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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH v2 tip/core/rcu 35/39] srcu: Create a tiny SRCU
Date: Mon, 17 Apr 2017 16:45:22 -0700	[thread overview]
Message-ID: <1492472726-3841-35-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170417234452.GB19013@linux.vnet.ibm.com>

In response to automated complaints about modifications to SRCU
increasing its size, this commit creates a tiny SRCU that is
used in SMP=n && PREEMPT=n builds.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/srcu.h     |  69 ++-------------
 include/linux/srcutiny.h |  81 ++++++++++++++++++
 include/linux/srcutree.h |  91 ++++++++++++++++++++
 init/Kconfig             |  12 +++
 kernel/rcu/Makefile      |   3 +-
 kernel/rcu/rcutorture.c  |   2 +
 kernel/rcu/srcutiny.c    | 215 +++++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 411 insertions(+), 62 deletions(-)
 create mode 100644 include/linux/srcutiny.h
 create mode 100644 include/linux/srcutree.h
 create mode 100644 kernel/rcu/srcutiny.c

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 73a1b6296224..907f09b14eda 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -34,28 +34,7 @@
 #include <linux/workqueue.h>
 #include <linux/rcu_segcblist.h>
 
-struct srcu_array {
-	unsigned long lock_count[2];
-	unsigned long unlock_count[2];
-};
-
-struct srcu_struct {
-	unsigned long completed;
-	unsigned long srcu_gp_seq;
-	atomic_t srcu_exp_cnt;
-	struct srcu_array __percpu *per_cpu_ref;
-	spinlock_t queue_lock; /* protect ->srcu_cblist */
-	struct rcu_segcblist srcu_cblist;
-	struct delayed_work work;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map dep_map;
-#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
-};
-
-/* Values for -> state variable. */
-#define SRCU_STATE_IDLE		0
-#define SRCU_STATE_SCAN1	1
-#define SRCU_STATE_SCAN2	2
+struct srcu_struct;
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
@@ -77,42 +56,13 @@ int init_srcu_struct(struct srcu_struct *sp);
 #define __SRCU_DEP_MAP_INIT(srcu_name)
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
-void process_srcu(struct work_struct *work);
-
-#define __SRCU_STRUCT_INIT(name)					\
-	{								\
-		.completed = -300,					\
-		.per_cpu_ref = &name##_srcu_array,			\
-		.queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock),	\
-		.srcu_cblist = RCU_SEGCBLIST_INITIALIZER(name.srcu_cblist),\
-		.work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
-		__SRCU_DEP_MAP_INIT(name)				\
-	}
-
-/*
- * Define and initialize a srcu struct at build time.
- * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
- *
- * Note that although DEFINE_STATIC_SRCU() hides the name from other
- * files, the per-CPU variable rules nevertheless require that the
- * chosen name be globally unique.  These rules also prohibit use of
- * DEFINE_STATIC_SRCU() within a function.  If these rules are too
- * restrictive, declare the srcu_struct manually.  For example, in
- * each file:
- *
- *	static struct srcu_struct my_srcu;
- *
- * Then, before the first use of each my_srcu, manually initialize it:
- *
- *	init_srcu_struct(&my_srcu);
- *
- * See include/linux/percpu-defs.h for the rules on per-CPU variables.
- */
-#define __DEFINE_SRCU(name, is_static)					\
-	static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
-	is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
-#define DEFINE_SRCU(name)		__DEFINE_SRCU(name, /* not static */)
-#define DEFINE_STATIC_SRCU(name)	__DEFINE_SRCU(name, static)
+#ifdef CONFIG_TINY_SRCU
+#include <linux/srcutiny.h>
+#elif defined(CONFIG_TREE_SRCU)
+#include <linux/srcutree.h>
+#else
+#error "Unknown SRCU implementation specified to kernel configuration"
+#endif
 
 /**
  * call_srcu() - Queue a callback for invocation after an SRCU grace period
@@ -138,9 +88,6 @@ void cleanup_srcu_struct(struct srcu_struct *sp);
 int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
 void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
 void synchronize_srcu(struct srcu_struct *sp);
-void synchronize_srcu_expedited(struct srcu_struct *sp);
-unsigned long srcu_batches_completed(struct srcu_struct *sp);
-void srcu_barrier(struct srcu_struct *sp);
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
new file mode 100644
index 000000000000..4f284e4f4d8c
--- /dev/null
+++ b/include/linux/srcutiny.h
@@ -0,0 +1,81 @@
+/*
+ * Sleepable Read-Copy Update mechanism for mutual exclusion,
+ *	tiny variant.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright (C) IBM Corporation, 2017
+ *
+ * Author: Paul McKenney <paulmck@us.ibm.com>
+ */
+
+#ifndef _LINUX_SRCU_TINY_H
+#define _LINUX_SRCU_TINY_H
+
+#include <linux/swait.h>
+
+struct srcu_struct {
+	int srcu_lock_nesting[2];	/* srcu_read_lock() nesting depth. */
+	struct swait_queue_head srcu_wq;
+					/* Last srcu_read_unlock() wakes GP. */
+	unsigned long srcu_gp_seq;	/* GP seq # for callback tagging. */
+	struct rcu_segcblist srcu_cblist;
+					/* Pending SRCU callbacks. */
+	int srcu_idx;			/* Current reader array element. */
+	bool srcu_gp_running;		/* GP workqueue running? */
+	bool srcu_gp_waiting;		/* GP waiting for readers? */
+	struct work_struct srcu_work;	/* For driving grace periods. */
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map dep_map;
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+};
+
+void srcu_drive_gp(struct work_struct *wp);
+
+#define __SRCU_STRUCT_INIT(name)					\
+{									\
+	.srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq),	\
+	.srcu_cblist = RCU_SEGCBLIST_INITIALIZER(name.srcu_cblist),	\
+	.srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp),	\
+	__SRCU_DEP_MAP_INIT(name)					\
+}
+
+/*
+ * This odd _STATIC_ arrangement is needed for API compatibility with
+ * Tree SRCU, which needs some per-CPU data.
+ */
+#define DEFINE_SRCU(name) \
+	struct srcu_struct name = __SRCU_STRUCT_INIT(name)
+#define DEFINE_STATIC_SRCU(name) \
+	static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
+
+void synchronize_srcu(struct srcu_struct *sp);
+
+static inline void synchronize_srcu_expedited(struct srcu_struct *sp)
+{
+	synchronize_srcu(sp);
+}
+
+static inline void srcu_barrier(struct srcu_struct *sp)
+{
+	synchronize_srcu(sp);
+}
+
+static inline unsigned long srcu_batches_completed(struct srcu_struct *sp)
+{
+	return 0;
+}
+
+#endif
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
new file mode 100644
index 000000000000..f2b3bd6c6bc2
--- /dev/null
+++ b/include/linux/srcutree.h
@@ -0,0 +1,91 @@
+/*
+ * Sleepable Read-Copy Update mechanism for mutual exclusion,
+ *	tree variant.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright (C) IBM Corporation, 2017
+ *
+ * Author: Paul McKenney <paulmck@us.ibm.com>
+ */
+
+#ifndef _LINUX_SRCU_TREE_H
+#define _LINUX_SRCU_TREE_H
+
+struct srcu_array {
+	unsigned long lock_count[2];
+	unsigned long unlock_count[2];
+};
+
+struct srcu_struct {
+	unsigned long completed;
+	unsigned long srcu_gp_seq;
+	atomic_t srcu_exp_cnt;
+	struct srcu_array __percpu *per_cpu_ref;
+	spinlock_t queue_lock; /* protect ->srcu_cblist */
+	struct rcu_segcblist srcu_cblist;
+	struct delayed_work work;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map dep_map;
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+};
+
+/* Values for -> state variable. */
+#define SRCU_STATE_IDLE		0
+#define SRCU_STATE_SCAN1	1
+#define SRCU_STATE_SCAN2	2
+
+void process_srcu(struct work_struct *work);
+
+#define __SRCU_STRUCT_INIT(name)					\
+	{								\
+		.completed = -300,					\
+		.per_cpu_ref = &name##_srcu_array,			\
+		.queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock),	\
+		.srcu_cblist = RCU_SEGCBLIST_INITIALIZER(name.srcu_cblist),\
+		.work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
+		__SRCU_DEP_MAP_INIT(name)				\
+	}
+
+/*
+ * Define and initialize a srcu struct at build time.
+ * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
+ *
+ * Note that although DEFINE_STATIC_SRCU() hides the name from other
+ * files, the per-CPU variable rules nevertheless require that the
+ * chosen name be globally unique.  These rules also prohibit use of
+ * DEFINE_STATIC_SRCU() within a function.  If these rules are too
+ * restrictive, declare the srcu_struct manually.  For example, in
+ * each file:
+ *
+ *	static struct srcu_struct my_srcu;
+ *
+ * Then, before the first use of each my_srcu, manually initialize it:
+ *
+ *	init_srcu_struct(&my_srcu);
+ *
+ * See include/linux/percpu-defs.h for the rules on per-CPU variables.
+ */
+#define __DEFINE_SRCU(name, is_static)					\
+	static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
+	is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
+#define DEFINE_SRCU(name)		__DEFINE_SRCU(name, /* not static */)
+#define DEFINE_STATIC_SRCU(name)	__DEFINE_SRCU(name, static)
+
+void synchronize_srcu_expedited(struct srcu_struct *sp);
+void srcu_barrier(struct srcu_struct *sp);
+unsigned long srcu_batches_completed(struct srcu_struct *sp);
+
+#endif
diff --git a/init/Kconfig b/init/Kconfig
index a92f27da4a27..d269f2ca17b8 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -526,6 +526,18 @@ config SRCU
 	  permits arbitrary sleeping or blocking within RCU read-side critical
 	  sections.
 
+config TINY_SRCU
+	bool
+	default y if TINY_RCU
+	help
+	  This option selects the single-CPU non-preemptible version of SRCU.
+
+config TREE_SRCU
+	bool
+	default y if !TINY_RCU
+	help
+	  This option selects the full-fledged version of SRCU.
+
 config TASKS_RCU
 	bool
 	default n
diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile
index 18dfc485225c..b853214a2b99 100644
--- a/kernel/rcu/Makefile
+++ b/kernel/rcu/Makefile
@@ -3,7 +3,8 @@
 KCOV_INSTRUMENT := n
 
 obj-y += update.o sync.o
-obj-$(CONFIG_SRCU) += srcu.o
+obj-$(CONFIG_TREE_SRCU) += srcu.o
+obj-$(CONFIG_TINY_SRCU) += srcutiny.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o
 obj-$(CONFIG_TREE_RCU) += tree.o
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index cccc417a8135..98591e16db1a 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -559,6 +559,7 @@ static void srcu_torture_barrier(void)
 
 static void srcu_torture_stats(void)
 {
+#ifdef CONFIG_TREE_SRCU
 	int cpu;
 	int idx = srcu_ctlp->completed & 0x1;
 
@@ -587,6 +588,7 @@ static void srcu_torture_stats(void)
 		pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 	}
 	pr_cont("\n");
+#endif
 }
 
 static void srcu_torture_synchronize_expedited(void)
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
new file mode 100644
index 000000000000..b8293527ee18
--- /dev/null
+++ b/kernel/rcu/srcutiny.c
@@ -0,0 +1,215 @@
+/*
+ * Sleepable Read-Copy Update mechanism for mutual exclusion,
+ *	tiny version for non-preemptible single-CPU use.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright (C) IBM Corporation, 2017
+ *
+ * Author: Paul McKenney <paulmck@us.ibm.com>
+ */
+
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/preempt.h>
+#include <linux/rcupdate_wait.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/srcu.h>
+
+#include <linux/rcu_node_tree.h>
+#include "rcu.h"
+
+static int init_srcu_struct_fields(struct srcu_struct *sp)
+{
+	sp->srcu_lock_nesting[0] = 0;
+	sp->srcu_lock_nesting[1] = 0;
+	init_swait_queue_head(&sp->srcu_wq);
+	sp->srcu_gp_seq = 0;
+	rcu_segcblist_init(&sp->srcu_cblist);
+	sp->srcu_gp_running = false;
+	sp->srcu_gp_waiting = false;
+	sp->srcu_idx = 0;
+	INIT_WORK(&sp->srcu_work, srcu_drive_gp);
+	return 0;
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+int __init_srcu_struct(struct srcu_struct *sp, const char *name,
+		       struct lock_class_key *key)
+{
+	/* Don't re-initialize a lock while it is held. */
+	debug_check_no_locks_freed((void *)sp, sizeof(*sp));
+	lockdep_init_map(&sp->dep_map, name, key, 0);
+	return init_srcu_struct_fields(sp);
+}
+EXPORT_SYMBOL_GPL(__init_srcu_struct);
+
+#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+/*
+ * init_srcu_struct - initialize a sleep-RCU structure
+ * @sp: structure to initialize.
+ *
+ * Must invoke this on a given srcu_struct before passing that srcu_struct
+ * to any other function.  Each srcu_struct represents a separate domain
+ * of SRCU protection.
+ */
+int init_srcu_struct(struct srcu_struct *sp)
+{
+	return init_srcu_struct_fields(sp);
+}
+EXPORT_SYMBOL_GPL(init_srcu_struct);
+
+#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+/*
+ * cleanup_srcu_struct - deconstruct a sleep-RCU structure
+ * @sp: structure to clean up.
+ *
+ * Must invoke this after you are finished using a given srcu_struct that
+ * was initialized via init_srcu_struct(), else you leak memory.
+ */
+void cleanup_srcu_struct(struct srcu_struct *sp)
+{
+	WARN_ON(sp->srcu_lock_nesting[0] || sp->srcu_lock_nesting[1]);
+	flush_work(&sp->srcu_work);
+	WARN_ON(rcu_seq_state(sp->srcu_gp_seq));
+	WARN_ON(sp->srcu_gp_running);
+	WARN_ON(sp->srcu_gp_waiting);
+	WARN_ON(!rcu_segcblist_empty(&sp->srcu_cblist));
+}
+EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
+
+/*
+ * Counts the new reader in the appropriate per-CPU element of the
+ * srcu_struct.  Must be called from process context.
+ * Returns an index that must be passed to the matching srcu_read_unlock().
+ */
+int __srcu_read_lock(struct srcu_struct *sp)
+{
+	int idx;
+
+	idx = READ_ONCE(sp->srcu_idx);
+	WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
+	return idx;
+}
+EXPORT_SYMBOL_GPL(__srcu_read_lock);
+
+/*
+ * Removes the count for the old reader from the appropriate element of
+ * the srcu_struct.  Must be called from process context.
+ */
+void __srcu_read_unlock(struct srcu_struct *sp, int idx)
+{
+	int newval = sp->srcu_lock_nesting[idx] - 1;
+
+	WRITE_ONCE(sp->srcu_lock_nesting[idx], newval);
+	if (!newval && READ_ONCE(sp->srcu_gp_waiting))
+		swake_up(&sp->srcu_wq);
+}
+EXPORT_SYMBOL_GPL(__srcu_read_unlock);
+
+/*
+ * Workqueue handler to drive one grace period and invoke any callbacks
+ * that become ready as a result.  Single-CPU and !PREEMPT operation
+ * means that we get away with murder on synchronization.  ;-)
+ */
+void srcu_drive_gp(struct work_struct *wp)
+{
+	int idx;
+	struct rcu_cblist ready_cbs;
+	struct srcu_struct *sp;
+	struct rcu_head *rhp;
+
+	sp = container_of(wp, struct srcu_struct, srcu_work);
+	if (sp->srcu_gp_running || rcu_segcblist_empty(&sp->srcu_cblist))
+		return; /* Already running or nothing to do. */
+
+	/* Tag recently arrived callbacks and wait for readers. */
+	WRITE_ONCE(sp->srcu_gp_running, true);
+	rcu_segcblist_accelerate(&sp->srcu_cblist,
+				 rcu_seq_snap(&sp->srcu_gp_seq));
+	rcu_seq_start(&sp->srcu_gp_seq);
+	idx = sp->srcu_idx;
+	WRITE_ONCE(sp->srcu_idx, !sp->srcu_idx);
+	WRITE_ONCE(sp->srcu_gp_waiting, true);  /* srcu_read_unlock() wakes! */
+	swait_event(sp->srcu_wq, !READ_ONCE(sp->srcu_lock_nesting[idx]));
+	WRITE_ONCE(sp->srcu_gp_waiting, false); /* srcu_read_unlock() cheap. */
+	rcu_seq_end(&sp->srcu_gp_seq);
+
+	/* Update callback list based on GP, and invoke ready callbacks. */
+	rcu_segcblist_advance(&sp->srcu_cblist,
+			      rcu_seq_current(&sp->srcu_gp_seq));
+	if (rcu_segcblist_ready_cbs(&sp->srcu_cblist)) {
+		rcu_cblist_init(&ready_cbs);
+		local_irq_disable();
+		rcu_segcblist_extract_done_cbs(&sp->srcu_cblist, &ready_cbs);
+		local_irq_enable();
+		rhp = rcu_cblist_dequeue(&ready_cbs);
+		for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) {
+			local_bh_disable();
+			rhp->func(rhp);
+			local_bh_enable();
+		}
+		local_irq_disable();
+		rcu_segcblist_insert_count(&sp->srcu_cblist, &ready_cbs);
+		local_irq_enable();
+	}
+	WRITE_ONCE(sp->srcu_gp_running, false);
+
+	/*
+	 * If more callbacks, reschedule ourselves.  This can race with
+	 * a call_srcu() at interrupt level, but the ->srcu_gp_running
+	 * checks will straighten that out.
+	 */
+	if (!rcu_segcblist_empty(&sp->srcu_cblist))
+		schedule_work(&sp->srcu_work);
+}
+EXPORT_SYMBOL_GPL(srcu_drive_gp);
+
+/*
+ * Enqueue an SRCU callback on the specified srcu_struct structure,
+ * initiating grace-period processing if it is not already running.
+ */
+void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
+	       rcu_callback_t func)
+{
+	unsigned long flags;
+
+	head->func = func;
+	local_irq_save(flags);
+	rcu_segcblist_enqueue(&sp->srcu_cblist, head, false);
+	local_irq_restore(flags);
+	if (!READ_ONCE(sp->srcu_gp_running))
+		schedule_work(&sp->srcu_work);
+}
+EXPORT_SYMBOL_GPL(call_srcu);
+
+/*
+ * synchronize_srcu - wait for prior SRCU read-side critical-section completion
+ */
+void synchronize_srcu(struct srcu_struct *sp)
+{
+	struct rcu_synchronize rs;
+
+	init_rcu_head_on_stack(&rs.head);
+	init_completion(&rs.completion);
+	call_srcu(sp, &rs.head, wakeme_after_rcu);
+	wait_for_completion(&rs.completion);
+	destroy_rcu_head_on_stack(&rs.head);
+}
+EXPORT_SYMBOL_GPL(synchronize_srcu);
-- 
2.5.2

  parent reply	other threads:[~2017-04-17 23:47 UTC|newest]

Thread overview: 176+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-12 17:40 [PATCH tip/core/rcu 0/40] SRCU callback parallelization for 4.12 Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 01/40] rcu: Maintain special bits at bottom of ->dynticks counter Paul E. McKenney
2017-04-13  9:20   ` Peter Zijlstra
2017-04-13 16:15     ` Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 02/40] rcu: Make arch select smp_mb__after_unlock_lock() strength Paul E. McKenney
2017-04-13  9:21   ` Peter Zijlstra
2017-04-13 16:17     ` Paul E. McKenney
2017-04-13  9:24   ` Peter Zijlstra
2017-04-13 16:26     ` Paul E. McKenney
2017-04-13 16:37       ` Peter Zijlstra
2017-04-13 17:03         ` Paul E. McKenney
2017-04-19 13:38           ` Michael Ellerman
2017-04-19 15:09             ` Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 03/40] srcu: Consolidate batch checking into rcu_all_batches_empty() Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 04/40] srcu: Check for tardy grace-period activity in cleanup_srcu_struct() Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 05/40] rcu: Semicolon inside RCU_TRACE() for rcu.h Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 06/40] rcu: Semicolon inside RCU_TRACE() for Tiny RCU Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 07/40] rcu: Semicolon inside RCU_TRACE() for tree.c Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 08/40] rcu: Make call_rcu() do deferred NOCB wakeups Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 09/40] rcu: Make rcu_all_qs() " Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 10/40] rcu: Make rcu_note_context_switch() " Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 11/40] rcu: Pull rcu_sched_qs_mask into rcu_dynticks structure Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 12/40] rcu: Pull rcu_qs_ctr " Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 13/40] rcu: Eliminate flavor scan in rcu_momentary_dyntick_idle() Paul E. McKenney
2017-04-12 17:39 ` [PATCH tip/core/rcu 14/40] rcu: Place guard on rcu_all_qs() and rcu_note_context_switch() actions Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 15/40] rcu: Default RCU_FANOUT_LEAF to 16 unless explicitly changed Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 16/40] srcu: Abstract multi-tail callback list handling Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 17/40] srcu: Allow SRCU to access rcu_scheduler_active Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 18/40] srcu: Allow early boot use of synchronize_srcu() Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 19/40] rcu: Add single-element dequeue functions to rcu_segcblist Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 20/40] srcu: Move rcu_seq_start() and friends to rcu.h Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 21/40] rcu: Expedited wakeups need to be fully ordered Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 22/40] rcu: Fix warning in rcu_seq_end() Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 23/40] srcu: Push srcu_advance_batches() fastpath into common case Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 24/40] srcu: Move to state-based grace-period sequencing Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 25/40] srcu: Add grace-period sequence numbers Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 26/40] srcu: Use rcu_segcblist to track SRCU callbacks Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 27/40] srcu: Move combining-tree definitions for SRCU's benefit Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 28/40] srcu: Move rcu_init_levelspread() to rcu_tree_node.h Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 29/40] rcu: Remove redundant levelcnt[] array from rcu_init_one() Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 30/40] srcu: Move rcu_node traversal macros to rcu.h Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 31/40] srcu: Make num_rcu_lvl[] array be external Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 32/40] srcu: Fix bogus try_check_zero() comment Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 33/40] srcu: Improve rcu_seq grace-period-counter abstraction Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 34/40] srcu: Allow a second bit in rcu_seq for SRCU state Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 35/40] srcu: Merge ->srcu_state into ->srcu_gp_seq Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 36/40] srcu: Crude control of expedited grace periods Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 37/40] srcu: Create a tiny SRCU Paul E. McKenney
2017-04-13  9:48   ` Peter Zijlstra
2017-04-13 16:30     ` Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 38/40] srcutorture: Print Tiny SRCU reader statistics Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 39/40] srcu: Introduce CLASSIC_SRCU Kconfig option Paul E. McKenney
2017-04-12 17:40 ` [PATCH tip/core/rcu 40/40] srcu: Parallelize callback handling Paul E. McKenney
2017-04-13  9:50   ` Peter Zijlstra
2017-04-13 16:37     ` Paul E. McKenney
2017-04-13 17:42       ` Paul E. McKenney
2017-04-13  9:54   ` Peter Zijlstra
2017-04-13 16:50     ` Paul E. McKenney
2017-04-20  3:40   ` powerpc KVM build break in linux-next (was Re: [PATCH tip/core/rcu 40/40] srcu: Parallelize callback handling) Michael Ellerman
2017-04-20 14:19     ` Paul E. McKenney
2017-04-20 15:28     ` Paolo Bonzini
2017-04-21  0:38       ` Paul E. McKenney
2017-04-21  1:42         ` Michael Ellerman
2017-04-21  4:17           ` Paul E. McKenney
2017-04-21  7:27             ` Paolo Bonzini
2017-04-21 12:51               ` Paul E. McKenney
2017-04-22  6:09                 ` Michael Ellerman
2017-04-21  2:13       ` Michael Ellerman
2017-04-17 23:44 ` [PATCH v2 tip/core/rcu 0/40] SRCU callback parallelization for 4.12 Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 01/39] rcu: Maintain special bits at bottom of ->dynticks counter Paul E. McKenney
2017-04-18  0:07     ` Josh Triplett
2017-04-18 18:19       ` Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 02/39] rcu: Make arch select smp_mb__after_unlock_lock() strength Paul E. McKenney
2017-04-18  0:19     ` Josh Triplett
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 03/39] srcu: Consolidate batch checking into rcu_all_batches_empty() Paul E. McKenney
2017-04-18  0:30     ` Josh Triplett
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 04/39] srcu: Check for tardy grace-period activity in cleanup_srcu_struct() Paul E. McKenney
2017-04-18  0:33     ` Josh Triplett
2017-04-18  0:34       ` Josh Triplett
2017-04-18 18:34         ` Paul E. McKenney
2017-04-18 19:44           ` Josh Triplett
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 05/39] rcu: Semicolon inside RCU_TRACE() for rcu.h Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 06/39] rcu: Semicolon inside RCU_TRACE() for Tiny RCU Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 07/39] rcu: Semicolon inside RCU_TRACE() for tree.c Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 08/39] rcu: Pull rcu_sched_qs_mask into rcu_dynticks structure Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 09/39] rcu: Pull rcu_qs_ctr " Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 10/39] rcu: Eliminate flavor scan in rcu_momentary_dyntick_idle() Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 11/39] rcu: Place guard on rcu_all_qs() and rcu_note_context_switch() actions Paul E. McKenney
2017-04-17 23:44   ` [PATCH v2 tip/core/rcu 12/39] rcu: Default RCU_FANOUT_LEAF to 16 unless explicitly changed Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 13/39] srcu: Abstract multi-tail callback list handling Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 14/39] srcu: Allow SRCU to access rcu_scheduler_active Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 15/39] srcu: Allow early boot use of synchronize_srcu() Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 16/39] rcu: Add single-element dequeue functions to rcu_segcblist Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 17/39] srcu: Move rcu_seq_start() and friends to rcu.h Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 18/39] rcu: Expedited wakeups need to be fully ordered Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 19/39] rcu: Fix warning in rcu_seq_end() Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 20/39] srcu: Push srcu_advance_batches() fastpath into common case Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 21/39] srcu: Move to state-based grace-period sequencing Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 22/39] srcu: Add grace-period sequence numbers Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 23/39] srcu: Use rcu_segcblist to track SRCU callbacks Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 24/39] srcu: Move combining-tree definitions for SRCU's benefit Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 25/39] srcu: Move rcu_init_levelspread() to rcu_tree_node.h Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 26/39] rcu: Remove redundant levelcnt[] array from rcu_init_one() Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 27/39] srcu: Move rcu_node traversal macros to rcu.h Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 28/39] srcu: Make num_rcu_lvl[] array be external Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 29/39] srcu: Fix bogus try_check_zero() comment Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 30/39] srcu: Improve rcu_seq grace-period-counter abstraction Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 31/39] srcu: Allow a second bit in rcu_seq for SRCU state Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 32/39] srcu: Merge ->srcu_state into ->srcu_gp_seq Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 33/39] srcu: Crude control of expedited grace periods Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 34/39] mm: Use static initialization for "srcu" Paul E. McKenney
2017-04-17 23:45   ` Paul E. McKenney [this message]
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 36/39] srcutorture: Print Tiny SRCU reader statistics Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 37/39] srcu: Introduce CLASSIC_SRCU Kconfig option Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 38/39] srcu: Parallelize callback handling Paul E. McKenney
2017-04-17 23:45   ` [PATCH v2 tip/core/rcu 39/39] rcu: Make non-preemptive schedule be Tasks RCU quiescent state Paul E. McKenney
2017-04-19 16:58   ` [PATCH v3 tip/core/rcu 0/40] SRCU callback parallelization for 4.12 Paul E. McKenney
2017-04-19 16:57     ` [PATCH v3 tip/core/rcu 01/40] rcu: Maintain special bits at bottom of ->dynticks counter Paul E. McKenney
2017-04-19 16:57     ` [PATCH v3 tip/core/rcu 02/40] rcu: Make arch select smp_mb__after_unlock_lock() strength Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 03/40] srcu: Consolidate batch checking into rcu_all_batches_empty() Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 04/40] srcu: Check for tardy grace-period activity in cleanup_srcu_struct() Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 05/40] rcu: Semicolon inside RCU_TRACE() for rcu.h Paul E. McKenney
2017-04-19 17:41       ` Joe Perches
2017-04-25 21:00         ` Paul E. McKenney
2017-04-25 21:13       ` Steven Rostedt
2017-04-25 21:27         ` Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 06/40] rcu: Semicolon inside RCU_TRACE() for Tiny RCU Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 07/40] rcu: Semicolon inside RCU_TRACE() for tree.c Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 08/40] rcu: Pull rcu_sched_qs_mask into rcu_dynticks structure Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 09/40] rcu: Pull rcu_qs_ctr " Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 10/40] rcu: Eliminate flavor scan in rcu_momentary_dyntick_idle() Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 11/40] rcu: Place guard on rcu_all_qs() and rcu_note_context_switch() actions Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 12/40] rcu: Default RCU_FANOUT_LEAF to 16 unless explicitly changed Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 13/40] srcu: Abstract multi-tail callback list handling Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 14/40] srcu: Allow SRCU to access rcu_scheduler_active Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 15/40] srcu: Allow early boot use of synchronize_srcu() Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 16/40] rcu: Add single-element dequeue functions to rcu_segcblist Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 17/40] srcu: Move rcu_seq_start() and friends to rcu.h Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 18/40] rcu: Expedited wakeups need to be fully ordered Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 19/40] rcu: Fix warning in rcu_seq_end() Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 20/40] srcu: Push srcu_advance_batches() fastpath into common case Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 21/40] srcu: Move to state-based grace-period sequencing Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 22/40] srcu: Add grace-period sequence numbers Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 23/40] srcu: Use rcu_segcblist to track SRCU callbacks Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 24/40] srcu: Move combining-tree definitions for SRCU's benefit Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 25/40] srcu: Move rcu_init_levelspread() to rcu_tree_node.h Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 26/40] rcu: Remove redundant levelcnt[] array from rcu_init_one() Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 27/40] srcu: Move rcu_node traversal macros to rcu.h Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 28/40] srcu: Make num_rcu_lvl[] array be external Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 29/40] srcu: Fix bogus try_check_zero() comment Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 30/40] srcu: Improve rcu_seq grace-period-counter abstraction Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 31/40] srcu: Allow a second bit in rcu_seq for SRCU state Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 32/40] srcu: Merge ->srcu_state into ->srcu_gp_seq Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 33/40] srcu: Crude control of expedited grace periods Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 34/40] mm: Use static initialization for "srcu" Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 35/40] srcu: Create a tiny SRCU Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 36/40] srcutorture: Print Tiny SRCU reader statistics Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 37/40] srcu: Introduce CLASSIC_SRCU Kconfig option Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 38/40] srcu: Parallelize callback handling Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 39/40] srcu: Expedite srcu_schedule_cbs_snp() callback invocation Paul E. McKenney
2017-04-19 16:58     ` [PATCH v3 tip/core/rcu 40/40] rcu: Make non-preemptive schedule be Tasks RCU quiescent state Paul E. McKenney
2017-09-28  9:37       ` Sasha Levin
2017-09-28 12:30         ` Paul E. McKenney
2017-09-28 15:38           ` Levin, Alexander (Sasha Levin)
2017-09-28 16:05             ` Paul E. McKenney
2017-09-28 16:18               ` Peter Zijlstra
2017-09-28 16:30                 ` Paul E. McKenney
2017-09-29  9:30               ` Boqun Feng
2017-09-29 10:01                 ` Paolo Bonzini
2017-09-29 10:25                   ` Boqun Feng
2017-09-29 10:34                   ` Peter Zijlstra
2017-09-29 11:44                     ` Paolo Bonzini
2017-09-29 16:38                       ` Paul E. McKenney
2017-09-29 16:36                   ` Paul E. McKenney
2017-09-28 16:08             ` Peter Zijlstra
2017-09-28 16:23               ` Levin, Alexander (Sasha Levin)

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