linux-kernel - Re: [PATCH rcu 1/3] srcu: Remove smp_mb() from srcu_read_unlock

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Message-ID: <e91e70ad-5f30-4b90-9877-7a2dd46375e1@amd.com>
Date: Tue, 12 Nov 2024 08:47:29 +0530
From: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
To: "Paul E. McKenney" <paulmck@...nel.org>, rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel-team@...a.com, rostedt@...dmis.org,
 frederic@...nel.org
Subject: Re: [PATCH rcu 1/3] srcu: Remove smp_mb() from
 srcu_read_unlock_lite()

On 11/12/2024 7:01 AM, Paul E. McKenney wrote:
> The srcu_read_unlock_lite() function invokes __srcu_read_unlock() instead
> of __srcu_read_unlock_lite(), which means that it is doing an unnecessary
> smp_mb().  This is harmless other than the performance degradation.
> 
> This commit therefore switches to __srcu_read_unlock_lite().
> 
> Reported-by: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
> Closes: https://lore.kernel.org/all/d07e8f4a-d5ff-4c8e-8e61-50db285c57e9@amd.com/
> Fixes: c0f08d6b5a61 ("srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite()")
> Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> Cc: Frederic Weisbecker <frederic@...nel.org>
> ---

Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@....com>

- Neeraj