linux-kernel - [PATCH tip/core/rcu 08/22] rcu: Move rcu_barrier_completion to rcu

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Date:	Fri, 22 Jun 2012 08:17:07 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu, patches@...aro.org,
	"Paul E. McKenney" <paul.mckenney@...aro.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 08/22] rcu: Move rcu_barrier_completion to rcu_state structure

From: "Paul E. McKenney" <paul.mckenney@...aro.org>

In order to allow each RCU flavor to concurrently execute its
rcu_barrier() function, it is necessary to move the relevant
state to the rcu_state structure.  This commit therefore moves the
rcu_barrier_completion global variable to a new ->barrier_completion
field in the rcu_state structure.

Signed-off-by: Paul E. McKenney <paul.mckenney@...aro.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@...htriplett.org>
---
 kernel/rcutree.c |    9 ++++-----
 kernel/rcutree.h |    1 +
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 592c43f..5e087f9 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -158,7 +158,6 @@ unsigned long rcutorture_vernum;
 /* State information for rcu_barrier() and friends. */
 
 static DEFINE_MUTEX(rcu_barrier_mutex);
-static struct completion rcu_barrier_completion;
 
 /*
  * Return true if an RCU grace period is in progress.  The ACCESS_ONCE()s
@@ -2272,7 +2271,7 @@ static void rcu_barrier_callback(struct rcu_head *rhp)
 	struct rcu_state *rsp = rdp->rsp;
 
 	if (atomic_dec_and_test(&rsp->barrier_cpu_count))
-		complete(&rcu_barrier_completion);
+		complete(&rsp->barrier_completion);
 }
 
 /*
@@ -2322,7 +2321,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
 	 * 6.	Both rcu_barrier_callback() callbacks are invoked, awakening
 	 *	us -- but before CPU 1's orphaned callbacks are invoked!!!
 	 */
-	init_completion(&rcu_barrier_completion);
+	init_completion(&rsp->barrier_completion);
 	atomic_set(&rsp->barrier_cpu_count, 1);
 	raw_spin_lock_irqsave(&rsp->onofflock, flags);
 	rsp->rcu_barrier_in_progress = current;
@@ -2372,10 +2371,10 @@ static void _rcu_barrier(struct rcu_state *rsp)
 	 * CPU, and thus each counted, remove the initial count.
 	 */
 	if (atomic_dec_and_test(&rsp->barrier_cpu_count))
-		complete(&rcu_barrier_completion);
+		complete(&rsp->barrier_completion);
 
 	/* Wait for all rcu_barrier_callback() callbacks to be invoked. */
-	wait_for_completion(&rcu_barrier_completion);
+	wait_for_completion(&rsp->barrier_completion);
 
 	/* Other rcu_barrier() invocations can now safely proceed. */
 	mutex_unlock(&rcu_barrier_mutex);
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index e7d29b7..56fb8d4 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -387,6 +387,7 @@ struct rcu_state {
 						/* Task doing rcu_barrier(), */
 						/*  or NULL if no barrier. */
 	atomic_t barrier_cpu_count;		/* # CPUs waiting on. */
+	struct completion barrier_completion;	/* Wake at barrier end. */
 	raw_spinlock_t fqslock;			/* Only one task forcing */
 						/*  quiescent states. */
 	unsigned long jiffies_force_qs;		/* Time at which to invoke */
-- 
1.7.8

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