linux-kernel - [PATCH] rcu-tasks: Check the atomic variable trc_n_readers_need

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Message-Id: <20220330112014.2587148-1-qiang1.zhang@intel.com>
Date:   Wed, 30 Mar 2022 19:20:14 +0800
From:   Zqiang <qiang1.zhang@...el.com>
To:     paulmck@...nel.org, frederic@...nel.org
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] rcu-tasks: Check the atomic variable trc_n_readers_need_end again when wait timeout

When the trc_wait waitqueue timeout, the atomic variable
trc_n_readers_need_end need to be checked again, perhaps the
conditions have been established at this time, avoid invalid
stall information output.

Signed-off-by: Zqiang <qiang1.zhang@...el.com>
---
 kernel/rcu/tasks.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 65d6e21a607a..b73a2b362d6b 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1544,7 +1544,7 @@ static void rcu_tasks_trace_postgp(struct rcu_tasks *rtp)
 				trc_wait,
 				atomic_read(&trc_n_readers_need_end) == 0,
 				READ_ONCE(rcu_task_stall_timeout));
-		if (ret)
+		if (ret || !atomic_read(&trc_n_readers_need_end))
 			break;  // Count reached zero.
 		// Stall warning time, so make a list of the offenders.
 		rcu_read_lock();
-- 
2.25.1