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Date:   Fri, 16 Sep 2022 14:51:39 +0200
From:   Frederic Weisbecker <frederic@kernel.org>
To:     "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc:     linux-kernel@vger.kernel.org,
        Josh Triplett <josh@joshtriplett.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Neeraj Upadhyay <quic_neeraju@quicinc.com>,
        "Paul E. McKenney" <paulmck@kernel.org>, rcu@vger.kernel.org,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH rcu/next 3/3] rcu: Fix late wakeup when flush of bypass
 cblist happens
Message-ID: <20220916125139.GA25891@lothringen>
References: <20220915001419.55617-1-joel@joelfernandes.org>
 <20220915001419.55617-4-joel@joelfernandes.org>
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On Thu, Sep 15, 2022 at 12:14:19AM +0000, Joel Fernandes (Google) wrote:
> When the bypass cblist gets too big or its timeout has occurred, it is
> flushed into the main cblist. However, the bypass timer is still running
> and the behavior is that it would eventually expire and wake the GP
> thread.
> 
> Since we are going to use the bypass cblist for lazy CBs, do the wakeup
> soon as the flush happens. Otherwise, the lazy-timer will go off much
> later and the now-non-lazy cblist CBs can get stranded for the duration
> of the timer.
> 
> This is a good thing to do anyway, since it makes the behavior consistent with
> behavior of other code paths where queueing something into the ->cblist makes
> the GP kthread in a non-sleeping state quickly.
> 
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>