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From:   Zqiang <qiang1.zhang@intel.com>
To:     paulmck@kernel.org, frederic@kernel.org
Cc:     linux-kernel@vger.kernel.org, qiang1.zhang@intel.com
Subject: [PATCH] rcu: When rcuog kthreads is in polling mode, wakeup waitqueue is not requried
Date:   Fri, 28 Jan 2022 11:13:46 +0800
Message-Id: <20220128031346.157961-1-qiang1.zhang@intel.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@intel.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