linux-kernel - [PATCH tip/core/rcu 05/12] rcu: Add destroy_work_on_stack() to match INIT_WORK

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Message-Id: <20190801223747.15560-5-paulmck@linux.ibm.com>
Date:   Thu,  1 Aug 2019 15:37:40 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 05/12] rcu: Add destroy_work_on_stack() to match INIT_WORK_ONSTACK()

The synchronize_rcu_expedited() function has an INIT_WORK_ONSTACK(),
but lacks the corresponding destroy_work_on_stack().  This commit
therefore adds destroy_work_on_stack().

Reported-by: Andrea Arcangeli <aarcange@...hat.com>
Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.com>
Acked-by: Andrea Arcangeli <aarcange@...hat.com>
---
 kernel/rcu/tree_exp.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index af7e7b9c86af..513b403b683b 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -792,6 +792,7 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp)
  */
 void synchronize_rcu_expedited(void)
 {
+	bool boottime = (rcu_scheduler_active == RCU_SCHEDULER_INIT);
 	struct rcu_exp_work rew;
 	struct rcu_node *rnp;
 	unsigned long s;
@@ -817,7 +818,7 @@ void synchronize_rcu_expedited(void)
 		return;  /* Someone else did our work for us. */
 
 	/* Ensure that load happens before action based on it. */
-	if (unlikely(rcu_scheduler_active == RCU_SCHEDULER_INIT)) {
+	if (unlikely(boottime)) {
 		/* Direct call during scheduler init and early_initcalls(). */
 		rcu_exp_sel_wait_wake(s);
 	} else {
@@ -835,5 +836,8 @@ void synchronize_rcu_expedited(void)
 
 	/* Let the next expedited grace period start. */
 	mutex_unlock(&rcu_state.exp_mutex);
+
+	if (likely(!boottime))
+		destroy_work_on_stack(&rew.rew_work);
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
-- 
2.17.1