Re: [PATCH v2] can: isotp: handle wait_event_interruptible() return values

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 06.01.23 12:37, Marc Kleine-Budde wrote:
> On 05.01.2023 13:58:30, Oliver Hartkopp wrote:
>>
>>
>> On 05.01.23 10:32, Marc Kleine-Budde wrote:
>>> On 04.01.2023 17:46:05, Oliver Hartkopp wrote:
>>>> When wait_event_interruptible() has been interrupted by a signal the
>>>> tx.state value might not be ISOTP_IDLE. Force the state machines
>>>> into idle state to inhibit the timer handlers to continue working.
>>>>
>>>> Cc: stable@vger.kernel.org # >= v5.15
>>>> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
>>>
>>> Can you add a Fixes: tag?
>>
>> Yes. Sent out a V3.
>>
>> In fact I was not sure if it makes sense to apply the patch down to Linux
>> 5.10 as it might increase the possibility to trigger a WARN(1) in the
>> isotp_tx_timer_handler().
>>
>> The patch is definitely helpful for the latest code including commit
>> 4b7fe92c0690 ("can: isotp: add local echo tx processing for consecutive
>> frames") introduced in Linux 5.18 and its fixes.
>>
>> I did some testing with very long ISOTP PDUs and killed the waiting
>> isotp_release() with a Crtl-C.
>>
>> To prevent the WARN(1) we might also stick this patch to
>>
>> Fixes: 866337865f37 ("can: isotp: fix tx state handling for echo tx
>> processing")
>>
>> What do you think about the WARN(1)?
> 
> If this short patch avoids potential WARN()s it's stable material.
> 

It is the other way around. As written above this patch might increase 
the possibility to trigger a WARN(1).

With the patch:

https://lore.kernel.org/linux-can/20230104145701.2422-1-socketcan@hartkopp.net/T/#u

the WARN(1) is removed and this patch here makes the situation better.

Alternatively I could provide another patch for kernels < v6.0 which set 
the rx/tx states AND remove the WARN(1).

Back to your original question about the "Fixes:" tag, I would suggest 
to tag this patch similar to

https://lore.kernel.org/linux-can/20230104145701.2422-1-socketcan@hartkopp.net/T/#u

Namely:

Fixes: 866337865f37 ("can: isotp: fix tx state handling for echo tx 
processing")
Cc: stable@vger.kernel.org # >= v6.0

And later check whether I should remove the WARN(1) in older stable kernels.

Should I send a V4 with the new "Fixes: 866337865f37" tag?

Best regards,
Oliver