diff options
Diffstat (limited to 'nptl/pthread_mutex_timedlock.c')
| -rw-r--r-- | nptl/pthread_mutex_timedlock.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c index 07f0901e52..21e9eeada0 100644 --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -142,13 +142,19 @@ pthread_mutex_timedlock (pthread_mutex_t *mutex, &mutex->__data.__list.__next); oldval = mutex->__data.__lock; + /* This is set to FUTEX_WAITERS iff we might have shared the + FUTEX_WAITERS flag with other threads, and therefore need to keep it + set to avoid lost wake-ups. We have the same requirement in the + simple mutex algorithm. */ + unsigned int assume_other_futex_waiters = 0; do { again: if ((oldval & FUTEX_OWNER_DIED) != 0) { /* The previous owner died. Try locking the mutex. */ - int newval = id | (oldval & FUTEX_WAITERS); + int newval = id | (oldval & FUTEX_WAITERS) + | assume_other_futex_waiters; newval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, @@ -203,8 +209,12 @@ pthread_mutex_timedlock (pthread_mutex_t *mutex, } } - result = lll_robust_timedlock (mutex->__data.__lock, abstime, id, + result = lll_robust_timedlock (mutex->__data.__lock, abstime, + id | assume_other_futex_waiters, PTHREAD_ROBUST_MUTEX_PSHARED (mutex)); + /* See above. We set FUTEX_WAITERS and might have shared this flag + with other threads; thus, we need to preserve it. */ + assume_other_futex_waiters = FUTEX_WAITERS; if (__builtin_expect (mutex->__data.__owner == PTHREAD_MUTEX_NOTRECOVERABLE, 0)) |