linux-kernel - [PATCH 5.3 071/344] rcu: Add destroy_work_on_stack() to match INIT_WORK

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Date:   Thu,  3 Oct 2019 17:50:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrea Arcangeli <aarcange@...hat.com>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.3 071/344] rcu: Add destroy_work_on_stack() to match INIT_WORK_ONSTACK()

From: Paul E. McKenney <paulmck@...ux.ibm.com>

[ Upstream commit fbad01af8c3bb9618848abde8054ab7e0c2330fe ]

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>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 af7e7b9c86afa..513b403b683b7 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);
-- 
2.20.1