[PATCH] can: softing: Fix locking in softing_card_shutdown()

[PATCH] can: softing: Fix locking in softing_card_shutdown()

[Bart Van Assche]

If mutex_lock_interruptible() fails, softing_card_shutdown() goes on
without holding card->fw.lock and later unlocks that mutex anyway.
Shutting down cannot fail, so use mutex_lock() instead. This makes
sure the firmware state is always changed with fw.lock held and that
only a held mutex is unlocked.

Fixes: 03fd3cf5a179 ("can: add driver for Softing card")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/net/can/softing/softing_main.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/can/softing/softing_main.c b/drivers/net/can/softing/softing_main.c
index 519ab3097f86..d3dfad4f5321 100644
--- a/drivers/net/can/softing/softing_main.c
+++ b/drivers/net/can/softing/softing_main.c
@@ -448,9 +448,7 @@ static void softing_card_shutdown(struct softing *card)
 {
 	int fw_up = 0;
 
-	if (mutex_lock_interruptible(&card->fw.lock)) {
-		/* return -ERESTARTSYS */;
-	}
+	mutex_lock(&card->fw.lock);
 	fw_up = card->fw.up;
 	card->fw.up = 0;
 

Re: [PATCH] can: softing: Fix locking in softing_card_shutdown()

[Marc Kleine-Budde]

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Hello Bart,

thanks for you contribution.

On 26.10.2026 12:47:07, Bart Van Assche wrote:
> If mutex_lock_interruptible() fails, softing_card_shutdown() goes on
> without holding card->fw.lock and later unlocks that mutex anyway.
> Shutting down cannot fail, so use mutex_lock() instead. This makes
> sure the firmware state is always changed with fw.lock held and that
> only a held mutex is unlocked.
>
> Fixes: 03fd3cf5a179 ("can: add driver for Softing card")
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Are you actively using this driver? It's scheduled for removal in the
v7.15.

regards,
Marc

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Re: [PATCH] can: softing: Fix locking in softing_card_shutdown()

[Bart Van Assche]

On 10/26/26 1:14 PM, Marc Kleine-Budde wrote:
> Are you actively using this driver? It's scheduled for removal in the
> v7.15.
I'm not using the driver. I'm working on fixing all locking bugs across
the entire kernel tree. Removing this driver will also make the locking
bug disappear :-)

Thanks,

Bart.