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2007-05-07 Ulrich Drepper <drepper@redhat.com>

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* sysdeps/unix/sysv/linux/lowlevelrobustlock.c
	(__lll_robust_lock_wait): Fix race caused by reloading of futex value.
	(__lll_robust_timedlock_wait): Likewise.
	Reported by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>.
This commit is contained in:
Jakub Jelinek 2007-07-12 15:21:44 +00:00
parent 05b4aead80
commit 8e644efe5e
2 changed files with 25 additions and 2 deletions
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7
nptl/ChangeLog
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@ -1,3 +1,10 @@
2007-05-07 Ulrich Drepper <drepper@redhat.com>
* sysdeps/unix/sysv/linux/lowlevelrobustlock.c
(__lll_robust_lock_wait): Fix race caused by reloading of futex value.
(__lll_robust_timedlock_wait): Likewise.
Reported by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>.
2007-05-06 Mike Frysinger <vapier@gentoo.org>
[BZ #4465]

20
nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c
View File

@ -30,6 +30,10 @@ __lll_robust_lock_wait (int *futex)
int oldval = *futex;
int tid = THREAD_GETMEM (THREAD_SELF, tid);
/* If the futex changed meanwhile try locking again. */
if (oldval == 0)
goto try;
do
{
if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
@ -41,6 +45,9 @@ __lll_robust_lock_wait (int *futex)
continue;
lll_futex_wait (futex, newval);
try:
;
}
while ((oldval = atomic_compare_and_exchange_val_acq (futex,
tid | FUTEX_WAITERS,
@ -57,6 +64,11 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime)
return EINVAL;
int tid = THREAD_GETMEM (THREAD_SELF, tid);
int oldval = *futex;
/* If the futex changed meanwhile try locking again. */
if (oldval == 0)
goto try;
do
{
@ -80,7 +92,6 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime)
return ETIMEDOUT;
/* Wait. */
int oldval = *futex;
if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
return oldval;
@ -90,8 +101,13 @@ __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime)
continue;
lll_futex_timed_wait (futex, newval, &rt);
try:
;
}
while (atomic_compare_and_exchange_bool_acq (futex, tid | FUTEX_WAITERS, 0));
while ((oldval = atomic_compare_and_exchange_val_acq (futex,
tid | FUTEX_WAITERS,
0)) != 0);
return 0;
}