diff options
Diffstat (limited to 'nptl/pthread_cond_wait.c')
| -rw-r--r-- | nptl/pthread_cond_wait.c | 57 |
1 files changed, 49 insertions, 8 deletions
diff --git a/nptl/pthread_cond_wait.c b/nptl/pthread_cond_wait.c index 0ae320cb83..01d42d7834 100644 --- a/nptl/pthread_cond_wait.c +++ b/nptl/pthread_cond_wait.c @@ -26,7 +26,6 @@ #include <shlib-compat.h> #include <stap-probe.h> - struct _condvar_cleanup_buffer { int oldtype; @@ -85,8 +84,15 @@ __condvar_cleanup (void *arg) lll_futex_wake (&cbuffer->cond->__data.__futex, INT_MAX, pshared); /* Get the mutex before returning unless asynchronous cancellation - is in effect. */ - __pthread_mutex_cond_lock (cbuffer->mutex); + is in effect. We don't try to get the mutex if we already own it. */ + if (!(USE_REQUEUE_PI (cbuffer->mutex)) + || ((cbuffer->mutex->__data.__lock & FUTEX_TID_MASK) + != THREAD_GETMEM (THREAD_SELF, tid))) + { + __pthread_mutex_cond_lock (cbuffer->mutex); + } + else + __pthread_mutex_cond_lock_adjust (cbuffer->mutex); } @@ -101,6 +107,11 @@ __pthread_cond_wait (cond, mutex) int pshared = (cond->__data.__mutex == (void *) ~0l) ? LLL_SHARED : LLL_PRIVATE; +#if (defined lll_futex_wait_requeue_pi \ + && defined __ASSUME_REQUEUE_PI) + int pi_flag = 0; +#endif + LIBC_PROBE (cond_wait, 2, cond, mutex); /* Make sure we are alone. */ @@ -144,15 +155,36 @@ __pthread_cond_wait (cond, mutex) do { unsigned int futex_val = cond->__data.__futex; - /* Prepare to wait. Release the condvar futex. */ lll_unlock (cond->__data.__lock, pshared); /* Enable asynchronous cancellation. Required by the standard. */ cbuffer.oldtype = __pthread_enable_asynccancel (); - /* Wait until woken by signal or broadcast. */ - lll_futex_wait (&cond->__data.__futex, futex_val, pshared); +#if (defined lll_futex_wait_requeue_pi \ + && defined __ASSUME_REQUEUE_PI) + /* If pi_flag remained 1 then it means that we had the lock and the mutex + but a spurious waker raced ahead of us. Give back the mutex before + going into wait again. */ + if (pi_flag) + { + __pthread_mutex_cond_lock_adjust (mutex); + __pthread_mutex_unlock_usercnt (mutex, 0); + } + pi_flag = USE_REQUEUE_PI (mutex); + + if (pi_flag) + { + err = lll_futex_wait_requeue_pi (&cond->__data.__futex, + futex_val, &mutex->__data.__lock, + pshared); + + pi_flag = (err == 0); + } + else +#endif + /* Wait until woken by signal or broadcast. */ + lll_futex_wait (&cond->__data.__futex, futex_val, pshared); /* Disable asynchronous cancellation. */ __pthread_disable_asynccancel (cbuffer.oldtype); @@ -189,8 +221,17 @@ __pthread_cond_wait (cond, mutex) /* The cancellation handling is back to normal, remove the handler. */ __pthread_cleanup_pop (&buffer, 0); - /* Get the mutex before returning. */ - return __pthread_mutex_cond_lock (mutex); + /* Get the mutex before returning. Not needed for PI. */ +#if (defined lll_futex_wait_requeue_pi \ + && defined __ASSUME_REQUEUE_PI) + if (pi_flag) + { + __pthread_mutex_cond_lock_adjust (mutex); + return 0; + } + else +#endif + return __pthread_mutex_cond_lock (mutex); } versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait, |