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[hurd, commited] htl: Fix case when sem_*wait is canceled while holding
From: |
Samuel Thibault |
Subject: |
[hurd, commited] htl: Fix case when sem_*wait is canceled while holding a token |
Date: |
Wed, 24 Jun 2020 02:21:40 +0200 |
* 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(-)
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;
}
--
2.27.0
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Samuel Thibault <=