linux-kernel - [PATCH] rcu: When rcuog kthreads is in polling mode, wakeup waitqueue is not requried

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Message-Id: <20220128031346.157961-1-qiang1.zhang@intel.com>
Date:   Fri, 28 Jan 2022 11:13:46 +0800
From:   Zqiang <qiang1.zhang@...el.com>
To:     paulmck@...nel.org, frederic@...nel.org
Cc:     linux-kernel@...r.kernel.org, qiang1.zhang@...el.com
Subject: [PATCH] rcu: When rcuog kthreads is in polling mode, wakeup waitqueue is not requried

When grace period cleanup, the rcuog kthreads that waiting in sq
waitqueue will be awakened, however if the 'rcu_nocb_poll' is set,
the sq waitqueue always empty, so if 'rcu_nocb_poll' is set, return
directly.

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

diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 636d0546a4e9..9e106c590e56 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -201,6 +201,8 @@ static void rcu_lockdep_assert_cblist_protected(struct rcu_data *rdp)
  */
 static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq)
 {
+	if (rcu_nocb_poll)
+		return;
 	swake_up_all(sq);
 }
 
-- 
2.25.1