diff options
Diffstat (limited to 'nptl/pthread_once.c')
| -rw-r--r-- | nptl/pthread_once.c | 29 |
1 files changed, 22 insertions, 7 deletions
diff --git a/nptl/pthread_once.c b/nptl/pthread_once.c index 595bd7e298..05aea84d38 100644 --- a/nptl/pthread_once.c +++ b/nptl/pthread_once.c @@ -58,11 +58,13 @@ clear_once_control (void *arg) initialization is interrupted, we then fork 2^30 times (30 bits of once_control are used for the fork generation), and try to initialize again, we can deadlock because we can't distinguish the in-progress and - interrupted cases anymore. */ -int -__pthread_once (once_control, init_routine) - pthread_once_t *once_control; - void (*init_routine) (void); + interrupted cases anymore. + XXX: We split out this slow path because current compilers do not generate + as efficient code when the fast path in __pthread_once below is not in a + separate function. */ +static int +__attribute__ ((noinline)) +__pthread_once_slow (pthread_once_t *once_control, void (*init_routine) (void)) { while (1) { @@ -72,7 +74,7 @@ __pthread_once (once_control, init_routine) signals that initialization has finished, we need to see any data modifications done during initialization. */ val = *once_control; - atomic_read_barrier(); + atomic_read_barrier (); do { /* Check if the initialization has already been done. */ @@ -120,7 +122,7 @@ __pthread_once (once_control, init_routine) /* Mark *once_control as having finished the initialization. We need release memory order here because we need to synchronize with other threads that want to use the initialized data. */ - atomic_write_barrier(); + atomic_write_barrier (); *once_control = __PTHREAD_ONCE_DONE; /* Wake up all other threads. */ @@ -130,5 +132,18 @@ __pthread_once (once_control, init_routine) return 0; } + +int +__pthread_once (pthread_once_t *once_control, void (*init_routine) (void)) +{ + /* Fast path. See __pthread_once_slow. */ + int val; + val = *once_control; + atomic_read_barrier (); + if (__glibc_likely ((val & __PTHREAD_ONCE_DONE) != 0)) + return 0; + else + return __pthread_once_slow (once_control, init_routine); +} weak_alias (__pthread_once, pthread_once) hidden_def (__pthread_once) |