Re: [PATCH RT 1/2] tasklet: Address a race resulting in double-enqueue

On June 9, 2020 7:34:46 PM GMT+03:00, Sebastian Andrzej Siewior [off-list ref] wrote:

On 2020-06-09 11:17:53 [-0500], Tom Zanussi wrote:

quoted

Hi Sebastian,

Hi Tom,

quoted

I did find a problem with the patch when configured as !SMP since in
that case the RUN flag is never set (will send a patch for that
shortly), but that wouldn't be the case here.

How?

| #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT_FULL)
| static inline int tasklet_trylock(struct tasklet_struct *t)
| {
|         return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
| }

I can't tell from the backtrace if he runs with RT or without but I
assumed RT. But yes, for !SMP && !RT it would explain it.

PREEMT_FULL is enabled. 
I'm working on getting symbols for this trace, this is a crash kernel so everything is stripped naked. 
Thanks, Ramon

quoted

It would help to be able to reproduce it, but I haven't been able to
yet.

Tom

Sebastian

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.