linux-kernel - Re: [PATCH v3 4/7] rcu: handle unstable rdp in rcu_read_unlock

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Message-ID: <Z1w47BFWBVIHWFeD@localhost.localdomain>
Date: Fri, 13 Dec 2024 14:38:52 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: Ankur Arora <ankur.a.arora@...cle.com>
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org, tglx@...utronix.de,
	paulmck@...nel.org, mingo@...nel.org, bigeasy@...utronix.de,
	juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, efault@....de,
	sshegde@...ux.ibm.com, boris.ostrovsky@...cle.com
Subject: Re: [PATCH v3 4/7] rcu: handle unstable rdp in
 rcu_read_unlock_strict()

Le Thu, Dec 12, 2024 at 08:06:55PM -0800, Ankur Arora a écrit :
> rcu_read_unlock_strict() can be called with preemption enabled
> which can make for an unstable rdp and a racy norm value.
> 
> Fix this by dropping the preempt-count in __rcu_read_unlock()
> after the call to rcu_read_unlock_strict(), adjusting the
> preempt-count check appropriately.
> 
> Suggested-by: Frederic Weisbecker <frederic@...nel.org>
> Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>

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