* [PATCH tip/core/rcu 1/3] srcu: Fix a typo in comment "amoritized"->"amortized"
2020-06-23 0:33 [PATCH tip/core/rcu 0/3] SRCU updates for v5.9 Paul E. McKenney
@ 2020-06-23 0:33 ` paulmck
2020-06-23 0:33 ` [PATCH tip/core/rcu 2/3] srcu: Avoid local_irq_save() before acquiring spinlock_t paulmck
2020-06-23 0:33 ` [PATCH tip/core/rcu 3/3] srcu: Remove KCSAN stubs paulmck
2 siblings, 0 replies; 4+ messages in thread
From: paulmck @ 2020-06-23 0:33 UTC (permalink / raw)
To: rcu
Cc: linux-kernel, kernel-team, mingo, jiangshanlai, dipankar, akpm,
mathieu.desnoyers, josh, tglx, peterz, rostedt, dhowells,
edumazet, fweisbec, oleg, joel, Ethon Paul, Paul E . McKenney
From: Ethon Paul <ethp@qq.com>
This commit fixes a typo in a comment.
Signed-off-by: Ethon Paul <ethp@qq.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/srcutree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 6d3ef70..8ff71e5 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -766,7 +766,7 @@ static void srcu_flip(struct srcu_struct *ssp)
* it, if this function was preempted for enough time for the counters
* to wrap, it really doesn't matter whether or not we expedite the grace
* period. The extra overhead of a needlessly expedited grace period is
- * negligible when amoritized over that time period, and the extra latency
+ * negligible when amortized over that time period, and the extra latency
* of a needlessly non-expedited grace period is similarly negligible.
*/
static bool srcu_might_be_idle(struct srcu_struct *ssp)
--
2.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH tip/core/rcu 2/3] srcu: Avoid local_irq_save() before acquiring spinlock_t
2020-06-23 0:33 [PATCH tip/core/rcu 0/3] SRCU updates for v5.9 Paul E. McKenney
2020-06-23 0:33 ` [PATCH tip/core/rcu 1/3] srcu: Fix a typo in comment "amoritized"->"amortized" paulmck
@ 2020-06-23 0:33 ` paulmck
2020-06-23 0:33 ` [PATCH tip/core/rcu 3/3] srcu: Remove KCSAN stubs paulmck
2 siblings, 0 replies; 4+ messages in thread
From: paulmck @ 2020-06-23 0:33 UTC (permalink / raw)
To: rcu
Cc: linux-kernel, kernel-team, mingo, jiangshanlai, dipankar, akpm,
mathieu.desnoyers, josh, tglx, peterz, rostedt, dhowells,
edumazet, fweisbec, oleg, joel, Sebastian Andrzej Siewior,
Paul E. McKenney
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
SRCU disables interrupts to get a stable per-CPU pointer and then
acquires the spinlock which is in the per-CPU data structure. The
release uses spin_unlock_irqrestore(). While this is correct on a non-RT
kernel, this conflicts with the RT semantics because the spinlock is
converted to a 'sleeping' spinlock. Sleeping locks can obviously not be
acquired with interrupts disabled.
Acquire the per-CPU pointer `ssp->sda' without disabling preemption and
then acquire the spinlock_t of the per-CPU data structure. The lock will
ensure that the data is consistent.
The added call to check_init_srcu_struct() is now needed because a
statically defined srcu_struct may remain uninitialized until this
point and the newly introduced locking operation requires an initialized
spinlock_t.
This change was tested for four hours with 8*SRCU-N and 8*SRCU-P without
causing any warnings.
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: rcu@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/srcutree.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 8ff71e5..c100acf 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -777,14 +777,15 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp)
unsigned long t;
unsigned long tlast;
+ check_init_srcu_struct(ssp);
/* If the local srcu_data structure has callbacks, not idle. */
- local_irq_save(flags);
- sdp = this_cpu_ptr(ssp->sda);
+ sdp = raw_cpu_ptr(ssp->sda);
+ spin_lock_irqsave_rcu_node(sdp, flags);
if (rcu_segcblist_pend_cbs(&sdp->srcu_cblist)) {
- local_irq_restore(flags);
+ spin_unlock_irqrestore_rcu_node(sdp, flags);
return false; /* Callbacks already present, so not idle. */
}
- local_irq_restore(flags);
+ spin_unlock_irqrestore_rcu_node(sdp, flags);
/*
* No local callbacks, so probabalistically probe global state.
@@ -864,9 +865,8 @@ static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
}
rhp->func = func;
idx = srcu_read_lock(ssp);
- local_irq_save(flags);
- sdp = this_cpu_ptr(ssp->sda);
- spin_lock_rcu_node(sdp);
+ sdp = raw_cpu_ptr(ssp->sda);
+ spin_lock_irqsave_rcu_node(sdp, flags);
rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp);
rcu_segcblist_advance(&sdp->srcu_cblist,
rcu_seq_current(&ssp->srcu_gp_seq));
--
2.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH tip/core/rcu 3/3] srcu: Remove KCSAN stubs
2020-06-23 0:33 [PATCH tip/core/rcu 0/3] SRCU updates for v5.9 Paul E. McKenney
2020-06-23 0:33 ` [PATCH tip/core/rcu 1/3] srcu: Fix a typo in comment "amoritized"->"amortized" paulmck
2020-06-23 0:33 ` [PATCH tip/core/rcu 2/3] srcu: Avoid local_irq_save() before acquiring spinlock_t paulmck
@ 2020-06-23 0:33 ` paulmck
2 siblings, 0 replies; 4+ messages in thread
From: paulmck @ 2020-06-23 0:33 UTC (permalink / raw)
To: rcu
Cc: linux-kernel, kernel-team, mingo, jiangshanlai, dipankar, akpm,
mathieu.desnoyers, josh, tglx, peterz, rostedt, dhowells,
edumazet, fweisbec, oleg, joel, Paul E. McKenney
From: "Paul E. McKenney" <paulmck@kernel.org>
KCSAN is now in mainline, so this commit removes the stubs for the
data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS()
macros.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/srcutree.c | 13 -------------
1 file changed, 13 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index c100acf..c13348e 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -29,19 +29,6 @@
#include "rcu.h"
#include "rcu_segcblist.h"
-#ifndef data_race
-#define data_race(expr) \
- ({ \
- expr; \
- })
-#endif
-#ifndef ASSERT_EXCLUSIVE_WRITER
-#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
-#endif
-#ifndef ASSERT_EXCLUSIVE_ACCESS
-#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
-#endif
-
/* Holdoff in nanoseconds for auto-expediting. */
#define DEFAULT_SRCU_EXP_HOLDOFF (25 * 1000)
static ulong exp_holdoff = DEFAULT_SRCU_EXP_HOLDOFF;
--
2.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread