From 1b90d52df96c4f768570e148c33bc9c2db53373d Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Wed, 24 Jun 2020 00:18:45 +0000 Subject: 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. --- sysdeps/htl/sem-timedwait.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'sysdeps/htl') diff --git a/sysdeps/htl/sem-timedwait.c b/sysdeps/htl/sem-timedwait.c index 691fb7e5ee..fffdf36467 100644 --- a/sysdeps/htl/sem-timedwait.c +++ b/sysdeps/htl/sem-timedwait.c @@ -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); + { + __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) - __pthread_exit (PTHREAD_CANCELED); + { + 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; } -- cgit v1.2.3-70-g09d2