linux-kernel - Re: [patch 04/15] timers: Get rid of del_singleshot_timer

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Message-ID: <20221121150833.61ab3b01@gandalf.local.home>
Date:   Mon, 21 Nov 2022 15:08:33 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Anna-Maria Behnsen <anna-maria@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Arnd Bergmann <arnd@...db.de>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-bluetooth@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [patch 04/15] timers: Get rid of del_singleshot_timer_sync()

On Tue, 15 Nov 2022 21:28:39 +0100 (CET)
Thomas Gleixner <tglx@...utronix.de> wrote:

> del_singleshot_timer_sync() used to be an optimization for deleting timers
> which are not rearmed from the timer callback function.
> 
> This optimization turned out to be broken and got mapped to
> del_timer_sync() about 17 years ago.
> 
> Get rid of the undocumented indirection and use del_timer_sync() directly.
> 
> No functional change.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
>


> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -1164,7 +1164,7 @@ xprt_request_enqueue_receive(struct rpc_
>  	spin_unlock(&xprt->queue_lock);
>  
>  	/* Turn off autodisconnect */
> -	del_singleshot_timer_sync(&xprt->timer);
> +	del_timer_sync(&xprt->timer);

And this was not even a single shot timer. It used the
del_singleshot_timer_sync() function because of incorrect assumptions.

Link: https://lore.kernel.org/all/20221105060155.047357452@goodmis.org/

  0f9dc2b16884b ("RPC: Clean up socket autodisconnect")
  55c888d6d09a0 ("timers fixes/improvements")

Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>

-- Steve


>  	return 0;
>  }
>