linux-kernel - [PATCH 2/5] rcu: Add missing annotation for exit_tasks_rcu

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Message-Id: <20200120224126.51615-1-jbi.octave@gmail.com>
Date:   Mon, 20 Jan 2020 22:41:26 +0000
From:   Jules Irenge <jbi.octave@...il.com>
To:     paulmck@...nel.org
Cc:     rostedt@...dmis.org, mathieu.desnoyers@...icios.com,
        joel@...lfernandes.org, rcu@...r.kernel.org, iangshanlai@...il.com,
        boqun.feng@...il.com, linux-kernel@...r.kernel.org,
        Jules Irenge <jbi.octave@...il.com>
Subject: [PATCH 2/5] rcu: Add missing annotation for exit_tasks_rcu_start()

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, an __acquires(&tasks_rcu_exit_srcu) is added.
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>
---
 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 1861103662db..99f4e617116b 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);
-- 
2.24.1