* misc/tst-bz21269 hang on i386
@ 2021-07-09 9:37 Florian Weimer
2021-07-09 12:51 ` Adhemerval Zanella
0 siblings, 1 reply; 2+ messages in thread
From: Florian Weimer @ 2021-07-09 9:37 UTC (permalink / raw)
To: libc-alpha
Thread 1 is spinning in do_test, on line 219
214 asm volatile ("mov %0, %%ss" : : "r" (0x7));
215
216 /* Fire up thread modify_ldt call. */
217 atomic_store (&ftx, 2);
218
219 while (atomic_load (&ftx) != 0)
220 ;
And thread 2 appears to be stuck in the FUTEX_WAIT. ftx has the value
2.
I think this happens if threadproc observes ftx == 1, but the FUTEX_WAKE
has already happened, so the FUTEX_WAIT blocks indefinitely.
Is there a reason why the test doesn't use a proper barrier
for synchronization?
Thanks,
Florian
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: misc/tst-bz21269 hang on i386
2021-07-09 9:37 misc/tst-bz21269 hang on i386 Florian Weimer
@ 2021-07-09 12:51 ` Adhemerval Zanella
0 siblings, 0 replies; 2+ messages in thread
From: Adhemerval Zanella @ 2021-07-09 12:51 UTC (permalink / raw)
To: Florian Weimer, libc-alpha
On 09/07/2021 06:37, Florian Weimer wrote:
>
> Thread 1 is spinning in do_test, on line 219
>
> 214 asm volatile ("mov %0, %%ss" : : "r" (0x7));
> 215
> 216 /* Fire up thread modify_ldt call. */
> 217 atomic_store (&ftx, 2);
> 218
> 219 while (atomic_load (&ftx) != 0)
> 220 ;
>
> And thread 2 appears to be stuck in the FUTEX_WAIT. ftx has the value
> 2.
>
> I think this happens if threadproc observes ftx == 1, but the FUTEX_WAKE
> has already happened, so the FUTEX_WAIT blocks indefinitely.
>
> Is there a reason why the test doesn't use a proper barrier
> for synchronization?
I tried to be as close as possible to the kernel test that tries to
trigger the sigaction issue. I proper barrier does make sense here.
^ permalink raw reply [flat|nested] 2+ messages in thread
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