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htl: Fix case when sem_*wait is canceled while holding a token 

* sysdeps/htl/sem-timedwait.c (struct cancel_ctx): Add cancel_wake
field.
(cancel_hook): When unblocking thread, set cancel_wake field to 1.
(__sem_timedwait_internal): Set cancel_wake field to 0 by default.
On cancellation exit, check whether we hold a token, to be put back.
This commit is contained in:
Samuel Thibault 2020-06-24 00:18:45 +00:00
parent eca16db02d
commit 1b90d52df9
1 changed files with 13 additions and 2 deletions
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11
sysdeps/htl/sem-timedwait.c
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@ -27,6 +27,7 @@ struct cancel_ctx
{
struct __pthread *wakeup;
sem_t *sem;
int cancel_wake;
};
static void
@ -42,7 +43,10 @@ cancel_hook (void *arg)
If it was already unblocked, it's not queued any more. */
unblock = wakeup->prevp != NULL;
if (unblock)
{
__pthread_dequeue (wakeup);
ctx->cancel_wake = 1;
}
__pthread_spin_unlock (&sem->__lock);
if (unblock)
@ -62,6 +66,7 @@ __sem_timedwait_internal (sem_t *restrict sem,
struct cancel_ctx ctx;
ctx.wakeup = self;
ctx.sem = sem;
ctx.cancel_wake = 0;
/* Test for a pending cancellation request, switch to deferred mode for
safer resource handling, and prepare the hook to call in case we're
@ -159,7 +164,13 @@ out_locked:
__pthread_mutex_unlock (&self->cancel_lock);
if (cancelled)
{
if (ret == 0 && ctx.cancel_wake == 0)
/* We were cancelled while waking up with a token, put it back. */
sem_post (sem);
__pthread_exit (PTHREAD_CANCELED);
}
return ret;
}