netdev - Re: [PATCH] can: j1939: deactivate session upon receiving the second rts

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Message-ID: <aWdtS3_i0VQLImax@pengutronix.de>
Date: Wed, 14 Jan 2026 11:17:47 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc: Robin van der Gracht <robin@...tonic.nl>, kernel@...gutronix.de,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Marc Kleine-Budde <mkl@...gutronix.de>, linux-can@...r.kernel.org,
	Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH] can: j1939: deactivate session upon receiving the second
 rts

On Wed, Jan 14, 2026 at 12:28:47AM +0900, Tetsuo Handa wrote:
> Since j1939_session_deactivate_activate_next() in j1939_tp_rxtimer() is
> called only when the timer is enabled, we need to call
> j1939_session_deactivate_activate_next() if we cancelled the timer.
> Otherwise, refcount for j1939_session leaks, which will later appear as
> 
>   unregister_netdevice: waiting for vcan0 to become free. Usage count = 2.
> 
> problem.
> 
> Reported-by: syzbot <syzbot+881d65229ca4f9ae8c84@...kaller.appspotmail.com>
> Closes: https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84
> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>

Tested-by: Oleksij Rempel <o.rempel@...gutronix.de>
Acked-by: Oleksij Rempel <o.rempel@...gutronix.de>

Thank you!

Best Regards,
Oleksij
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