There are deadlocks caused by del_timer_sync(&priv->hang_timer) and
del_timer_sync(&priv->rr_timer) in grcan_close(), one of the deadlocks
are shown below:
(Thread 1) | (Thread 2)
| grcan_reset_timer()
grcan_close() | mod_timer()
spin_lock_irqsave() //(1) | (wait a time)
... | grcan_initiate_running_reset()
del_timer_sync() | spin_lock_irqsave() //(2)
(wait timer to stop) | ...
We hold priv->lock in position (1) of thread 1 and use
del_timer_sync() to wait timer to stop, but timer handler also need
priv->lock in position (2) of thread 2. As a result, grcan_close()
will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_irqsave(), which could let timer handler to obtain the
needed lock.
Link: https://lore.kernel.org/all/20220425042400.66517-1-duoming@zju.edu.cn
Fixes: 6cec9b07fe ("can: grcan: Add device driver for GRCAN and GRHCAN cores")
Cc: stable@vger.kernel.org
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
47f070a63e