 * not be called from NMI.
 	 */
 	if (unlikely(in_nmi()))
 		return;
 
-	rcu_irq_enter_irqson();
+	ct_irq_enter_irqson();
 	__ftrace_trace_stack(buffer, trace_ctx, skip, NULL);
-	rcu_irq_exit_irqson();
+	ct_irq_exit_irqson();
 }
 
 /**
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 12/23] context_tracking: Take NMI eqs entrypoints over RCU

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

The RCU dynticks counter is going to be merged into the context tracking
subsystem. Prepare with moving the NMI extended quiescent states
entrypoints to context tracking. For now those are dumb redirection to
existing RCU calls.

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 Documentation/RCU/Design/Requirements/Requirements.rst |  2 +-
 arch/Kconfig                                           |  2 +-
 arch/arm64/kernel/entry-common.c                       |  8 ++++----
 include/linux/context_tracking_irq.h                   |  4 ++++
 include/linux/hardirq.h                                |  4 ++--
 kernel/context_tracking.c                              | 10 ++++++++++
 kernel/entry/common.c                                  |  4 ++--
 kernel/extable.c                                       |  4 ++--
 kernel/trace/trace.c                                   |  2 +-
 9 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
index 074810c739367..a0f8164c85135 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.rst
+++ b/Documentation/RCU/Design/Requirements/Requirements.rst
@@ -1847,7 +1847,7 @@ normal interrupts. One way that this can happen is for code that
 directly invokes ct_irq_enter() and ct_irq_exit() to be called
 from an NMI handler. This astonishing fact of life prompted the current
 code structure, which has ct_irq_enter() invoking
-rcu_nmi_enter() and ct_irq_exit() invoking rcu_nmi_exit().
+ct_nmi_enter() and ct_irq_exit() invoking ct_nmi_exit().
 And yes, I also learned of this requirement the hard way.
 
 Loadable Modules
diff --git a/arch/Kconfig b/arch/Kconfig
index 342642be105fc..f56f7c0e924d8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -797,7 +797,7 @@ config HAVE_CONTEXT_TRACKING_USER_OFFSTACK
 
 	  - Critical entry code isn't preemptible (or better yet:
 	    not interruptible).
-	  - No use of RCU read side critical sections, unless rcu_nmi_enter()
+	  - No use of RCU read side critical sections, unless ct_nmi_enter()
 	    got called.
 	  - No use of instrumentation, unless instrumentation_begin() got
 	    called.
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 8dabe9ec10f16..c75ca36b4a491 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -161,7 +161,7 @@ static void noinstr arm64_enter_nmi(struct pt_regs *regs)
 	__nmi_enter();
 	lockdep_hardirqs_off(CALLER_ADDR0);
 	lockdep_hardirq_enter();
-	rcu_nmi_enter();
+	ct_nmi_enter();
 
 	trace_hardirqs_off_finish();
 	ftrace_nmi_enter();
@@ -182,7 +182,7 @@ static void noinstr arm64_exit_nmi(struct pt_regs *regs)
 		lockdep_hardirqs_on_prepare();
 	}
 
-	rcu_nmi_exit();
+	ct_nmi_exit();
 	lockdep_hardirq_exit();
 	if (restore)
 		lockdep_hardirqs_on(CALLER_ADDR0);
@@ -199,7 +199,7 @@ static void noinstr arm64_enter_el1_dbg(struct pt_regs *regs)
 	regs->lockdep_hardirqs = lockdep_hardirqs_enabled();
 
 	lockdep_hardirqs_off(CALLER_ADDR0);
-	rcu_nmi_enter();
+	ct_nmi_enter();
 
 	trace_hardirqs_off_finish();
 }
@@ -218,7 +218,7 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
 		lockdep_hardirqs_on_prepare();
 	}
 
-	rcu_nmi_exit();
+	ct_nmi_exit();
 	if (restore)
 		lockdep_hardirqs_on(CALLER_ADDR0);
 }
diff --git a/include/linux/context_tracking_irq.h b/include/linux/context_tracking_irq.h
index 62f62bbd1a50d..c50b5670c4a52 100644
--- a/include/linux/context_tracking_irq.h
+++ b/include/linux/context_tracking_irq.h
@@ -7,11 +7,15 @@ void ct_irq_enter(void);
 void ct_irq_exit(void);
 void ct_irq_enter_irqson(void);
 void ct_irq_exit_irqson(void);
+void ct_nmi_enter(void);
+void ct_nmi_exit(void);
 #else
 static inline void ct_irq_enter(void) { }
 static inline void ct_irq_exit(void) { }
 static inline void ct_irq_enter_irqson(void) { }
 static inline void ct_irq_exit_irqson(void) { }
+static inline void ct_nmi_enter(void) { }
+static inline void ct_nmi_exit(void) { }
 #endif
 
 #endif
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 76878b357ffa9..345cdbe9c1b70 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -124,7 +124,7 @@ extern void rcu_nmi_exit(void);
 	do {							\
 		__nmi_enter();					\
 		lockdep_hardirq_enter();			\
-		rcu_nmi_enter();				\
+		ct_nmi_enter();				\
 		instrumentation_begin();			\
 		ftrace_nmi_enter();				\
 		instrumentation_end();				\
@@ -143,7 +143,7 @@ extern void rcu_nmi_exit(void);
 		instrumentation_begin();			\
 		ftrace_nmi_exit();				\
 		instrumentation_end();				\
-		rcu_nmi_exit();					\
+		ct_nmi_exit();					\
 		lockdep_hardirq_exit();				\
 		__nmi_exit();					\
 	} while (0)
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 891464f7aa5a4..afb4451c26a25 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -55,6 +55,16 @@ void ct_irq_exit_irqson(void)
 {
 	rcu_irq_exit_irqson();
 }
+
+noinstr void ct_nmi_enter(void)
+{
+	rcu_nmi_enter();
+}
+
+noinstr void ct_nmi_exit(void)
+{
+	rcu_nmi_exit();
+}
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
 #ifdef CONFIG_CONTEXT_TRACKING_USER
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 667ba5d581ff7..063068a9ea9b3 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -449,7 +449,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
 	__nmi_enter();
 	lockdep_hardirqs_off(CALLER_ADDR0);
 	lockdep_hardirq_enter();
-	rcu_nmi_enter();
+	ct_nmi_enter();
 
 	instrumentation_begin();
 	trace_hardirqs_off_finish();
@@ -469,7 +469,7 @@ void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
 	}
 	instrumentation_end();
 
-	rcu_nmi_exit();
+	ct_nmi_exit();
 	lockdep_hardirq_exit();
 	if (irq_state.lockdep)
 		lockdep_hardirqs_on(CALLER_ADDR0);
diff --git a/kernel/extable.c b/kernel/extable.c
index bda5e97615418..71f482581cab4 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -114,7 +114,7 @@ int kernel_text_address(unsigned long addr)
 
 	/* Treat this like an NMI as it can happen anywhere */
 	if (no_rcu)
-		rcu_nmi_enter();
+		ct_nmi_enter();
 
 	if (is_module_text_address(addr))
 		goto out;
@@ -127,7 +127,7 @@ int kernel_text_address(unsigned long addr)
 	ret = 0;
 out:
 	if (no_rcu)
-		rcu_nmi_exit();
+		ct_nmi_exit();
 
 	return ret;
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index fe78a68181263..5fc7f17f5ec7b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3105,7 +3105,7 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx,
 	}
 
 	/*
-	 * When an NMI triggers, RCU is enabled via rcu_nmi_enter(),
+	 * When an NMI triggers, RCU is enabled via ct_nmi_enter(),
 	 * but if the above rcu_is_watching() failed, then the NMI
 	 * triggered someplace critical, and ct_irq_enter() should
 	 * not be called from NMI.
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 13/23] rcu/context-tracking: Remove rcu_irq_enter/exit()

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Now rcu_irq_enter/exit() is an unecessary middle call between
ct_irq_enter/exit() and nmi_irq_enter/exit(). Take this opportunity
to remove the former functions and move the comments above them to the
new entrypoints.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/rcutiny.h   |  4 --
 include/linux/rcutree.h   |  4 --
 kernel/context_tracking.c | 71 +++++++++++++++++++++++++++++++--
 kernel/rcu/tree.c         | 83 ---------------------------------------
 4 files changed, 67 insertions(+), 95 deletions(-)

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 5fed476f977f6..591119413cf1d 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -78,10 +78,6 @@ static inline void rcu_cpu_stall_reset(void) { }
 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
 static inline void rcu_idle_enter(void) { }
 static inline void rcu_idle_exit(void) { }
-static inline void rcu_irq_enter(void) { }
-static inline void rcu_irq_exit_irqson(void) { }
-static inline void rcu_irq_enter_irqson(void) { }
-static inline void rcu_irq_exit(void) { }
 static inline void rcu_irq_exit_check_preempt(void) { }
 #define rcu_is_idle_cpu(cpu) \
 	(is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq())
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 9c6cfb742504f..4522b6a7cc42f 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -47,10 +47,6 @@ void cond_synchronize_rcu(unsigned long oldstate);
 
 void rcu_idle_enter(void);
 void rcu_idle_exit(void);
-void rcu_irq_enter(void);
-void rcu_irq_exit(void);
-void rcu_irq_enter_irqson(void);
-void rcu_irq_exit_irqson(void);
 bool rcu_is_idle_cpu(int cpu);
 
 #ifdef CONFIG_PROVE_RCU
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index afb4451c26a25..96406daf5f54b 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -36,24 +36,87 @@ void ct_idle_exit(void)
 }
 EXPORT_SYMBOL_GPL(ct_idle_exit);
 
+/**
+ * ct_irq_enter - inform RCU that current CPU is entering irq away from idle
+ *
+ * Enter an interrupt handler, which might possibly result in exiting
+ * idle mode, in other words, entering the mode in which read-side critical
+ * sections can occur.  The caller must have disabled interrupts.
+ *
+ * Note that the Linux kernel is fully capable of entering an interrupt
+ * handler that it never exits, for example when doing upcalls to user mode!
+ * This code assumes that the idle loop never does upcalls to user mode.
+ * If your architecture's idle loop does do upcalls to user mode (or does
+ * anything else that results in unbalanced calls to the irq_enter() and
+ * irq_exit() functions), RCU will give you what you deserve, good and hard.
+ * But very infrequently and irreproducibly.
+ *
+ * Use things like work queues to work around this limitation.
+ *
+ * You have been warned.
+ *
+ * If you add or remove a call to ct_irq_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
+ */
 noinstr void ct_irq_enter(void)
 {
-	rcu_irq_enter();
+	lockdep_assert_irqs_disabled();
+	ct_nmi_enter();
 }
 
+/**
+ * ct_irq_exit - inform RCU that current CPU is exiting irq towards idle
+ *
+ * Exit from an interrupt handler, which might possibly result in entering
+ * idle mode, in other words, leaving the mode in which read-side critical
+ * sections can occur.  The caller must have disabled interrupts.
+ *
+ * This code assumes that the idle loop never does anything that might
+ * result in unbalanced calls to irq_enter() and irq_exit().  If your
+ * architecture's idle loop violates this assumption, RCU will give you what
+ * you deserve, good and hard.  But very infrequently and irreproducibly.
+ *
+ * Use things like work queues to work around this limitation.
+ *
+ * You have been warned.
+ *
+ * If you add or remove a call to ct_irq_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
+ */
 noinstr void ct_irq_exit(void)
 {
-	rcu_irq_exit();
+	lockdep_assert_irqs_disabled();
+	ct_nmi_exit();
 }
 
+/*
+ * Wrapper for ct_irq_enter() where interrupts are enabled.
+ *
+ * If you add or remove a call to ct_irq_enter_irqson(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
+ */
 void ct_irq_enter_irqson(void)
 {
-	rcu_irq_enter_irqson();
+	unsigned long flags;
+
+	local_irq_save(flags);
+	ct_irq_enter();
+	local_irq_restore(flags);
 }
 
+/*
+ * Wrapper for ct_irq_exit() where interrupts are enabled.
+ *
+ * If you add or remove a call to ct_irq_exit_irqson(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
+ */
 void ct_irq_exit_irqson(void)
 {
-	rcu_irq_exit_irqson();
+	unsigned long flags;
+
+	local_irq_save(flags);
+	ct_irq_exit();
+	local_irq_restore(flags);
 }
 
 noinstr void ct_nmi_enter(void)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 051fed0844b67..75b433dba4276 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -789,31 +789,6 @@ noinstr void rcu_nmi_exit(void)
 		rcu_dynticks_task_enter();
 }
 
-/**
- * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
- *
- * Exit from an interrupt handler, which might possibly result in entering
- * idle mode, in other words, leaving the mode in which read-side critical
- * sections can occur.  The caller must have disabled interrupts.
- *
- * This code assumes that the idle loop never does anything that might
- * result in unbalanced calls to irq_enter() and irq_exit().  If your
- * architecture's idle loop violates this assumption, RCU will give you what
- * you deserve, good and hard.  But very infrequently and irreproducibly.
- *
- * Use things like work queues to work around this limitation.
- *
- * You have been warned.
- *
- * If you add or remove a call to rcu_irq_exit(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-void noinstr rcu_irq_exit(void)
-{
-	lockdep_assert_irqs_disabled();
-	rcu_nmi_exit();
-}
-
 #ifdef CONFIG_PROVE_RCU
 /**
  * rcu_irq_exit_check_preempt - Validate that scheduling is possible
@@ -832,21 +807,6 @@ void rcu_irq_exit_check_preempt(void)
 }
 #endif /* #ifdef CONFIG_PROVE_RCU */
 
-/*
- * Wrapper for rcu_irq_exit() where interrupts are enabled.
- *
- * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
- * with CONFIG_RCU_EQS_DEBUG=y.
- */
-void rcu_irq_exit_irqson(void)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	rcu_irq_exit();
-	local_irq_restore(flags);
-}
-
 /*
  * Exit an RCU extended quiescent state, which can be either the
  * idle loop or adaptive-tickless usermode execution.
@@ -1041,49 +1001,6 @@ noinstr void rcu_nmi_enter(void)
 	barrier();
 }
 
-/**
- * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
- *
- * Enter an interrupt handler, which might possibly result in exiting
- * idle mode, in other words, entering the mode in which read-side critical
- * sections can occur.  The caller must have disabled interrupts.
- *
- * Note that the Linux kernel is fully capable of entering an interrupt
- * handler that it never exits, for example when doing upcalls to user mode!
- * This code assumes that the idle loop never does upcalls to user mode.
- * If your architecture's idle loop does do upcalls to user mode (or does
- * anything else that results in unbalanced calls to the irq_enter() and
- * irq_exit() functions), RCU will give you what you deserve, good and hard.
- * But very infrequently and irreproducibly.
- *
- * Use things like work queues to work around this limitation.
- *
- * You have been warned.
- *
- * If you add or remove a call to rcu_irq_enter(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-noinstr void rcu_irq_enter(void)
-{
-	lockdep_assert_irqs_disabled();
-	rcu_nmi_enter();
-}
-
-/*
- * Wrapper for rcu_irq_enter() where interrupts are enabled.
- *
- * If you add or remove a call to rcu_irq_enter_irqson(), be sure to test
- * with CONFIG_RCU_EQS_DEBUG=y.
- */
-void rcu_irq_enter_irqson(void)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	rcu_irq_enter();
-	local_irq_restore(flags);
-}
-
 /*
  * Check to see if any future non-offloaded RCU-related work will need
  * to be done by the current CPU, even if none need be done immediately,
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 14/23] rcu/context_tracking: Move dynticks counter to context tracking

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

In order to prepare for merging RCU dynticks counter into the context
tracking state, move the rcu_data's dynticks field to the context
tracking structure. It will later be mixed within the context tracking
state itself.

[ paulmck: Move enum ctx_state into global scope. ]

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking_state.h | 43 ++++++++++++++++----
 kernel/context_tracking.c              | 10 +++--
 kernel/rcu/tree.c                      | 56 +++++++++++++-------------
 kernel/rcu/tree.h                      |  1 -
 kernel/rcu/tree_exp.h                  |  2 +-
 kernel/rcu/tree_stall.h                |  4 +-
 6 files changed, 73 insertions(+), 43 deletions(-)

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 9c16a8b2c1947..6d50d08b4933a 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -6,7 +6,15 @@
 #include <linux/static_key.h>
 #include <linux/context_tracking_irq.h>
 
+enum ctx_state {
+	CONTEXT_DISABLED = -1,	/* returned by ct_state() if unknown */
+	CONTEXT_KERNEL = 0,
+	CONTEXT_USER,
+	CONTEXT_GUEST,
+};
+
 struct context_tracking {
+#ifdef CONFIG_CONTEXT_TRACKING_USER
 	/*
 	 * When active is false, probes are unset in order
 	 * to minimize overhead: TIF flags are cleared
@@ -15,17 +23,38 @@ struct context_tracking {
 	 */
 	bool active;
 	int recursion;
-	enum ctx_state {
-		CONTEXT_DISABLED = -1,	/* returned by ct_state() if unknown */
-		CONTEXT_KERNEL = 0,
-		CONTEXT_USER,
-		CONTEXT_GUEST,
-	} state;
+	enum ctx_state state;
+#endif
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+	atomic_t dynticks;		/* Even value for idle, else odd. */
+#endif
 };
 
+#ifdef CONFIG_CONTEXT_TRACKING
+DECLARE_PER_CPU(struct context_tracking, context_tracking);
+#endif
+
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+static __always_inline int ct_dynticks(void)
+{
+	return atomic_read(this_cpu_ptr(&context_tracking.dynticks));
+}
+
+static __always_inline int ct_dynticks_cpu(int cpu)
+{
+	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+	return atomic_read(&ct->dynticks);
+}
+
+static __always_inline int ct_dynticks_cpu_acquire(int cpu)
+{
+	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+	return atomic_read_acquire(&ct->dynticks);
+}
+#endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
+
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 extern struct static_key_false context_tracking_key;
-DECLARE_PER_CPU(struct context_tracking, context_tracking);
 
 static __always_inline bool context_tracking_enabled(void)
 {
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 96406daf5f54b..22b4ee56a7c97 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -23,6 +23,13 @@
 #include <linux/kprobes.h>
 
 
+DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+	.dynticks = ATOMIC_INIT(1),
+#endif
+};
+EXPORT_SYMBOL_GPL(context_tracking);
+
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 noinstr void ct_idle_enter(void)
 {
@@ -138,9 +145,6 @@ noinstr void ct_nmi_exit(void)
 DEFINE_STATIC_KEY_FALSE(context_tracking_key);
 EXPORT_SYMBOL_GPL(context_tracking_key);
 
-DEFINE_PER_CPU(struct context_tracking, context_tracking);
-EXPORT_SYMBOL_GPL(context_tracking);
-
 static noinstr bool context_tracking_recursion_enter(void)
 {
 	int recursion;
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 75b433dba4276..a471edc3d8938 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -77,7 +77,6 @@
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
 	.dynticks_nesting = 1,
 	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
-	.dynticks = ATOMIC_INIT(1),
 #ifdef CONFIG_RCU_NOCB_CPU
 	.cblist.flags = SEGCBLIST_RCU_CORE,
 #endif
@@ -268,7 +267,7 @@ void rcu_softirq_qs(void)
  */
 static noinline noinstr unsigned long rcu_dynticks_inc(int incby)
 {
-	return arch_atomic_add_return(incby, this_cpu_ptr(&rcu_data.dynticks));
+	return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynticks));
 }
 
 /*
@@ -324,9 +323,7 @@ static noinstr void rcu_dynticks_eqs_exit(void)
  */
 static void rcu_dynticks_eqs_online(void)
 {
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
-
-	if (atomic_read(&rdp->dynticks) & 0x1)
+	if (ct_dynticks() & 0x1)
 		return;
 	rcu_dynticks_inc(1);
 }
@@ -338,17 +335,17 @@ static void rcu_dynticks_eqs_online(void)
  */
 static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
 {
-	return !(arch_atomic_read(this_cpu_ptr(&rcu_data.dynticks)) & 0x1);
+	return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1);
 }
 
 /*
  * Snapshot the ->dynticks counter with full ordering so as to allow
  * stable comparison of this counter with past and future snapshots.
  */
-static int rcu_dynticks_snap(struct rcu_data *rdp)
+static int rcu_dynticks_snap(int cpu)
 {
 	smp_mb();  // Fundamental RCU ordering guarantee.
-	return atomic_read_acquire(&rdp->dynticks);
+	return ct_dynticks_cpu_acquire(cpu);
 }
 
 /*
@@ -363,9 +360,7 @@ static bool rcu_dynticks_in_eqs(int snap)
 /* Return true if the specified CPU is currently idle from an RCU viewpoint.  */
 bool rcu_is_idle_cpu(int cpu)
 {
-	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
-
-	return rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp));
+	return rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu));
 }
 
 /*
@@ -375,7 +370,7 @@ bool rcu_is_idle_cpu(int cpu)
  */
 static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
 {
-	return snap != rcu_dynticks_snap(rdp);
+	return snap != rcu_dynticks_snap(rdp->cpu);
 }
 
 /*
@@ -384,11 +379,10 @@ static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
  */
 bool rcu_dynticks_zero_in_eqs(int cpu, int *vp)
 {
-	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	int snap;
 
 	// If not quiescent, force back to earlier extended quiescent state.
-	snap = atomic_read(&rdp->dynticks) & ~0x1;
+	snap = ct_dynticks_cpu(cpu) & ~0x1;
 
 	smp_rmb(); // Order ->dynticks and *vp reads.
 	if (READ_ONCE(*vp))
@@ -396,7 +390,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp)
 	smp_rmb(); // Order *vp read and ->dynticks re-read.
 
 	// If still in the same extended quiescent state, we are good!
-	return snap == atomic_read(&rdp->dynticks);
+	return snap == ct_dynticks_cpu(cpu);
 }
 
 /*
@@ -620,6 +614,7 @@ EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
 static noinstr void rcu_eqs_enter(bool user)
 {
 	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
 	WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
 	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
@@ -633,12 +628,12 @@ static noinstr void rcu_eqs_enter(bool user)
 
 	instrumentation_begin();
 	lockdep_assert_irqs_disabled();
-	trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks));
+	trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	rcu_preempt_deferred_qs(current);
 
 	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
-	instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
 	instrumentation_end();
 	WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
@@ -740,7 +735,7 @@ noinstr void rcu_user_enter(void)
  * rcu_nmi_exit - inform RCU of exit from NMI context
  *
  * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update rdp->dynticks and rdp->dynticks_nmi_nesting
+ * RCU-idle period, update ct->dynticks and rdp->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
@@ -749,6 +744,7 @@ noinstr void rcu_user_enter(void)
  */
 noinstr void rcu_nmi_exit(void)
 {
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 
 	instrumentation_begin();
@@ -766,7 +762,7 @@ noinstr void rcu_nmi_exit(void)
 	 */
 	if (rdp->dynticks_nmi_nesting != 1) {
 		trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2,
-				  atomic_read(&rdp->dynticks));
+				  ct_dynticks());
 		WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
 			   rdp->dynticks_nmi_nesting - 2);
 		instrumentation_end();
@@ -774,11 +770,11 @@ noinstr void rcu_nmi_exit(void)
 	}
 
 	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-	trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks));
+	trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, ct_dynticks());
 	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 
 	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
-	instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 	instrumentation_end();
 
 	// RCU is watching here ...
@@ -817,6 +813,7 @@ void rcu_irq_exit_check_preempt(void)
  */
 static void noinstr rcu_eqs_exit(bool user)
 {
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 	struct rcu_data *rdp;
 	long oldval;
 
@@ -836,9 +833,9 @@ static void noinstr rcu_eqs_exit(bool user)
 	instrumentation_begin();
 
 	// instrumentation for the noinstr rcu_dynticks_eqs_exit()
-	instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
-	trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, atomic_read(&rdp->dynticks));
+	trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	WRITE_ONCE(rdp->dynticks_nesting, 1);
 	WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
@@ -944,7 +941,7 @@ void __rcu_irq_enter_check_tick(void)
 /**
  * rcu_nmi_enter - inform RCU of entry to NMI context
  *
- * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and
+ * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
  * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know
  * that the CPU is active.  This implementation permits nested NMIs, as
  * long as the nesting level does not overflow an int.  (You will probably
@@ -957,6 +954,7 @@ noinstr void rcu_nmi_enter(void)
 {
 	long incby = 2;
 	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
 	/* Complain about underflow. */
 	WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0);
@@ -980,9 +978,9 @@ noinstr void rcu_nmi_enter(void)
 
 		instrumentation_begin();
 		// instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs()
-		instrument_atomic_read(&rdp->dynticks, sizeof(rdp->dynticks));
+		instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks));
 		// instrumentation for the noinstr rcu_dynticks_eqs_exit()
-		instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+		instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
 		incby = 1;
 	} else if (!in_nmi()) {
@@ -994,7 +992,7 @@ noinstr void rcu_nmi_enter(void)
 
 	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
 			  rdp->dynticks_nmi_nesting,
-			  rdp->dynticks_nmi_nesting + incby, atomic_read(&rdp->dynticks));
+			  rdp->dynticks_nmi_nesting + incby, ct_dynticks());
 	instrumentation_end();
 	WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
 		   rdp->dynticks_nmi_nesting + incby);
@@ -1138,7 +1136,7 @@ static void rcu_gpnum_ovf(struct rcu_node *rnp, struct rcu_data *rdp)
  */
 static int dyntick_save_progress_counter(struct rcu_data *rdp)
 {
-	rdp->dynticks_snap = rcu_dynticks_snap(rdp);
+	rdp->dynticks_snap = rcu_dynticks_snap(rdp->cpu);
 	if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
 		trace_rcu_fqs(rcu_state.name, rdp->gp_seq, rdp->cpu, TPS("dti"));
 		rcu_gpnum_ovf(rdp->mynode, rdp);
@@ -4142,7 +4140,7 @@ rcu_boot_init_percpu_data(int cpu)
 	rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
 	INIT_WORK(&rdp->strict_work, strict_work_handler);
 	WARN_ON_ONCE(rdp->dynticks_nesting != 1);
-	WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)));
+	WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)));
 	rdp->barrier_seq_snap = rcu_state.barrier_sequence;
 	rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
 	rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 2ccf5845957df..ebb973f5b1900 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -189,7 +189,6 @@ struct rcu_data {
 	int dynticks_snap;		/* Per-GP tracking for dynticks. */
 	long dynticks_nesting;		/* Track process nesting level. */
 	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
-	atomic_t dynticks;		/* Even value for idle, else odd. */
 	bool rcu_need_heavy_qs;		/* GP old, so heavy quiescent state! */
 	bool rcu_urgent_qs;		/* GP old need light quiescent state. */
 	bool rcu_forced_tick;		/* Forced tick to provide QS. */
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 0f70f62039a90..75c22d1034c1e 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -356,7 +356,7 @@ static void __sync_rcu_exp_select_node_cpus(struct rcu_exp_work *rewp)
 		    !(rnp->qsmaskinitnext & mask)) {
 			mask_ofl_test |= mask;
 		} else {
-			snap = rcu_dynticks_snap(rdp);
+			snap = rcu_dynticks_snap(cpu);
 			if (rcu_dynticks_in_eqs(snap))
 				mask_ofl_test |= mask;
 			else
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 3556637768fd5..250fbf2e8522f 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -465,7 +465,7 @@ static void print_cpu_stall_info(int cpu)
 	}
 	delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
 	falsepositive = rcu_is_gp_kthread_starving(NULL) &&
-			rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp));
+			rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu));
 	rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j);
 	if (rcuc_starved)
 		sprintf(buf, " rcuc=%ld jiffies(starved)", j);
@@ -478,7 +478,7 @@ static void print_cpu_stall_info(int cpu)
 			rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
 				"!."[!delta],
 	       ticks_value, ticks_title,
-	       rcu_dynticks_snap(rdp) & 0xfff,
+	       rcu_dynticks_snap(cpu) & 0xfff,
 	       rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
 	       rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
 	       data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 15/23] rcu/context_tracking: Move dynticks_nesting to context tracking

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

The RCU eqs tracking is going to be performed by the context tracking
subsystem. The related nesting counters thus need to be moved to the
context tracking structure.

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking_state.h | 12 ++++++++++
 kernel/context_tracking.c              |  1 +
 kernel/rcu/tree.c                      | 31 +++++++++++++-------------
 kernel/rcu/tree.h                      |  1 -
 kernel/rcu/tree_stall.h                |  2 +-
 5 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 6d50d08b4933a..c866701c7edb5 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -27,6 +27,7 @@ struct context_tracking {
 #endif
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	atomic_t dynticks;		/* Even value for idle, else odd. */
+	long dynticks_nesting;		/* Track process nesting level. */
 #endif
 };
 
@@ -51,6 +52,17 @@ static __always_inline int ct_dynticks_cpu_acquire(int cpu)
 	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
 	return atomic_read_acquire(&ct->dynticks);
 }
+
+static __always_inline long ct_dynticks_nesting(void)
+{
+	return __this_cpu_read(context_tracking.dynticks_nesting);
+}
+
+static __always_inline long ct_dynticks_nesting_cpu(int cpu)
+{
+	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+	return ct->dynticks_nesting;
+}
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
 #ifdef CONFIG_CONTEXT_TRACKING_USER
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 22b4ee56a7c97..ed6c062aff9fa 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -25,6 +25,7 @@
 
 DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
+	.dynticks_nesting = 1,
 	.dynticks = ATOMIC_INIT(1),
 #endif
 };
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a471edc3d8938..f6bf328bb9cfd 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -75,7 +75,6 @@
 /* Data structures. */
 
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
-	.dynticks_nesting = 1,
 	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
 #ifdef CONFIG_RCU_NOCB_CPU
 	.cblist.flags = SEGCBLIST_RCU_CORE,
@@ -436,7 +435,7 @@ static int rcu_is_cpu_rrupt_from_idle(void)
 	lockdep_assert_irqs_disabled();
 
 	/* Check for counter underflows */
-	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0,
+	RCU_LOCKDEP_WARN(ct_dynticks_nesting() < 0,
 			 "RCU dynticks_nesting counter underflow!");
 	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0,
 			 "RCU dynticks_nmi_nesting counter underflow/zero!");
@@ -452,7 +451,7 @@ static int rcu_is_cpu_rrupt_from_idle(void)
 	WARN_ON_ONCE(!nesting && !is_idle_task(current));
 
 	/* Does CPU appear to be idle from an RCU standpoint? */
-	return __this_cpu_read(rcu_data.dynticks_nesting) == 0;
+	return ct_dynticks_nesting() == 0;
 }
 
 #define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1000 : 10)
@@ -619,16 +618,16 @@ static noinstr void rcu_eqs_enter(bool user)
 	WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
 	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-		     rdp->dynticks_nesting == 0);
-	if (rdp->dynticks_nesting != 1) {
+		     ct_dynticks_nesting() == 0);
+	if (ct_dynticks_nesting() != 1) {
 		// RCU will still be watching, so just do accounting and leave.
-		rdp->dynticks_nesting--;
+		ct->dynticks_nesting--;
 		return;
 	}
 
 	instrumentation_begin();
 	lockdep_assert_irqs_disabled();
-	trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, ct_dynticks());
+	trace_rcu_dyntick(TPS("Start"), ct_dynticks_nesting(), 0, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	rcu_preempt_deferred_qs(current);
 
@@ -636,7 +635,7 @@ static noinstr void rcu_eqs_enter(bool user)
 	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
 	instrumentation_end();
-	WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
+	WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */
 	// RCU is watching here ...
 	rcu_dynticks_eqs_enter();
 	// ... but is no longer watching here.
@@ -793,7 +792,7 @@ void rcu_irq_exit_check_preempt(void)
 {
 	lockdep_assert_irqs_disabled();
 
-	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0,
+	RCU_LOCKDEP_WARN(ct_dynticks_nesting() <= 0,
 			 "RCU dynticks_nesting counter underflow/zero!");
 	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=
 			 DYNTICK_IRQ_NONIDLE,
@@ -819,11 +818,11 @@ static void noinstr rcu_eqs_exit(bool user)
 
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
 	rdp = this_cpu_ptr(&rcu_data);
-	oldval = rdp->dynticks_nesting;
+	oldval = ct_dynticks_nesting();
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
 	if (oldval) {
 		// RCU was already watching, so just do accounting and leave.
-		rdp->dynticks_nesting++;
+		ct->dynticks_nesting++;
 		return;
 	}
 	rcu_dynticks_task_exit();
@@ -835,9 +834,9 @@ static void noinstr rcu_eqs_exit(bool user)
 	// instrumentation for the noinstr rcu_dynticks_eqs_exit()
 	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
-	trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, ct_dynticks());
+	trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
-	WRITE_ONCE(rdp->dynticks_nesting, 1);
+	WRITE_ONCE(ct->dynticks_nesting, 1);
 	WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
 	WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
 	instrumentation_end();
@@ -4134,12 +4133,13 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
 static void __init
 rcu_boot_init_percpu_data(int cpu)
 {
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 
 	/* Set up local state, ensuring consistent view of global state. */
 	rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
 	INIT_WORK(&rdp->strict_work, strict_work_handler);
-	WARN_ON_ONCE(rdp->dynticks_nesting != 1);
+	WARN_ON_ONCE(ct->dynticks_nesting != 1);
 	WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)));
 	rdp->barrier_seq_snap = rcu_state.barrier_sequence;
 	rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
@@ -4164,6 +4164,7 @@ rcu_boot_init_percpu_data(int cpu)
 int rcutree_prepare_cpu(unsigned int cpu)
 {
 	unsigned long flags;
+	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
 	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	struct rcu_node *rnp = rcu_get_root();
 
@@ -4172,7 +4173,7 @@ int rcutree_prepare_cpu(unsigned int cpu)
 	rdp->qlen_last_fqs_check = 0;
 	rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
 	rdp->blimit = blimit;
-	rdp->dynticks_nesting = 1;	/* CPU not up, no tearing. */
+	ct->dynticks_nesting = 1;	/* CPU not up, no tearing. */
 	raw_spin_unlock_rcu_node(rnp);		/* irqs remain disabled. */
 
 	/*
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index ebb973f5b1900..650ff3cf01219 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -187,7 +187,6 @@ struct rcu_data {
 
 	/* 3) dynticks interface. */
 	int dynticks_snap;		/* Per-GP tracking for dynticks. */
-	long dynticks_nesting;		/* Track process nesting level. */
 	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
 	bool rcu_need_heavy_qs;		/* GP old, so heavy quiescent state! */
 	bool rcu_urgent_qs;		/* GP old need light quiescent state. */
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 250fbf2e8522f..a9c82254b6c65 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -479,7 +479,7 @@ static void print_cpu_stall_info(int cpu)
 				"!."[!delta],
 	       ticks_value, ticks_title,
 	       rcu_dynticks_snap(cpu) & 0xfff,
-	       rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
+	       ct_dynticks_nesting_cpu(cpu), rdp->dynticks_nmi_nesting,
 	       rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
 	       data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
 	       rcuc_starved ? buf : "",
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 16/23] rcu/context_tracking: Move dynticks_nmi_nesting to context tracking

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

The RCU eqs tracking is going to be performed by the context tracking
subsystem. The related nesting counters thus need to be moved to the
context tracking structure.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking_state.h | 15 ++++++++
 kernel/context_tracking.c              |  1 +
 kernel/rcu/rcu.h                       |  4 ---
 kernel/rcu/tree.c                      | 48 +++++++++++---------------
 kernel/rcu/tree.h                      |  1 -
 kernel/rcu/tree_stall.h                |  2 +-
 6 files changed, 38 insertions(+), 33 deletions(-)

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index c866701c7edb5..2f957b48e24f9 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -13,6 +13,9 @@ enum ctx_state {
 	CONTEXT_GUEST,
 };
 
+/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
+#define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
+
 struct context_tracking {
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 	/*
@@ -28,6 +31,7 @@ struct context_tracking {
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	atomic_t dynticks;		/* Even value for idle, else odd. */
 	long dynticks_nesting;		/* Track process nesting level. */
+	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
 #endif
 };
 
@@ -63,6 +67,17 @@ static __always_inline long ct_dynticks_nesting_cpu(int cpu)
 	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
 	return ct->dynticks_nesting;
 }
+
+static __always_inline long ct_dynticks_nmi_nesting(void)
+{
+	return __this_cpu_read(context_tracking.dynticks_nmi_nesting);
+}
+
+static __always_inline long ct_dynticks_nmi_nesting_cpu(int cpu)
+{
+	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+	return ct->dynticks_nmi_nesting;
+}
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
 #ifdef CONFIG_CONTEXT_TRACKING_USER
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index ed6c062aff9fa..bf5f498b21d39 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -26,6 +26,7 @@
 DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	.dynticks_nesting = 1,
+	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
 	.dynticks = ATOMIC_INIT(1),
 #endif
 };
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 4916077119f3f..7b4a88deff9ad 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -12,10 +12,6 @@
 
 #include <trace/events/rcu.h>
 
-/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
-#define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
-
-
 /*
  * Grace-period counter management.
  */
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f6bf328bb9cfd..006939b29e823 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -75,7 +75,6 @@
 /* Data structures. */
 
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
-	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
 #ifdef CONFIG_RCU_NOCB_CPU
 	.cblist.flags = SEGCBLIST_RCU_CORE,
 #endif
@@ -437,11 +436,11 @@ static int rcu_is_cpu_rrupt_from_idle(void)
 	/* Check for counter underflows */
 	RCU_LOCKDEP_WARN(ct_dynticks_nesting() < 0,
 			 "RCU dynticks_nesting counter underflow!");
-	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0,
+	RCU_LOCKDEP_WARN(ct_dynticks_nmi_nesting() <= 0,
 			 "RCU dynticks_nmi_nesting counter underflow/zero!");
 
 	/* Are we at first interrupt nesting level? */
-	nesting = __this_cpu_read(rcu_data.dynticks_nmi_nesting);
+	nesting = ct_dynticks_nmi_nesting();
 	if (nesting > 1)
 		return false;
 
@@ -612,11 +611,10 @@ EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
  */
 static noinstr void rcu_eqs_enter(bool user)
 {
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() != DYNTICK_IRQ_NONIDLE);
+	WRITE_ONCE(ct->dynticks_nmi_nesting, 0);
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
 		     ct_dynticks_nesting() == 0);
 	if (ct_dynticks_nesting() != 1) {
@@ -734,7 +732,7 @@ noinstr void rcu_user_enter(void)
  * rcu_nmi_exit - inform RCU of exit from NMI context
  *
  * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update ct->dynticks and rdp->dynticks_nmi_nesting
+ * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
@@ -744,7 +742,6 @@ noinstr void rcu_user_enter(void)
 noinstr void rcu_nmi_exit(void)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 
 	instrumentation_begin();
 	/*
@@ -752,25 +749,25 @@ noinstr void rcu_nmi_exit(void)
 	 * (We are exiting an NMI handler, so RCU better be paying attention
 	 * to us!)
 	 */
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting <= 0);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() <= 0);
 	WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
 
 	/*
 	 * If the nesting level is not 1, the CPU wasn't RCU-idle, so
 	 * leave it in non-RCU-idle state.
 	 */
-	if (rdp->dynticks_nmi_nesting != 1) {
-		trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2,
+	if (ct_dynticks_nmi_nesting() != 1) {
+		trace_rcu_dyntick(TPS("--="), ct_dynticks_nmi_nesting(), ct_dynticks_nmi_nesting() - 2,
 				  ct_dynticks());
-		WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
-			   rdp->dynticks_nmi_nesting - 2);
+		WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */
+			   ct_dynticks_nmi_nesting() - 2);
 		instrumentation_end();
 		return;
 	}
 
 	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-	trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, ct_dynticks());
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
+	trace_rcu_dyntick(TPS("Startirq"), ct_dynticks_nmi_nesting(), 0, ct_dynticks());
+	WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 
 	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
 	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
@@ -794,7 +791,7 @@ void rcu_irq_exit_check_preempt(void)
 
 	RCU_LOCKDEP_WARN(ct_dynticks_nesting() <= 0,
 			 "RCU dynticks_nesting counter underflow/zero!");
-	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=
+	RCU_LOCKDEP_WARN(ct_dynticks_nmi_nesting() !=
 			 DYNTICK_IRQ_NONIDLE,
 			 "Bad RCU  dynticks_nmi_nesting counter\n");
 	RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(),
@@ -813,11 +810,9 @@ void rcu_irq_exit_check_preempt(void)
 static void noinstr rcu_eqs_exit(bool user)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-	struct rcu_data *rdp;
 	long oldval;
 
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
-	rdp = this_cpu_ptr(&rcu_data);
 	oldval = ct_dynticks_nesting();
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
 	if (oldval) {
@@ -837,8 +832,8 @@ static void noinstr rcu_eqs_exit(bool user)
 	trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	WRITE_ONCE(ct->dynticks_nesting, 1);
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting());
+	WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
 	instrumentation_end();
 }
 
@@ -941,7 +936,7 @@ void __rcu_irq_enter_check_tick(void)
  * rcu_nmi_enter - inform RCU of entry to NMI context
  *
  * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
- * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know
+ * ct->dynticks_nmi_nesting to let the RCU grace-period handling know
  * that the CPU is active.  This implementation permits nested NMIs, as
  * long as the nesting level does not overflow an int.  (You will probably
  * run out of stack space first.)
@@ -952,11 +947,10 @@ void __rcu_irq_enter_check_tick(void)
 noinstr void rcu_nmi_enter(void)
 {
 	long incby = 2;
-	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
 	/* Complain about underflow. */
-	WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() < 0);
 
 	/*
 	 * If idle from RCU viewpoint, atomically increment ->dynticks
@@ -990,11 +984,11 @@ noinstr void rcu_nmi_enter(void)
 	}
 
 	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
-			  rdp->dynticks_nmi_nesting,
-			  rdp->dynticks_nmi_nesting + incby, ct_dynticks());
+			  ct_dynticks_nmi_nesting(),
+			  ct_dynticks_nmi_nesting() + incby, ct_dynticks());
 	instrumentation_end();
-	WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
-		   rdp->dynticks_nmi_nesting + incby);
+	WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */
+		   ct_dynticks_nmi_nesting() + incby);
 	barrier();
 }
 
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 650ff3cf01219..72dbf8512ce78 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -187,7 +187,6 @@ struct rcu_data {
 
 	/* 3) dynticks interface. */
 	int dynticks_snap;		/* Per-GP tracking for dynticks. */
-	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
 	bool rcu_need_heavy_qs;		/* GP old, so heavy quiescent state! */
 	bool rcu_urgent_qs;		/* GP old need light quiescent state. */
 	bool rcu_forced_tick;		/* Forced tick to provide QS. */
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index a9c82254b6c65..2683ce0a7c724 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -479,7 +479,7 @@ static void print_cpu_stall_info(int cpu)
 				"!."[!delta],
 	       ticks_value, ticks_title,
 	       rcu_dynticks_snap(cpu) & 0xfff,
-	       ct_dynticks_nesting_cpu(cpu), rdp->dynticks_nmi_nesting,
+	       ct_dynticks_nesting_cpu(cpu), ct_dynticks_nmi_nesting_cpu(cpu),
 	       rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
 	       data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
 	       rcuc_starved ? buf : "",
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 17/23] rcu/context-tracking: Move deferred nocb resched to context tracking

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

To prepare for migrating the RCU eqs accounting code to context tracking,
split the last-resort deferred nocb resched from rcu_user_enter() and
move it into a separate call from context tracking.

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/rcupdate.h  |  6 ++++++
 kernel/context_tracking.c |  8 ++++++++
 kernel/rcu/tree.c         | 15 ++-------------
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index f1562d91c67d2..3717cad983a67 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -112,6 +112,12 @@ static inline void rcu_user_enter(void) { }
 static inline void rcu_user_exit(void) { }
 #endif /* CONFIG_NO_HZ_FULL */
 
+#if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK))
+void rcu_irq_work_resched(void);
+#else
+static inline void rcu_irq_work_resched(void) { }
+#endif
+
 #ifdef CONFIG_RCU_NOCB_CPU
 void rcu_init_nohz(void);
 int rcu_nocb_cpu_offload(int cpu);
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index bf5f498b21d39..8affa0092fab5 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -177,6 +177,8 @@ static __always_inline void context_tracking_recursion_exit(void)
  */
 void noinstr __ct_user_enter(enum ctx_state state)
 {
+	lockdep_assert_irqs_disabled();
+
 	/* Kernel threads aren't supposed to go to userspace */
 	WARN_ON_ONCE(!current->mm);
 
@@ -198,6 +200,12 @@ void noinstr __ct_user_enter(enum ctx_state state)
 				vtime_user_enter(current);
 				instrumentation_end();
 			}
+			/*
+			 * Other than generic entry implementation, we may be past the last
+			 * rescheduling opportunity in the entry code. Trigger a self IPI
+			 * that will fire and reschedule once we resume in user/guest mode.
+			 */
+			rcu_irq_work_resched();
 			rcu_user_enter();
 		}
 		/*
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 006939b29e823..8c0c3490532e3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -681,7 +681,7 @@ static DEFINE_PER_CPU(struct irq_work, late_wakeup_work) =
  * last resort is to fire a local irq_work that will trigger a reschedule once IRQs
  * get re-enabled again.
  */
-noinstr static void rcu_irq_work_resched(void)
+noinstr void rcu_irq_work_resched(void)
 {
 	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 
@@ -697,10 +697,7 @@ noinstr static void rcu_irq_work_resched(void)
 	}
 	instrumentation_end();
 }
-
-#else
-static inline void rcu_irq_work_resched(void) { }
-#endif
+#endif /* #if !defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK) */
 
 /**
  * rcu_user_enter - inform RCU that we are resuming userspace.
@@ -715,14 +712,6 @@ static inline void rcu_irq_work_resched(void) { }
  */
 noinstr void rcu_user_enter(void)
 {
-	lockdep_assert_irqs_disabled();
-
-	/*
-	 * Other than generic entry implementation, we may be past the last
-	 * rescheduling opportunity in the entry code. Trigger a self IPI
-	 * that will fire and reschedule once we resume in user/guest mode.
-	 */
-	rcu_irq_work_resched();
 	rcu_eqs_enter(true);
 }
 
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 18/23] rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Move the core RCU eqs/dynticks functions to context tracking so that
we can later merge all that code within context tracking.

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking.h |  20 ++
 include/linux/rcutree.h          |   3 +
 kernel/context_tracking.c        | 336 +++++++++++++++++++++++++++++++
 kernel/rcu/tree.c                | 324 +----------------------------
 kernel/rcu/tree.h                |   5 -
 kernel/rcu/tree_plugin.h         |  38 +---
 6 files changed, 364 insertions(+), 362 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 01abadb2f9930..1f568676bc1d2 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -122,6 +122,26 @@ static inline void context_tracking_init(void) { }
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 extern void ct_idle_enter(void);
 extern void ct_idle_exit(void);
+
+/*
+ * Is the current CPU in an extended quiescent state?
+ *
+ * No ordering, as we are sampling CPU-local information.
+ */
+static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
+{
+	return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1);
+}
+
+/*
+ * Increment the current CPU's context_tracking structure's ->dynticks field
+ * with ordering.  Return the new value.
+ */
+static __always_inline unsigned long rcu_dynticks_inc(int incby)
+{
+	return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynticks));
+}
+
 #else
 static inline void ct_idle_enter(void) { }
 static inline void ct_idle_exit(void) { }
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 4522b6a7cc42f..24db1e41695c8 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -55,6 +55,9 @@ void rcu_irq_exit_check_preempt(void);
 static inline void rcu_irq_exit_check_preempt(void) { }
 #endif
 
+struct task_struct;
+void rcu_preempt_deferred_qs(struct task_struct *t);
+
 void exit_rcu(void);
 
 void rcu_scheduler_starting(void);
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 8affa0092fab5..f3e92705e0a89 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -21,6 +21,7 @@
 #include <linux/hardirq.h>
 #include <linux/export.h>
 #include <linux/kprobes.h>
+#include <trace/events/rcu.h>
 
 
 DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
@@ -33,6 +34,309 @@ DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
 EXPORT_SYMBOL_GPL(context_tracking);
 
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
+#define TPS(x)  tracepoint_string(x)
+
+/* Record the current task on dyntick-idle entry. */
+static __always_inline void rcu_dynticks_task_enter(void)
+{
+#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
+	WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id());
+#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
+}
+
+/* Record no current task on dyntick-idle exit. */
+static __always_inline void rcu_dynticks_task_exit(void)
+{
+#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
+	WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);
+#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
+}
+
+/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */
+static __always_inline void rcu_dynticks_task_trace_enter(void)
+{
+#ifdef CONFIG_TASKS_TRACE_RCU
+	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
+		current->trc_reader_special.b.need_mb = true;
+#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
+}
+
+/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */
+static __always_inline void rcu_dynticks_task_trace_exit(void)
+{
+#ifdef CONFIG_TASKS_TRACE_RCU
+	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
+		current->trc_reader_special.b.need_mb = false;
+#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
+}
+
+/*
+ * Record entry into an extended quiescent state.  This is only to be
+ * called when not already in an extended quiescent state, that is,
+ * RCU is watching prior to the call to this function and is no longer
+ * watching upon return.
+ */
+static noinstr void rcu_dynticks_eqs_enter(void)
+{
+	int seq;
+
+	/*
+	 * CPUs seeing atomic_add_return() must see prior RCU read-side
+	 * critical sections, and we also must force ordering with the
+	 * next idle sojourn.
+	 */
+	rcu_dynticks_task_trace_enter();  // Before ->dynticks update!
+	seq = rcu_dynticks_inc(1);
+	// RCU is no longer watching.  Better be in extended quiescent state!
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1));
+}
+
+/*
+ * Record exit from an extended quiescent state.  This is only to be
+ * called from an extended quiescent state, that is, RCU is not watching
+ * prior to the call to this function and is watching upon return.
+ */
+static noinstr void rcu_dynticks_eqs_exit(void)
+{
+	int seq;
+
+	/*
+	 * CPUs seeing atomic_add_return() must see prior idle sojourns,
+	 * and we also must force ordering with the next RCU read-side
+	 * critical section.
+	 */
+	seq = rcu_dynticks_inc(1);
+	// RCU is now watching.  Better not be in an extended quiescent state!
+	rcu_dynticks_task_trace_exit();  // After ->dynticks update!
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1));
+}
+
+/*
+ * Enter an RCU extended quiescent state, which can be either the
+ * idle loop or adaptive-tickless usermode execution.
+ *
+ * We crowbar the ->dynticks_nmi_nesting field to zero to allow for
+ * the possibility of usermode upcalls having messed up our count
+ * of interrupt nesting level during the prior busy period.
+ */
+static void noinstr rcu_eqs_enter(bool user)
+{
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
+
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() != DYNTICK_IRQ_NONIDLE);
+	WRITE_ONCE(ct->dynticks_nmi_nesting, 0);
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
+		     ct_dynticks_nesting() == 0);
+	if (ct_dynticks_nesting() != 1) {
+		// RCU will still be watching, so just do accounting and leave.
+		ct->dynticks_nesting--;
+		return;
+	}
+
+	instrumentation_begin();
+	lockdep_assert_irqs_disabled();
+	trace_rcu_dyntick(TPS("Start"), ct_dynticks_nesting(), 0, ct_dynticks());
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
+	rcu_preempt_deferred_qs(current);
+
+	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
+	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+
+	instrumentation_end();
+	WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */
+	// RCU is watching here ...
+	rcu_dynticks_eqs_enter();
+	// ... but is no longer watching here.
+	rcu_dynticks_task_enter();
+}
+
+/*
+ * Exit an RCU extended quiescent state, which can be either the
+ * idle loop or adaptive-tickless usermode execution.
+ *
+ * We crowbar the ->dynticks_nmi_nesting field to DYNTICK_IRQ_NONIDLE to
+ * allow for the possibility of usermode upcalls messing up our count of
+ * interrupt nesting level during the busy period that is just now starting.
+ */
+static void noinstr rcu_eqs_exit(bool user)
+{
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
+	long oldval;
+
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
+	oldval = ct_dynticks_nesting();
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
+	if (oldval) {
+		// RCU was already watching, so just do accounting and leave.
+		ct->dynticks_nesting++;
+		return;
+	}
+	rcu_dynticks_task_exit();
+	// RCU is not watching here ...
+	rcu_dynticks_eqs_exit();
+	// ... but is watching here.
+	instrumentation_begin();
+
+	// instrumentation for the noinstr rcu_dynticks_eqs_exit()
+	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+
+	trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
+	WRITE_ONCE(ct->dynticks_nesting, 1);
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting());
+	WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
+	instrumentation_end();
+}
+
+/**
+ * rcu_nmi_exit - inform RCU of exit from NMI context
+ *
+ * If we are returning from the outermost NMI handler that interrupted an
+ * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting
+ * to let the RCU grace-period handling know that the CPU is back to
+ * being RCU-idle.
+ *
+ * If you add or remove a call to rcu_nmi_exit(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
+ */
+void noinstr rcu_nmi_exit(void)
+{
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
+
+	instrumentation_begin();
+	/*
+	 * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
+	 * (We are exiting an NMI handler, so RCU better be paying attention
+	 * to us!)
+	 */
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() <= 0);
+	WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
+
+	/*
+	 * If the nesting level is not 1, the CPU wasn't RCU-idle, so
+	 * leave it in non-RCU-idle state.
+	 */
+	if (ct_dynticks_nmi_nesting() != 1) {
+		trace_rcu_dyntick(TPS("--="), ct_dynticks_nmi_nesting(), ct_dynticks_nmi_nesting() - 2,
+				  ct_dynticks());
+		WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */
+			   ct_dynticks_nmi_nesting() - 2);
+		instrumentation_end();
+		return;
+	}
+
+	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
+	trace_rcu_dyntick(TPS("Startirq"), ct_dynticks_nmi_nesting(), 0, ct_dynticks());
+	WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
+
+	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
+	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+	instrumentation_end();
+
+	// RCU is watching here ...
+	rcu_dynticks_eqs_enter();
+	// ... but is no longer watching here.
+
+	if (!in_nmi())
+		rcu_dynticks_task_enter();
+}
+
+/**
+ * rcu_nmi_enter - inform RCU of entry to NMI context
+ *
+ * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
+ * ct->dynticks_nmi_nesting to let the RCU grace-period handling know
+ * that the CPU is active.  This implementation permits nested NMIs, as
+ * long as the nesting level does not overflow an int.  (You will probably
+ * run out of stack space first.)
+ *
+ * If you add or remove a call to rcu_nmi_enter(), be sure to test
+ * with CONFIG_RCU_EQS_DEBUG=y.
+ */
+void noinstr rcu_nmi_enter(void)
+{
+	long incby = 2;
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
+
+	/* Complain about underflow. */
+	WARN_ON_ONCE(ct_dynticks_nmi_nesting() < 0);
+
+	/*
+	 * If idle from RCU viewpoint, atomically increment ->dynticks
+	 * to mark non-idle and increment ->dynticks_nmi_nesting by one.
+	 * Otherwise, increment ->dynticks_nmi_nesting by two.  This means
+	 * if ->dynticks_nmi_nesting is equal to one, we are guaranteed
+	 * to be in the outermost NMI handler that interrupted an RCU-idle
+	 * period (observation due to Andy Lutomirski).
+	 */
+	if (rcu_dynticks_curr_cpu_in_eqs()) {
+
+		if (!in_nmi())
+			rcu_dynticks_task_exit();
+
+		// RCU is not watching here ...
+		rcu_dynticks_eqs_exit();
+		// ... but is watching here.
+
+		instrumentation_begin();
+		// instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs()
+		instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks));
+		// instrumentation for the noinstr rcu_dynticks_eqs_exit()
+		instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+
+		incby = 1;
+	} else if (!in_nmi()) {
+		instrumentation_begin();
+		rcu_irq_enter_check_tick();
+	} else  {
+		instrumentation_begin();
+	}
+
+	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
+			  ct_dynticks_nmi_nesting(),
+			  ct_dynticks_nmi_nesting() + incby, ct_dynticks());
+	instrumentation_end();
+	WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */
+		   ct_dynticks_nmi_nesting() + incby);
+	barrier();
+}
+
+/**
+ * rcu_idle_enter - inform RCU that current CPU is entering idle
+ *
+ * Enter idle mode, in other words, -leave- the mode in which RCU
+ * read-side critical sections can occur.  (Though RCU read-side
+ * critical sections can occur in irq handlers in idle, a possibility
+ * handled by irq_enter() and irq_exit().)
+ *
+ * If you add or remove a call to rcu_idle_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
+ */
+void noinstr rcu_idle_enter(void)
+{
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
+	rcu_eqs_enter(false);
+}
+
+/**
+ * rcu_idle_exit - inform RCU that current CPU is leaving idle
+ *
+ * Exit idle mode, in other words, -enter- the mode in which RCU
+ * read-side critical sections can occur.
+ *
+ * If you add or remove a call to rcu_idle_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
+ */
+void noinstr rcu_idle_exit(void)
+{
+	unsigned long flags;
+
+	raw_local_irq_save(flags);
+	rcu_eqs_exit(false);
+	raw_local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(rcu_idle_exit);
+
 noinstr void ct_idle_enter(void)
 {
 	rcu_idle_enter();
@@ -139,6 +443,38 @@ noinstr void ct_nmi_exit(void)
 }
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
+#ifdef CONFIG_NO_HZ_FULL
+/**
+ * rcu_user_enter - inform RCU that we are resuming userspace.
+ *
+ * Enter RCU idle mode right before resuming userspace.  No use of RCU
+ * is permitted between this call and rcu_user_exit(). This way the
+ * CPU doesn't need to maintain the tick for RCU maintenance purposes
+ * when the CPU runs in userspace.
+ *
+ * If you add or remove a call to rcu_user_enter(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
+ */
+noinstr void rcu_user_enter(void)
+{
+	rcu_eqs_enter(true);
+}
+
+/**
+ * rcu_user_exit - inform RCU that we are exiting userspace.
+ *
+ * Exit RCU idle mode while entering the kernel because it can
+ * run a RCU read side critical section anytime.
+ *
+ * If you add or remove a call to rcu_user_exit(), be sure to test with
+ * CONFIG_RCU_EQS_DEBUG=y.
+ */
+void noinstr rcu_user_exit(void)
+{
+	rcu_eqs_exit(true);
+}
+#endif /* #ifdef CONFIG_NO_HZ_FULL */
+
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 
 #define CREATE_TRACE_POINTS
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8c0c3490532e3..e2a2083079a2c 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -62,6 +62,7 @@
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/kasan.h>
+#include <linux/context_tracking.h>
 #include "../time/tick-internal.h"
 
 #include "tree.h"
@@ -259,56 +260,6 @@ void rcu_softirq_qs(void)
 	rcu_tasks_qs(current, false);
 }
 
-/*
- * Increment the current CPU's rcu_data structure's ->dynticks field
- * with ordering.  Return the new value.
- */
-static noinline noinstr unsigned long rcu_dynticks_inc(int incby)
-{
-	return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynticks));
-}
-
-/*
- * Record entry into an extended quiescent state.  This is only to be
- * called when not already in an extended quiescent state, that is,
- * RCU is watching prior to the call to this function and is no longer
- * watching upon return.
- */
-static noinstr void rcu_dynticks_eqs_enter(void)
-{
-	int seq;
-
-	/*
-	 * CPUs seeing atomic_add_return() must see prior RCU read-side
-	 * critical sections, and we also must force ordering with the
-	 * next idle sojourn.
-	 */
-	rcu_dynticks_task_trace_enter();  // Before ->dynticks update!
-	seq = rcu_dynticks_inc(1);
-	// RCU is no longer watching.  Better be in extended quiescent state!
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1));
-}
-
-/*
- * Record exit from an extended quiescent state.  This is only to be
- * called from an extended quiescent state, that is, RCU is not watching
- * prior to the call to this function and is watching upon return.
- */
-static noinstr void rcu_dynticks_eqs_exit(void)
-{
-	int seq;
-
-	/*
-	 * CPUs seeing atomic_add_return() must see prior idle sojourns,
-	 * and we also must force ordering with the next RCU read-side
-	 * critical section.
-	 */
-	seq = rcu_dynticks_inc(1);
-	// RCU is now watching.  Better not be in an extended quiescent state!
-	rcu_dynticks_task_trace_exit();  // After ->dynticks update!
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1));
-}
-
 /*
  * Reset the current CPU's ->dynticks counter to indicate that the
  * newly onlined CPU is no longer in an extended quiescent state.
@@ -326,16 +277,6 @@ static void rcu_dynticks_eqs_online(void)
 	rcu_dynticks_inc(1);
 }
 
-/*
- * Is the current CPU in an extended quiescent state?
- *
- * No ordering, as we are sampling CPU-local information.
- */
-static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
-{
-	return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1);
-}
-
 /*
  * Snapshot the ->dynticks counter with full ordering so as to allow
  * stable comparison of this counter with past and future snapshots.
@@ -601,65 +542,7 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
 }
 EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
 
-/*
- * Enter an RCU extended quiescent state, which can be either the
- * idle loop or adaptive-tickless usermode execution.
- *
- * We crowbar the ->dynticks_nmi_nesting field to zero to allow for
- * the possibility of usermode upcalls having messed up our count
- * of interrupt nesting level during the prior busy period.
- */
-static noinstr void rcu_eqs_enter(bool user)
-{
-	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-
-	WARN_ON_ONCE(ct_dynticks_nmi_nesting() != DYNTICK_IRQ_NONIDLE);
-	WRITE_ONCE(ct->dynticks_nmi_nesting, 0);
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-		     ct_dynticks_nesting() == 0);
-	if (ct_dynticks_nesting() != 1) {
-		// RCU will still be watching, so just do accounting and leave.
-		ct->dynticks_nesting--;
-		return;
-	}
-
-	instrumentation_begin();
-	lockdep_assert_irqs_disabled();
-	trace_rcu_dyntick(TPS("Start"), ct_dynticks_nesting(), 0, ct_dynticks());
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
-	rcu_preempt_deferred_qs(current);
-
-	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
-	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
-
-	instrumentation_end();
-	WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */
-	// RCU is watching here ...
-	rcu_dynticks_eqs_enter();
-	// ... but is no longer watching here.
-	rcu_dynticks_task_enter();
-}
-
-/**
- * rcu_idle_enter - inform RCU that current CPU is entering idle
- *
- * Enter idle mode, in other words, -leave- the mode in which RCU
- * read-side critical sections can occur.  (Though RCU read-side
- * critical sections can occur in irq handlers in idle, a possibility
- * handled by irq_enter() and irq_exit().)
- *
- * If you add or remove a call to rcu_idle_enter(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-void noinstr rcu_idle_enter(void)
-{
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
-	rcu_eqs_enter(false);
-}
-
-#ifdef CONFIG_NO_HZ_FULL
-
-#if !defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK)
+#if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK))
 /*
  * An empty function that will trigger a reschedule on
  * IRQ tail once IRQs get re-enabled on userspace/guest resume.
@@ -697,78 +580,7 @@ noinstr void rcu_irq_work_resched(void)
 	}
 	instrumentation_end();
 }
-#endif /* #if !defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK) */
-
-/**
- * rcu_user_enter - inform RCU that we are resuming userspace.
- *
- * Enter RCU idle mode right before resuming userspace.  No use of RCU
- * is permitted between this call and rcu_user_exit(). This way the
- * CPU doesn't need to maintain the tick for RCU maintenance purposes
- * when the CPU runs in userspace.
- *
- * If you add or remove a call to rcu_user_enter(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-noinstr void rcu_user_enter(void)
-{
-	rcu_eqs_enter(true);
-}
-
-#endif /* CONFIG_NO_HZ_FULL */
-
-/**
- * rcu_nmi_exit - inform RCU of exit from NMI context
- *
- * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting
- * to let the RCU grace-period handling know that the CPU is back to
- * being RCU-idle.
- *
- * If you add or remove a call to rcu_nmi_exit(), be sure to test
- * with CONFIG_RCU_EQS_DEBUG=y.
- */
-noinstr void rcu_nmi_exit(void)
-{
-	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-
-	instrumentation_begin();
-	/*
-	 * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
-	 * (We are exiting an NMI handler, so RCU better be paying attention
-	 * to us!)
-	 */
-	WARN_ON_ONCE(ct_dynticks_nmi_nesting() <= 0);
-	WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
-
-	/*
-	 * If the nesting level is not 1, the CPU wasn't RCU-idle, so
-	 * leave it in non-RCU-idle state.
-	 */
-	if (ct_dynticks_nmi_nesting() != 1) {
-		trace_rcu_dyntick(TPS("--="), ct_dynticks_nmi_nesting(), ct_dynticks_nmi_nesting() - 2,
-				  ct_dynticks());
-		WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */
-			   ct_dynticks_nmi_nesting() - 2);
-		instrumentation_end();
-		return;
-	}
-
-	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-	trace_rcu_dyntick(TPS("Startirq"), ct_dynticks_nmi_nesting(), 0, ct_dynticks());
-	WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
-
-	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
-	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
-	instrumentation_end();
-
-	// RCU is watching here ...
-	rcu_dynticks_eqs_enter();
-	// ... but is no longer watching here.
-
-	if (!in_nmi())
-		rcu_dynticks_task_enter();
-}
+#endif /* #if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK)) */
 
 #ifdef CONFIG_PROVE_RCU
 /**
@@ -788,77 +600,7 @@ void rcu_irq_exit_check_preempt(void)
 }
 #endif /* #ifdef CONFIG_PROVE_RCU */
 
-/*
- * Exit an RCU extended quiescent state, which can be either the
- * idle loop or adaptive-tickless usermode execution.
- *
- * We crowbar the ->dynticks_nmi_nesting field to DYNTICK_IRQ_NONIDLE to
- * allow for the possibility of usermode upcalls messing up our count of
- * interrupt nesting level during the busy period that is just now starting.
- */
-static void noinstr rcu_eqs_exit(bool user)
-{
-	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-	long oldval;
-
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
-	oldval = ct_dynticks_nesting();
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
-	if (oldval) {
-		// RCU was already watching, so just do accounting and leave.
-		ct->dynticks_nesting++;
-		return;
-	}
-	rcu_dynticks_task_exit();
-	// RCU is not watching here ...
-	rcu_dynticks_eqs_exit();
-	// ... but is watching here.
-	instrumentation_begin();
-
-	// instrumentation for the noinstr rcu_dynticks_eqs_exit()
-	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
-
-	trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
-	WRITE_ONCE(ct->dynticks_nesting, 1);
-	WARN_ON_ONCE(ct_dynticks_nmi_nesting());
-	WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
-	instrumentation_end();
-}
-
-/**
- * rcu_idle_exit - inform RCU that current CPU is leaving idle
- *
- * Exit idle mode, in other words, -enter- the mode in which RCU
- * read-side critical sections can occur.
- *
- * If you add or remove a call to rcu_idle_exit(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-void noinstr rcu_idle_exit(void)
-{
-	unsigned long flags;
-
-	raw_local_irq_save(flags);
-	rcu_eqs_exit(false);
-	raw_local_irq_restore(flags);
-}
-
 #ifdef CONFIG_NO_HZ_FULL
-/**
- * rcu_user_exit - inform RCU that we are exiting userspace.
- *
- * Exit RCU idle mode while entering the kernel because it can
- * run a RCU read side critical section anytime.
- *
- * If you add or remove a call to rcu_user_exit(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-void noinstr rcu_user_exit(void)
-{
-	rcu_eqs_exit(true);
-}
-
 /**
  * __rcu_irq_enter_check_tick - Enable scheduler tick on CPU if RCU needs it.
  *
@@ -921,66 +663,6 @@ void __rcu_irq_enter_check_tick(void)
 }
 #endif /* CONFIG_NO_HZ_FULL */
 
-/**
- * rcu_nmi_enter - inform RCU of entry to NMI context
- *
- * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
- * ct->dynticks_nmi_nesting to let the RCU grace-period handling know
- * that the CPU is active.  This implementation permits nested NMIs, as
- * long as the nesting level does not overflow an int.  (You will probably
- * run out of stack space first.)
- *
- * If you add or remove a call to rcu_nmi_enter(), be sure to test
- * with CONFIG_RCU_EQS_DEBUG=y.
- */
-noinstr void rcu_nmi_enter(void)
-{
-	long incby = 2;
-	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
-
-	/* Complain about underflow. */
-	WARN_ON_ONCE(ct_dynticks_nmi_nesting() < 0);
-
-	/*
-	 * If idle from RCU viewpoint, atomically increment ->dynticks
-	 * to mark non-idle and increment ->dynticks_nmi_nesting by one.
-	 * Otherwise, increment ->dynticks_nmi_nesting by two.  This means
-	 * if ->dynticks_nmi_nesting is equal to one, we are guaranteed
-	 * to be in the outermost NMI handler that interrupted an RCU-idle
-	 * period (observation due to Andy Lutomirski).
-	 */
-	if (rcu_dynticks_curr_cpu_in_eqs()) {
-
-		if (!in_nmi())
-			rcu_dynticks_task_exit();
-
-		// RCU is not watching here ...
-		rcu_dynticks_eqs_exit();
-		// ... but is watching here.
-
-		instrumentation_begin();
-		// instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs()
-		instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks));
-		// instrumentation for the noinstr rcu_dynticks_eqs_exit()
-		instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
-
-		incby = 1;
-	} else if (!in_nmi()) {
-		instrumentation_begin();
-		rcu_irq_enter_check_tick();
-	} else  {
-		instrumentation_begin();
-	}
-
-	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
-			  ct_dynticks_nmi_nesting(),
-			  ct_dynticks_nmi_nesting() + incby, ct_dynticks());
-	instrumentation_end();
-	WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */
-		   ct_dynticks_nmi_nesting() + incby);
-	barrier();
-}
-
 /*
  * Check to see if any future non-offloaded RCU-related work will need
  * to be done by the current CPU, even if none need be done immediately,
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 72dbf8512ce78..0d5d1de327e41 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -427,7 +427,6 @@ static void rcu_cpu_kthread_setup(unsigned int cpu);
 static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp);
 static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
 static bool rcu_preempt_need_deferred_qs(struct task_struct *t);
-static void rcu_preempt_deferred_qs(struct task_struct *t);
 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
 static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp);
 static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq);
@@ -467,10 +466,6 @@ do {								\
 
 static void rcu_bind_gp_kthread(void);
 static bool rcu_nohz_full_cpu(void);
-static void rcu_dynticks_task_enter(void);
-static void rcu_dynticks_task_exit(void);
-static void rcu_dynticks_task_trace_enter(void);
-static void rcu_dynticks_task_trace_exit(void);
 
 /* Forward declarations for tree_stall.h */
 static void record_gp_stall_check_time(void);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index c8ba0fe17267c..c8c57e1a5dfd3 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -595,7 +595,7 @@ static bool rcu_preempt_need_deferred_qs(struct task_struct *t)
  * evaluate safety in terms of interrupt, softirq, and preemption
  * disabling.
  */
-static void rcu_preempt_deferred_qs(struct task_struct *t)
+notrace void rcu_preempt_deferred_qs(struct task_struct *t)
 {
 	unsigned long flags;
 
@@ -935,7 +935,7 @@ static bool rcu_preempt_need_deferred_qs(struct task_struct *t)
 // period for a quiescent state from this CPU.  Note that requests from
 // tasks are handled when removing the task from the blocked-tasks list
 // below.
-static void rcu_preempt_deferred_qs(struct task_struct *t)
+void rcu_preempt_deferred_qs(struct task_struct *t)
 {
 	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 
@@ -1290,37 +1290,3 @@ static void rcu_bind_gp_kthread(void)
 		return;
 	housekeeping_affine(current, HK_TYPE_RCU);
 }
-
-/* Record the current task on dyntick-idle entry. */
-static __always_inline void rcu_dynticks_task_enter(void)
-{
-#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
-	WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id());
-#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
-}
-
-/* Record no current task on dyntick-idle exit. */
-static __always_inline void rcu_dynticks_task_exit(void)
-{
-#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
-	WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);
-#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
-}
-
-/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */
-static __always_inline void rcu_dynticks_task_trace_enter(void)
-{
-#ifdef CONFIG_TASKS_TRACE_RCU
-	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
-		current->trc_reader_special.b.need_mb = true;
-#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
-}
-
-/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */
-static __always_inline void rcu_dynticks_task_trace_exit(void)
-{
-#ifdef CONFIG_TASKS_TRACE_RCU
-	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))
-		current->trc_reader_special.b.need_mb = false;
-#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
-}
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 19/23] rcu/context-tracking: Remove unused and/or unecessary middle functions

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Some eqs functions are now only used internally by context tracking, so
their public declarations can be removed.

Also middle functions such as rcu_user_*() and rcu_idle_*()
which now directly call to rcu_eqs_enter() and rcu_eqs_exit() can be
wiped out as well.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 Documentation/RCU/stallwarn.rst |  2 +-
 include/linux/hardirq.h         |  8 ---
 include/linux/rcupdate.h        |  8 ---
 include/linux/rcutiny.h         |  2 -
 include/linux/rcutree.h         |  2 -
 kernel/context_tracking.c       | 98 +++++++++------------------------
 6 files changed, 28 insertions(+), 92 deletions(-)

diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst
index ce1f58a9d954b..e38c587067fc8 100644
--- a/Documentation/RCU/stallwarn.rst
+++ b/Documentation/RCU/stallwarn.rst
@@ -97,7 +97,7 @@ warnings:
 	which will include additional debugging information.
 
 -	A low-level kernel issue that either fails to invoke one of the
-	variants of rcu_user_enter(), rcu_user_exit(), ct_idle_enter(),
+	variants of rcu_eqs_enter(true), rcu_eqs_exit(true), ct_idle_enter(),
 	ct_idle_exit(), ct_irq_enter(), or ct_irq_exit() on the one
 	hand, or that invokes one of them too many times on the other.
 	Historically, the most frequent issue has been an omission
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 345cdbe9c1b70..d57cab4d4c06f 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -92,14 +92,6 @@ void irq_exit_rcu(void);
 #define arch_nmi_exit()		do { } while (0)
 #endif
 
-#ifdef CONFIG_TINY_RCU
-static inline void rcu_nmi_enter(void) { }
-static inline void rcu_nmi_exit(void) { }
-#else
-extern void rcu_nmi_enter(void);
-extern void rcu_nmi_exit(void);
-#endif
-
 /*
  * NMI vs Tracing
  * --------------
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 3717cad983a67..434da1eb88cd9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -104,14 +104,6 @@ static inline void rcu_sysrq_start(void) { }
 static inline void rcu_sysrq_end(void) { }
 #endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */
 
-#ifdef CONFIG_NO_HZ_FULL
-void rcu_user_enter(void);
-void rcu_user_exit(void);
-#else
-static inline void rcu_user_enter(void) { }
-static inline void rcu_user_exit(void) { }
-#endif /* CONFIG_NO_HZ_FULL */
-
 #if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK))
 void rcu_irq_work_resched(void);
 #else
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 591119413cf1d..900ba35c3582d 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -76,8 +76,6 @@ static inline int rcu_needs_cpu(void)
 static inline void rcu_virt_note_context_switch(int cpu) { }
 static inline void rcu_cpu_stall_reset(void) { }
 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
-static inline void rcu_idle_enter(void) { }
-static inline void rcu_idle_exit(void) { }
 static inline void rcu_irq_exit_check_preempt(void) { }
 #define rcu_is_idle_cpu(cpu) \
 	(is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq())
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 24db1e41695c8..9cca00ed9bc9f 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -45,8 +45,6 @@ unsigned long start_poll_synchronize_rcu(void);
 bool poll_state_synchronize_rcu(unsigned long oldstate);
 void cond_synchronize_rcu(unsigned long oldstate);
 
-void rcu_idle_enter(void);
-void rcu_idle_exit(void);
 bool rcu_is_idle_cpu(int cpu);
 
 #ifdef CONFIG_PROVE_RCU
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index f3e92705e0a89..8b0979412f755 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -189,17 +189,17 @@ static void noinstr rcu_eqs_exit(bool user)
 }
 
 /**
- * rcu_nmi_exit - inform RCU of exit from NMI context
+ * ct_nmi_exit - inform RCU of exit from NMI context
  *
  * If we are returning from the outermost NMI handler that interrupted an
  * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
- * If you add or remove a call to rcu_nmi_exit(), be sure to test
+ * If you add or remove a call to ct_nmi_exit(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
  */
-void noinstr rcu_nmi_exit(void)
+void noinstr ct_nmi_exit(void)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
@@ -242,7 +242,7 @@ void noinstr rcu_nmi_exit(void)
 }
 
 /**
- * rcu_nmi_enter - inform RCU of entry to NMI context
+ * ct_nmi_enter - inform RCU of entry to NMI context
  *
  * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
  * ct->dynticks_nmi_nesting to let the RCU grace-period handling know
@@ -250,10 +250,10 @@ void noinstr rcu_nmi_exit(void)
  * long as the nesting level does not overflow an int.  (You will probably
  * run out of stack space first.)
  *
- * If you add or remove a call to rcu_nmi_enter(), be sure to test
+ * If you add or remove a call to ct_nmi_enter(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
  */
-void noinstr rcu_nmi_enter(void)
+void noinstr ct_nmi_enter(void)
 {
 	long incby = 2;
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
@@ -302,32 +302,33 @@ void noinstr rcu_nmi_enter(void)
 }
 
 /**
- * rcu_idle_enter - inform RCU that current CPU is entering idle
+ * ct_idle_enter - inform RCU that current CPU is entering idle
  *
  * Enter idle mode, in other words, -leave- the mode in which RCU
  * read-side critical sections can occur.  (Though RCU read-side
  * critical sections can occur in irq handlers in idle, a possibility
  * handled by irq_enter() and irq_exit().)
  *
- * If you add or remove a call to rcu_idle_enter(), be sure to test with
+ * If you add or remove a call to ct_idle_enter(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void noinstr rcu_idle_enter(void)
+void noinstr ct_idle_enter(void)
 {
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
 	rcu_eqs_enter(false);
 }
+EXPORT_SYMBOL_GPL(ct_idle_enter);
 
 /**
- * rcu_idle_exit - inform RCU that current CPU is leaving idle
+ * ct_idle_exit - inform RCU that current CPU is leaving idle
  *
  * Exit idle mode, in other words, -enter- the mode in which RCU
  * read-side critical sections can occur.
  *
- * If you add or remove a call to rcu_idle_exit(), be sure to test with
+ * If you add or remove a call to ct_idle_exit(), be sure to test with
  * CONFIG_RCU_EQS_DEBUG=y.
  */
-void noinstr rcu_idle_exit(void)
+void noinstr ct_idle_exit(void)
 {
 	unsigned long flags;
 
@@ -335,18 +336,6 @@ void noinstr rcu_idle_exit(void)
 	rcu_eqs_exit(false);
 	raw_local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(rcu_idle_exit);
-
-noinstr void ct_idle_enter(void)
-{
-	rcu_idle_enter();
-}
-EXPORT_SYMBOL_GPL(ct_idle_enter);
-
-void ct_idle_exit(void)
-{
-	rcu_idle_exit();
-}
 EXPORT_SYMBOL_GPL(ct_idle_exit);
 
 /**
@@ -431,50 +420,11 @@ void ct_irq_exit_irqson(void)
 	ct_irq_exit();
 	local_irq_restore(flags);
 }
-
-noinstr void ct_nmi_enter(void)
-{
-	rcu_nmi_enter();
-}
-
-noinstr void ct_nmi_exit(void)
-{
-	rcu_nmi_exit();
-}
+#else
+static __always_inline void rcu_eqs_enter(bool user) { }
+static __always_inline void rcu_eqs_exit(bool user) { }
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
-#ifdef CONFIG_NO_HZ_FULL
-/**
- * rcu_user_enter - inform RCU that we are resuming userspace.
- *
- * Enter RCU idle mode right before resuming userspace.  No use of RCU
- * is permitted between this call and rcu_user_exit(). This way the
- * CPU doesn't need to maintain the tick for RCU maintenance purposes
- * when the CPU runs in userspace.
- *
- * If you add or remove a call to rcu_user_enter(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-noinstr void rcu_user_enter(void)
-{
-	rcu_eqs_enter(true);
-}
-
-/**
- * rcu_user_exit - inform RCU that we are exiting userspace.
- *
- * Exit RCU idle mode while entering the kernel because it can
- * run a RCU read side critical section anytime.
- *
- * If you add or remove a call to rcu_user_exit(), be sure to test with
- * CONFIG_RCU_EQS_DEBUG=y.
- */
-void noinstr rcu_user_exit(void)
-{
-	rcu_eqs_exit(true);
-}
-#endif /* #ifdef CONFIG_NO_HZ_FULL */
-
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 
 #define CREATE_TRACE_POINTS
@@ -542,7 +492,13 @@ void noinstr __ct_user_enter(enum ctx_state state)
 			 * that will fire and reschedule once we resume in user/guest mode.
 			 */
 			rcu_irq_work_resched();
-			rcu_user_enter();
+			/*
+			 * Enter RCU idle mode right before resuming userspace.  No use of RCU
+			 * is permitted between this call and rcu_eqs_exit(). This way the
+			 * CPU doesn't need to maintain the tick for RCU maintenance purposes
+			 * when the CPU runs in userspace.
+			 */
+			rcu_eqs_enter(true);
 		}
 		/*
 		 * Even if context tracking is disabled on this CPU, because it's outside
@@ -579,7 +535,7 @@ void ct_user_enter(enum ctx_state state)
 	/*
 	 * Some contexts may involve an exception occuring in an irq,
 	 * leading to that nesting:
-	 * ct_irq_enter() rcu_user_exit() rcu_user_exit() ct_irq_exit()
+	 * ct_irq_enter() rcu_eqs_exit(true) rcu_eqs_enter(true) ct_irq_exit()
 	 * This would mess up the dyntick_nesting count though. And rcu_irq_*()
 	 * helpers are enough to protect RCU uses inside the exception. So
 	 * just return immediately if we detect we are in an IRQ.
@@ -631,10 +587,10 @@ void noinstr __ct_user_exit(enum ctx_state state)
 	if (__this_cpu_read(context_tracking.state) == state) {
 		if (__this_cpu_read(context_tracking.active)) {
 			/*
-			 * We are going to run code that may use RCU. Inform
-			 * RCU core about that (ie: we may need the tick again).
+			 * Exit RCU idle mode while entering the kernel because it can
+			 * run a RCU read side critical section anytime.
 			 */
-			rcu_user_exit();
+			rcu_eqs_exit(true);
 			if (state == CONTEXT_USER) {
 				instrumentation_begin();
 				vtime_user_exit(current);
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 20/23] context_tracking: Convert state to atomic_t

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Context tracking's state and dynticks counter are going to be merged
in a single field so that both updates can happen atomically and at the
same time. Prepare for that with converting the state into an atomic_t.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking.h       | 24 +++++-------------
 include/linux/context_tracking_state.h | 34 +++++++++++++++++++++++---
 kernel/context_tracking.c              | 15 +++++++-----
 3 files changed, 45 insertions(+), 28 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 1f568676bc1d2..a8c1db0a3f65a 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -56,7 +56,7 @@ static inline enum ctx_state exception_enter(void)
 	    !context_tracking_enabled())
 		return 0;
 
-	prev_ctx = this_cpu_read(context_tracking.state);
+	prev_ctx = __ct_state();
 	if (prev_ctx != CONTEXT_KERNEL)
 		ct_user_exit(prev_ctx);
 
@@ -86,33 +86,21 @@ static __always_inline void context_tracking_guest_exit(void)
 		__ct_user_exit(CONTEXT_GUEST);
 }
 
-/**
- * ct_state() - return the current context tracking state if known
- *
- * Returns the current cpu's context tracking state if context tracking
- * is enabled.  If context tracking is disabled, returns
- * CONTEXT_DISABLED.  This should be used primarily for debugging.
- */
-static __always_inline enum ctx_state ct_state(void)
-{
-	return context_tracking_enabled() ?
-		this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
-}
+#define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
+
 #else
 static inline void user_enter(void) { }
 static inline void user_exit(void) { }
 static inline void user_enter_irqoff(void) { }
 static inline void user_exit_irqoff(void) { }
-static inline enum ctx_state exception_enter(void) { return 0; }
+static inline int exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
-static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
+static inline int ct_state(void) { return -1; }
 static __always_inline bool context_tracking_guest_enter(void) { return false; }
 static inline void context_tracking_guest_exit(void) { }
-
+#define CT_WARN_ON(cond)
 #endif /* !CONFIG_CONTEXT_TRACKING_USER */
 
-#define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
-
 #ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE
 extern void context_tracking_init(void);
 #else
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 2f957b48e24f9..7d2dddf0da690 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -6,6 +6,9 @@
 #include <linux/static_key.h>
 #include <linux/context_tracking_irq.h>
 
+/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
+#define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
+
 enum ctx_state {
 	CONTEXT_DISABLED = -1,	/* returned by ct_state() if unknown */
 	CONTEXT_KERNEL = 0,
@@ -13,9 +16,6 @@ enum ctx_state {
 	CONTEXT_GUEST,
 };
 
-/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
-#define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
-
 struct context_tracking {
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 	/*
@@ -26,7 +26,7 @@ struct context_tracking {
 	 */
 	bool active;
 	int recursion;
-	enum ctx_state state;
+	atomic_t state;
 #endif
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	atomic_t dynticks;		/* Even value for idle, else odd. */
@@ -98,6 +98,32 @@ static inline bool context_tracking_enabled_this_cpu(void)
 	return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
 }
 
+static __always_inline int __ct_state(void)
+{
+	return atomic_read(this_cpu_ptr(&context_tracking.state));
+}
+
+/**
+ * ct_state() - return the current context tracking state if known
+ *
+ * Returns the current cpu's context tracking state if context tracking
+ * is enabled.  If context tracking is disabled, returns
+ * CONTEXT_DISABLED.  This should be used primarily for debugging.
+ */
+static __always_inline int ct_state(void)
+{
+	int ret;
+
+	if (!context_tracking_enabled())
+		return CONTEXT_DISABLED;
+
+	preempt_disable();
+	ret = __ct_state();
+	preempt_enable();
+
+	return ret;
+}
+
 #else
 static __always_inline bool context_tracking_enabled(void) { return false; }
 static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 8b0979412f755..c477c7d696e0f 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -463,6 +463,7 @@ static __always_inline void context_tracking_recursion_exit(void)
  */
 void noinstr __ct_user_enter(enum ctx_state state)
 {
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 	lockdep_assert_irqs_disabled();
 
 	/* Kernel threads aren't supposed to go to userspace */
@@ -471,8 +472,8 @@ void noinstr __ct_user_enter(enum ctx_state state)
 	if (!context_tracking_recursion_enter())
 		return;
 
-	if ( __this_cpu_read(context_tracking.state) != state) {
-		if (__this_cpu_read(context_tracking.active)) {
+	if (__ct_state() != state) {
+		if (ct->active) {
 			/*
 			 * At this stage, only low level arch entry code remains and
 			 * then we'll run in userspace. We can assume there won't be
@@ -513,7 +514,7 @@ void noinstr __ct_user_enter(enum ctx_state state)
 		 * OTOH we can spare the calls to vtime and RCU when context_tracking.active
 		 * is false because we know that CPU is not tickless.
 		 */
-		__this_cpu_write(context_tracking.state, state);
+		atomic_set(&ct->state, state);
 	}
 	context_tracking_recursion_exit();
 }
@@ -581,11 +582,13 @@ NOKPROBE_SYMBOL(user_enter_callable);
  */
 void noinstr __ct_user_exit(enum ctx_state state)
 {
+	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
+
 	if (!context_tracking_recursion_enter())
 		return;
 
-	if (__this_cpu_read(context_tracking.state) == state) {
-		if (__this_cpu_read(context_tracking.active)) {
+	if (__ct_state() == state) {
+		if (ct->active) {
 			/*
 			 * Exit RCU idle mode while entering the kernel because it can
 			 * run a RCU read side critical section anytime.
@@ -598,7 +601,7 @@ void noinstr __ct_user_exit(enum ctx_state state)
 				instrumentation_end();
 			}
 		}
-		__this_cpu_write(context_tracking.state, CONTEXT_KERNEL);
+		atomic_set(&ct->state, CONTEXT_KERNEL);
 	}
 	context_tracking_recursion_exit();
 }
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 0/23] RCU/context-tracking updates for v5.20

[Paul E. McKenney]

Hello!

This series merges RCU's dyntick-idle tracking into context tracking,
thus reducing the overhead of transitioning to kernel mode from either
idle or nohz_full userspace execution for kernels that track context
independently of RCU.  (Primarily for NO_HZ_FULL kernels.)

1.	Dump rcuc kthread status for CPUs not reporting quiescent state,
	courtesy of Zqiang.

2.	Apply noinstr to rcu_idle_enter() and rcu_idle_exit().

3.	context_tracking: Remove unused context_tracking_in_user(),
	courtesy of Frederic Weisbecker.

4.	context_tracking: Add a note about noinstr VS unsafe context
	tracking functions, courtesy of Frederic Weisbecker.

5.	context_tracking: Rename __context_tracking_enter/exit() to
	__ct_user_enter/exit(), courtesy of Frederic Weisbecker.

6.	context_tracking: Rename context_tracking_user_enter/exit()
	to user_enter/exit_callable(), courtesy of Frederic Weisbecker.

7.	context_tracking: Rename context_tracking_enter/exit() to
	ct_user_enter/exit(), courtesy of Frederic Weisbecker.

8.	context_tracking: Rename context_tracking_cpu_set() to
	ct_cpu_track_user(), courtesy of Frederic Weisbecker.

9.	context_tracking: Split user tracking Kconfig, courtesy of
	Frederic Weisbecker.

10.	context_tracking: Take idle eqs entrypoints over RCU, courtesy
	of Frederic Weisbecker.

11.	context_tracking: Take IRQ eqs entrypoints over RCU, courtesy
	of Frederic Weisbecker.

12.	context_tracking: Take NMI eqs entrypoints over RCU, courtesy
	of Frederic Weisbecker.

13.	rcu/context-tracking: Remove rcu_irq_enter/exit(), courtesy of
	Frederic Weisbecker.

14.	rcu/context_tracking: Move dynticks counter to context tracking,
	courtesy of Frederic Weisbecker.

15.	rcu/context_tracking: Move dynticks_nesting to context tracking,
	courtesy of Frederic Weisbecker.

16.	rcu/context_tracking: Move dynticks_nmi_nesting to context
	tracking, courtesy of Frederic Weisbecker.

17.	rcu/context-tracking: Move deferred nocb resched to context
	tracking, courtesy of Frederic Weisbecker.

18.	rcu/context-tracking: Move RCU-dynticks internal functions to
	context_tracking, courtesy of Frederic Weisbecker.

19.	rcu/context-tracking: Remove unused and/or unecessary middle
	functions, courtesy of Frederic Weisbecker.

20.	context_tracking: Convert state to atomic_t, courtesy of Frederic
	Weisbecker.

21.	rcu/context_tracking: Merge dynticks counter and context tracking
	states, courtesy of Frederic Weisbecker.

22.	MAINTAINERS: Add Paul as context tracking maintainer, courtesy
	of Frederic Weisbecker.

23.	context_tracking: Interrupts always disabled for ct_idle_exit(),
	courtesy of Peter Zijlstra.

						Thanx, Paul

------------------------------------------------------------------------

 Documentation/RCU/Design/Requirements/Requirements.rst          |    2 
 Documentation/RCU/stallwarn.rst                                 |    6 
 arch/Kconfig                                                    |    4 
 arch/arm/kernel/entry-header.S                                  |    4 
 arch/arm64/kernel/entry-common.c                                |    8 
 arch/csky/kernel/entry.S                                        |    4 
 arch/riscv/kernel/entry.S                                       |    6 
 b/Documentation/RCU/Design/Requirements/Requirements.rst        |   10 
 b/Documentation/RCU/stallwarn.rst                               |    4 
 b/Documentation/features/time/context-tracking/arch-support.txt |    6 
 b/MAINTAINERS                                                   |    1 
 b/arch/Kconfig                                                  |    4 
 b/arch/arm/Kconfig                                              |    2 
 b/arch/arm/kernel/entry-common.S                                |    4 
 b/arch/arm/kernel/entry-header.S                                |    8 
 b/arch/arm/mach-imx/cpuidle-imx6q.c                             |    5 
 b/arch/arm64/Kconfig                                            |    2 
 b/arch/arm64/kernel/entry-common.c                              |    6 
 b/arch/csky/Kconfig                                             |    2 
 b/arch/csky/kernel/entry.S                                      |    4 
 b/arch/mips/Kconfig                                             |    2 
 b/arch/powerpc/Kconfig                                          |    2 
 b/arch/powerpc/include/asm/context_tracking.h                   |    2 
 b/arch/riscv/Kconfig                                            |    2 
 b/arch/riscv/kernel/entry.S                                     |    6 
 b/arch/sparc/Kconfig                                            |    2 
 b/arch/sparc/kernel/rtrap_64.S                                  |    2 
 b/arch/x86/Kconfig                                              |    4 
 b/arch/x86/mm/fault.c                                           |    2 
 b/drivers/acpi/processor_idle.c                                 |    5 
 b/drivers/cpuidle/cpuidle-psci.c                                |    8 
 b/drivers/cpuidle/cpuidle-riscv-sbi.c                           |    8 
 b/drivers/cpuidle/cpuidle.c                                     |    9 
 b/include/linux/context_tracking.h                              |   12 
 b/include/linux/context_tracking_irq.h                          |   17 
 b/include/linux/context_tracking_state.h                        |    5 
 b/include/linux/entry-common.h                                  |   10 
 b/include/linux/hardirq.h                                       |    4 
 b/include/linux/rcupdate.h                                      |    2 
 b/include/linux/rcutiny.h                                       |    4 
 b/include/linux/rcutree.h                                       |    4 
 b/include/linux/tracepoint.h                                    |    4 
 b/init/Kconfig                                                  |    4 
 b/kernel/cfi.c                                                  |    4 
 b/kernel/context_tracking.c                                     |   34 
 b/kernel/cpu_pm.c                                               |    8 
 b/kernel/entry/common.c                                         |   12 
 b/kernel/extable.c                                              |    4 
 b/kernel/locking/lockdep.c                                      |    2 
 b/kernel/rcu/Kconfig                                            |    2 
 b/kernel/rcu/rcu.h                                              |    4 
 b/kernel/rcu/tree.c                                             |   14 
 b/kernel/rcu/tree.h                                             |    1 
 b/kernel/rcu/tree_exp.h                                         |    2 
 b/kernel/rcu/tree_plugin.h                                      |   38 
 b/kernel/rcu/tree_stall.h                                       |   49 
 b/kernel/rcu/update.c                                           |    2 
 b/kernel/sched/core.c                                           |    2 
 b/kernel/sched/idle.c                                           |   10 
 b/kernel/sched/sched.h                                          |    1 
 b/kernel/softirq.c                                              |    4 
 b/kernel/time/Kconfig                                           |   31 
 b/kernel/time/tick-sched.c                                      |    2 
 b/kernel/trace/trace.c                                          |    6 
 include/linux/context_tracking.h                                |   91 -
 include/linux/context_tracking_irq.h                            |    4 
 include/linux/context_tracking_state.h                          |  144 +
 include/linux/hardirq.h                                         |    8 
 include/linux/rcupdate.h                                        |   19 
 include/linux/rcutiny.h                                         |    2 
 include/linux/rcutree.h                                         |    5 
 kernel/context_tracking.c                                       |  808 +++++++---
 kernel/entry/common.c                                           |    4 
 kernel/rcu/tree.c                                               |  572 -------
 kernel/rcu/tree.h                                               |    7 
 kernel/rcu/tree_stall.h                                         |   12 
 kernel/time/Kconfig                                             |    6 
 kernel/trace/trace.c                                            |    2 
 78 files changed, 1142 insertions(+), 986 deletions(-)

[PATCH rcu 21/23] rcu/context_tracking: Merge dynticks counter and context tracking states

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Updating the context tracking state and the RCU dynticks counter
atomically in a single operation is a first step towards improving CPU
isolation. This makes the context tracking state updates fully ordered
and therefore allow for later enhancements such as postponing some work
while a task is running isolated in userspace until it ever comes back
to the kernel.

The state field becomes divided in two parts:

1) Two Lower bits for context tracking state:

	CONTEXT_KERNEL = 0
   	CONTEXT_IDLE = 1,
	CONTEXT_USER = 2,
	CONTEXT_GUEST = 3,

2) Higher bits for RCU eqs dynticks counting:

    RCU_DYNTICKS_IDX = 4

   The dynticks counting is always incremented by this value.
   (state & RCU_DYNTICKS_IDX) means we are NOT in an extended quiescent
   state. This makes the chance for a collision more likely between two
   RCU dynticks snapshots but wrapping up 28 bits of eqs dynticks
   increments still takes some bad luck (also rdp.dynticks_snap could be
   converted from int to long?)

Some RCU eqs functions have been renamed to better reflect their broader
scope that now include context tracking state.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/linux/context_tracking.h       |   8 +-
 include/linux/context_tracking_state.h |  35 ++++---
 kernel/context_tracking.c              | 132 ++++++++++++++++---------
 kernel/rcu/tree.c                      |  13 ++-
 kernel/rcu/tree_stall.h                |   4 +-
 5 files changed, 121 insertions(+), 71 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index a8c1db0a3f65a..fd354eaea510a 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -118,16 +118,16 @@ extern void ct_idle_exit(void);
  */
 static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
 {
-	return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1);
+	return !(arch_atomic_read(this_cpu_ptr(&context_tracking.state)) & RCU_DYNTICKS_IDX);
 }
 
 /*
- * Increment the current CPU's context_tracking structure's ->dynticks field
+ * Increment the current CPU's context_tracking structure's ->state field
  * with ordering.  Return the new value.
  */
-static __always_inline unsigned long rcu_dynticks_inc(int incby)
+static __always_inline unsigned long ct_state_inc(int incby)
 {
-	return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynticks));
+	return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state));
 }
 
 #else
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 7d2dddf0da690..0aecc07fb4f50 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -10,12 +10,20 @@
 #define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
 
 enum ctx_state {
-	CONTEXT_DISABLED = -1,	/* returned by ct_state() if unknown */
-	CONTEXT_KERNEL = 0,
-	CONTEXT_USER,
-	CONTEXT_GUEST,
+	CONTEXT_DISABLED	= -1,	/* returned by ct_state() if unknown */
+	CONTEXT_KERNEL		= 0,
+	CONTEXT_IDLE		= 1,
+	CONTEXT_USER		= 2,
+	CONTEXT_GUEST		= 3,
+	CONTEXT_MAX		= 4,
 };
 
+/* Even value for idle, else odd. */
+#define RCU_DYNTICKS_IDX CONTEXT_MAX
+
+#define CT_STATE_MASK (CONTEXT_MAX - 1)
+#define CT_DYNTICKS_MASK (~CT_STATE_MASK)
+
 struct context_tracking {
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 	/*
@@ -26,10 +34,11 @@ struct context_tracking {
 	 */
 	bool active;
 	int recursion;
+#endif
+#ifdef CONFIG_CONTEXT_TRACKING
 	atomic_t state;
 #endif
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
-	atomic_t dynticks;		/* Even value for idle, else odd. */
 	long dynticks_nesting;		/* Track process nesting level. */
 	long dynticks_nmi_nesting;	/* Track irq/NMI nesting level. */
 #endif
@@ -37,24 +46,29 @@ struct context_tracking {
 
 #ifdef CONFIG_CONTEXT_TRACKING
 DECLARE_PER_CPU(struct context_tracking, context_tracking);
+
+static __always_inline int __ct_state(void)
+{
+	return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
+}
 #endif
 
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 static __always_inline int ct_dynticks(void)
 {
-	return atomic_read(this_cpu_ptr(&context_tracking.dynticks));
+	return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_DYNTICKS_MASK;
 }
 
 static __always_inline int ct_dynticks_cpu(int cpu)
 {
 	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
-	return atomic_read(&ct->dynticks);
+	return atomic_read(&ct->state) & CT_DYNTICKS_MASK;
 }
 
 static __always_inline int ct_dynticks_cpu_acquire(int cpu)
 {
 	struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
-	return atomic_read_acquire(&ct->dynticks);
+	return atomic_read_acquire(&ct->state) & CT_DYNTICKS_MASK;
 }
 
 static __always_inline long ct_dynticks_nesting(void)
@@ -98,11 +112,6 @@ static inline bool context_tracking_enabled_this_cpu(void)
 	return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
 }
 
-static __always_inline int __ct_state(void)
-{
-	return atomic_read(this_cpu_ptr(&context_tracking.state));
-}
-
 /**
  * ct_state() - return the current context tracking state if known
  *
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index c477c7d696e0f..d373fad7c0cba 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -28,8 +28,8 @@ DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 	.dynticks_nesting = 1,
 	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
-	.dynticks = ATOMIC_INIT(1),
 #endif
+	.state = ATOMIC_INIT(RCU_DYNTICKS_IDX),
 };
 EXPORT_SYMBOL_GPL(context_tracking);
 
@@ -76,7 +76,7 @@ static __always_inline void rcu_dynticks_task_trace_exit(void)
  * RCU is watching prior to the call to this function and is no longer
  * watching upon return.
  */
-static noinstr void rcu_dynticks_eqs_enter(void)
+static noinstr void ct_kernel_exit_state(int offset)
 {
 	int seq;
 
@@ -86,9 +86,9 @@ static noinstr void rcu_dynticks_eqs_enter(void)
 	 * next idle sojourn.
 	 */
 	rcu_dynticks_task_trace_enter();  // Before ->dynticks update!
-	seq = rcu_dynticks_inc(1);
+	seq = ct_state_inc(offset);
 	// RCU is no longer watching.  Better be in extended quiescent state!
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1));
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & RCU_DYNTICKS_IDX));
 }
 
 /*
@@ -96,7 +96,7 @@ static noinstr void rcu_dynticks_eqs_enter(void)
  * called from an extended quiescent state, that is, RCU is not watching
  * prior to the call to this function and is watching upon return.
  */
-static noinstr void rcu_dynticks_eqs_exit(void)
+static noinstr void ct_kernel_enter_state(int offset)
 {
 	int seq;
 
@@ -105,10 +105,10 @@ static noinstr void rcu_dynticks_eqs_exit(void)
 	 * and we also must force ordering with the next RCU read-side
 	 * critical section.
 	 */
-	seq = rcu_dynticks_inc(1);
+	seq = ct_state_inc(offset);
 	// RCU is now watching.  Better not be in an extended quiescent state!
 	rcu_dynticks_task_trace_exit();  // After ->dynticks update!
-	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1));
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & RCU_DYNTICKS_IDX));
 }
 
 /*
@@ -119,7 +119,7 @@ static noinstr void rcu_dynticks_eqs_exit(void)
  * the possibility of usermode upcalls having messed up our count
  * of interrupt nesting level during the prior busy period.
  */
-static void noinstr rcu_eqs_enter(bool user)
+static void noinstr ct_kernel_exit(bool user, int offset)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
@@ -139,13 +139,13 @@ static void noinstr rcu_eqs_enter(bool user)
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	rcu_preempt_deferred_qs(current);
 
-	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
-	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+	// instrumentation for the noinstr ct_kernel_exit_state()
+	instrument_atomic_write(&ct->state, sizeof(ct->state));
 
 	instrumentation_end();
 	WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */
 	// RCU is watching here ...
-	rcu_dynticks_eqs_enter();
+	ct_kernel_exit_state(offset);
 	// ... but is no longer watching here.
 	rcu_dynticks_task_enter();
 }
@@ -158,7 +158,7 @@ static void noinstr rcu_eqs_enter(bool user)
  * allow for the possibility of usermode upcalls messing up our count of
  * interrupt nesting level during the busy period that is just now starting.
  */
-static void noinstr rcu_eqs_exit(bool user)
+static void noinstr ct_kernel_enter(bool user, int offset)
 {
 	struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 	long oldval;
@@ -173,12 +173,12 @@ static void noinstr rcu_eqs_exit(bool user)
 	}
 	rcu_dynticks_task_exit();
 	// RCU is not watching here ...
-	rcu_dynticks_eqs_exit();
+	ct_kernel_enter_state(offset);
 	// ... but is watching here.
 	instrumentation_begin();
 
-	// instrumentation for the noinstr rcu_dynticks_eqs_exit()
-	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+	// instrumentation for the noinstr ct_kernel_enter_state()
+	instrument_atomic_write(&ct->state, sizeof(ct->state));
 
 	trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
@@ -192,7 +192,7 @@ static void noinstr rcu_eqs_exit(bool user)
  * ct_nmi_exit - inform RCU of exit from NMI context
  *
  * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting
+ * RCU-idle period, update ct->state and ct->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
@@ -229,12 +229,12 @@ void noinstr ct_nmi_exit(void)
 	trace_rcu_dyntick(TPS("Startirq"), ct_dynticks_nmi_nesting(), 0, ct_dynticks());
 	WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 
-	// instrumentation for the noinstr rcu_dynticks_eqs_enter()
-	instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+	// instrumentation for the noinstr ct_kernel_exit_state()
+	instrument_atomic_write(&ct->state, sizeof(ct->state));
 	instrumentation_end();
 
 	// RCU is watching here ...
-	rcu_dynticks_eqs_enter();
+	ct_kernel_exit_state(RCU_DYNTICKS_IDX);
 	// ... but is no longer watching here.
 
 	if (!in_nmi())
@@ -244,7 +244,7 @@ void noinstr ct_nmi_exit(void)
 /**
  * ct_nmi_enter - inform RCU of entry to NMI context
  *
- * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
+ * If the CPU was idle from RCU's viewpoint, update ct->state and
  * ct->dynticks_nmi_nesting to let the RCU grace-period handling know
  * that the CPU is active.  This implementation permits nested NMIs, as
  * long as the nesting level does not overflow an int.  (You will probably
@@ -275,14 +275,14 @@ void noinstr ct_nmi_enter(void)
 			rcu_dynticks_task_exit();
 
 		// RCU is not watching here ...
-		rcu_dynticks_eqs_exit();
+		ct_kernel_enter_state(RCU_DYNTICKS_IDX);
 		// ... but is watching here.
 
 		instrumentation_begin();
 		// instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs()
-		instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks));
-		// instrumentation for the noinstr rcu_dynticks_eqs_exit()
-		instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
+		instrument_atomic_read(&ct->state, sizeof(ct->state));
+		// instrumentation for the noinstr ct_kernel_enter_state()
+		instrument_atomic_write(&ct->state, sizeof(ct->state));
 
 		incby = 1;
 	} else if (!in_nmi()) {
@@ -315,7 +315,7 @@ void noinstr ct_nmi_enter(void)
 void noinstr ct_idle_enter(void)
 {
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
-	rcu_eqs_enter(false);
+	ct_kernel_exit(false, RCU_DYNTICKS_IDX + CONTEXT_IDLE);
 }
 EXPORT_SYMBOL_GPL(ct_idle_enter);
 
@@ -333,7 +333,7 @@ void noinstr ct_idle_exit(void)
 	unsigned long flags;
 
 	raw_local_irq_save(flags);
-	rcu_eqs_exit(false);
+	ct_kernel_enter(false, RCU_DYNTICKS_IDX - CONTEXT_IDLE);
 	raw_local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(ct_idle_exit);
@@ -421,8 +421,8 @@ void ct_irq_exit_irqson(void)
 	local_irq_restore(flags);
 }
 #else
-static __always_inline void rcu_eqs_enter(bool user) { }
-static __always_inline void rcu_eqs_exit(bool user) { }
+static __always_inline void ct_kernel_exit(bool user, int offset) { }
+static __always_inline void ct_kernel_enter(bool user, int offset) { }
 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
 
 #ifdef CONFIG_CONTEXT_TRACKING_USER
@@ -493,28 +493,49 @@ void noinstr __ct_user_enter(enum ctx_state state)
 			 * that will fire and reschedule once we resume in user/guest mode.
 			 */
 			rcu_irq_work_resched();
+
 			/*
 			 * Enter RCU idle mode right before resuming userspace.  No use of RCU
 			 * is permitted between this call and rcu_eqs_exit(). This way the
 			 * CPU doesn't need to maintain the tick for RCU maintenance purposes
 			 * when the CPU runs in userspace.
 			 */
-			rcu_eqs_enter(true);
+			ct_kernel_exit(true, RCU_DYNTICKS_IDX + state);
+
+			/*
+			 * Special case if we only track user <-> kernel transitions for tickless
+			 * cputime accounting but we don't support RCU extended quiescent state.
+			 * In this we case we don't care about any concurrency/ordering.
+			 */
+			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE))
+				atomic_set(&ct->state, state);
+		} else {
+			/*
+			 * Even if context tracking is disabled on this CPU, because it's outside
+			 * the full dynticks mask for example, we still have to keep track of the
+			 * context transitions and states to prevent inconsistency on those of
+			 * other CPUs.
+			 * If a task triggers an exception in userspace, sleep on the exception
+			 * handler and then migrate to another CPU, that new CPU must know where
+			 * the exception returns by the time we call exception_exit().
+			 * This information can only be provided by the previous CPU when it called
+			 * exception_enter().
+			 * OTOH we can spare the calls to vtime and RCU when context_tracking.active
+			 * is false because we know that CPU is not tickless.
+			 */
+			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE)) {
+				/* Tracking for vtime only, no concurrent RCU EQS accounting */
+				atomic_set(&ct->state, state);
+			} else {
+				/*
+				 * Tracking for vtime and RCU EQS. Make sure we don't race
+				 * with NMIs. OTOH we don't care about ordering here since
+				 * RCU only requires RCU_DYNTICKS_IDX increments to be fully
+				 * ordered.
+				 */
+				atomic_add(state, &ct->state);
+			}
 		}
-		/*
-		 * Even if context tracking is disabled on this CPU, because it's outside
-		 * the full dynticks mask for example, we still have to keep track of the
-		 * context transitions and states to prevent inconsistency on those of
-		 * other CPUs.
-		 * If a task triggers an exception in userspace, sleep on the exception
-		 * handler and then migrate to another CPU, that new CPU must know where
-		 * the exception returns by the time we call exception_exit().
-		 * This information can only be provided by the previous CPU when it called
-		 * exception_enter().
-		 * OTOH we can spare the calls to vtime and RCU when context_tracking.active
-		 * is false because we know that CPU is not tickless.
-		 */
-		atomic_set(&ct->state, state);
 	}
 	context_tracking_recursion_exit();
 }
@@ -593,15 +614,36 @@ void noinstr __ct_user_exit(enum ctx_state state)
 			 * Exit RCU idle mode while entering the kernel because it can
 			 * run a RCU read side critical section anytime.
 			 */
-			rcu_eqs_exit(true);
+			ct_kernel_enter(true, RCU_DYNTICKS_IDX - state);
 			if (state == CONTEXT_USER) {
 				instrumentation_begin();
 				vtime_user_exit(current);
 				trace_user_exit(0);
 				instrumentation_end();
 			}
+
+			/*
+			 * Special case if we only track user <-> kernel transitions for tickless
+			 * cputime accounting but we don't support RCU extended quiescent state.
+			 * In this we case we don't care about any concurrency/ordering.
+			 */
+			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE))
+				atomic_set(&ct->state, CONTEXT_KERNEL);
+
+		} else {
+			if (!IS_ENABLED(CONFIG_CONTEXT_TRACKING_IDLE)) {
+				/* Tracking for vtime only, no concurrent RCU EQS accounting */
+				atomic_set(&ct->state, CONTEXT_KERNEL);
+			} else {
+				/*
+				 * Tracking for vtime and RCU EQS. Make sure we don't race
+				 * with NMIs. OTOH we don't care about ordering here since
+				 * RCU only requires RCU_DYNTICKS_IDX increments to be fully
+				 * ordered.
+				 */
+				atomic_sub(state, &ct->state);
+			}
 		}
-		atomic_set(&ct->state, CONTEXT_KERNEL);
 	}
 	context_tracking_recursion_exit();
 }
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e2a2083079a2c..f9d20b40071f3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -272,9 +272,9 @@ void rcu_softirq_qs(void)
  */
 static void rcu_dynticks_eqs_online(void)
 {
-	if (ct_dynticks() & 0x1)
+	if (ct_dynticks() & RCU_DYNTICKS_IDX)
 		return;
-	rcu_dynticks_inc(1);
+	ct_state_inc(RCU_DYNTICKS_IDX);
 }
 
 /*
@@ -293,7 +293,7 @@ static int rcu_dynticks_snap(int cpu)
  */
 static bool rcu_dynticks_in_eqs(int snap)
 {
-	return !(snap & 0x1);
+	return !(snap & RCU_DYNTICKS_IDX);
 }
 
 /* Return true if the specified CPU is currently idle from an RCU viewpoint.  */
@@ -321,8 +321,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp)
 	int snap;
 
 	// If not quiescent, force back to earlier extended quiescent state.
-	snap = ct_dynticks_cpu(cpu) & ~0x1;
-
+	snap = ct_dynticks_cpu(cpu) & ~RCU_DYNTICKS_IDX;
 	smp_rmb(); // Order ->dynticks and *vp reads.
 	if (READ_ONCE(*vp))
 		return false;  // Non-zero, so report failure;
@@ -348,9 +347,9 @@ notrace void rcu_momentary_dyntick_idle(void)
 	int seq;
 
 	raw_cpu_write(rcu_data.rcu_need_heavy_qs, false);
-	seq = rcu_dynticks_inc(2);
+	seq = ct_state_inc(2 * RCU_DYNTICKS_IDX);
 	/* It is illegal to call this from idle state. */
-	WARN_ON_ONCE(!(seq & 0x1));
+	WARN_ON_ONCE(!(seq & RCU_DYNTICKS_IDX));
 	rcu_preempt_deferred_qs(current);
 }
 EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle);
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 2683ce0a7c724..195cad14742dd 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -469,7 +469,7 @@ static void print_cpu_stall_info(int cpu)
 	rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j);
 	if (rcuc_starved)
 		sprintf(buf, " rcuc=%ld jiffies(starved)", j);
-	pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%#lx softirq=%u/%u fqs=%ld%s%s\n",
+	pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%04x/%ld/%#lx softirq=%u/%u fqs=%ld%s%s\n",
 	       cpu,
 	       "O."[!!cpu_online(cpu)],
 	       "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
@@ -478,7 +478,7 @@ static void print_cpu_stall_info(int cpu)
 			rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
 				"!."[!delta],
 	       ticks_value, ticks_title,
-	       rcu_dynticks_snap(cpu) & 0xfff,
+	       rcu_dynticks_snap(cpu) & 0xffff,
 	       ct_dynticks_nesting_cpu(cpu), ct_dynticks_nmi_nesting_cpu(cpu),
 	       rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
 	       data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 22/23] MAINTAINERS: Add Paul as context tracking maintainer

[Paul E. McKenney]

From: Frederic Weisbecker <frederic@kernel.org>

Since most of the bits have been imported from kernel/rcu/tree.c and
now that the context tracking code is tightly linked to RCU, add Paul
as a context tracking maintainer.

Also update the context tracking file header accordingly.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 MAINTAINERS               |  1 +
 kernel/context_tracking.c | 12 +++++++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 3cf9842d9233c..4e38d7533cbe9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5039,6 +5039,7 @@ F:	include/linux/console*
 
 CONTEXT TRACKING
 M:	Frederic Weisbecker <frederic@kernel.org>
+M:	"Paul E. McKenney" <paulmck@kernel.org>
 S:	Maintained
 F:	kernel/context_tracking.c
 F:	include/linux/context_tracking*
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index d373fad7c0cba..1da44803fd319 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -1,18 +1,20 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Context tracking: Probe on high level context boundaries such as kernel
- * and userspace. This includes syscalls and exceptions entry/exit.
+ * Context tracking: Probe on high level context boundaries such as kernel,
+ * userspace, guest or idle.
  *
  * This is used by RCU to remove its dependency on the timer tick while a CPU
- * runs in userspace.
+ * runs in idle, userspace or guest mode.
  *
- *  Started by Frederic Weisbecker:
+ * User/guest tracking started by Frederic Weisbecker:
  *
- * Copyright (C) 2012 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
+ * Copyright (C) 2012 Red Hat, Inc., Frederic Weisbecker
  *
  * Many thanks to Gilad Ben-Yossef, Paul McKenney, Ingo Molnar, Andrew Morton,
  * Steven Rostedt, Peter Zijlstra for suggestions and improvements.
  *
+ * RCU extended quiescent state bits imported from kernel/rcu/tree.c
+ * where the relevant authorship may be found.
  */
 
 #include <linux/context_tracking.h>
-- 
2.31.1.189.g2e36527f23

[PATCH rcu 23/23] context_tracking: Interrupts always disabled for ct_idle_exit()

[Paul E. McKenney]

From: Peter Zijlstra <peterz@infradead.org>

Now that the idle-loop cleanups have ensured that rcu_idle_exit() is
always invoked with interrupts disabled, remove the interrupt disabling
in favor of a debug check.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/context_tracking.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 1da44803fd319..99310cf5b0254 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -332,11 +332,8 @@ EXPORT_SYMBOL_GPL(ct_idle_enter);
  */
 void noinstr ct_idle_exit(void)
 {
-	unsigned long flags;
-
-	raw_local_irq_save(flags);
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled());
 	ct_kernel_enter(false, RCU_DYNTICKS_IDX - CONTEXT_IDLE);
-	raw_local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(ct_idle_exit);
 
-- 
2.31.1.189.g2e36527f23