linux-kernel - [PATCH tip/core/rcu 2/3] rcu: Add missing annotation for exit_tasks_rcu

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Message-Id: <20200215002520.15746-2-paulmck@kernel.org>
Date:   Fri, 14 Feb 2020 16:25:19 -0800
From:   paulmck@...nel.org
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com, 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,
        Jules Irenge <jbi.octave@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH tip/core/rcu 2/3] rcu: Add missing annotation for exit_tasks_rcu_start()

From: Jules Irenge <jbi.octave@...il.com>

Sparse reports a warning at exit_tasks_rcu_start(void)

|warning: context imbalance in exit_tasks_rcu_start() - wrong count at exit

To fix this, this commit adds an __acquires(&tasks_rcu_exit_srcu).
Given that exit_tasks_rcu_start() does actually call __srcu_read_lock(),
this not only fixes the warning but also improves on the readability of
the code.

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/update.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index a27df76..a04fe54 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -801,7 +801,7 @@ static int __init rcu_spawn_tasks_kthread(void)
 core_initcall(rcu_spawn_tasks_kthread);
 
 /* Do the srcu_read_lock() for the above synchronize_srcu().  */
-void exit_tasks_rcu_start(void)
+void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu)
 {
 	preempt_disable();
 	current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
-- 
2.9.5