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author | Ulrich Drepper <drepper@redhat.com> | 2004-02-19 04:10:16 +0000 |
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committer | Ulrich Drepper <drepper@redhat.com> | 2004-02-19 04:10:16 +0000 |
commit | 37c054c7c4a969816d2bc3c8284bdcadf68ebeec (patch) | |
tree | ec0a8cc53830ddb66445be30615fd15b894495fa /nptl/sysdeps/pthread/pthread_barrier_wait.c | |
parent | dc39124662b25ce2db28454f1749d67550e4de31 (diff) | |
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Update.
* sysdeps/unix/sysv/linux/i386/i486/pthread_barrier_wait.S
(pthread_barrier_wait): After wakeup, release lock only when the
last thread stopped using the barrier object.
* sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S
(pthread_barrier_wait): Likewise.
* sysdeps/pthread/pthread_barrier_wait.c (pthread_barrier_wait):
Likewise.
* Makefile (tests): Add tst-barrier4.
* tst-barrier4.c: New file.
Diffstat (limited to 'nptl/sysdeps/pthread/pthread_barrier_wait.c')
-rw-r--r-- | nptl/sysdeps/pthread/pthread_barrier_wait.c | 54 |
1 files changed, 28 insertions, 26 deletions
diff --git a/nptl/sysdeps/pthread/pthread_barrier_wait.c b/nptl/sysdeps/pthread/pthread_barrier_wait.c index 69274d6d64..f6dc3e5f16 100644 --- a/nptl/sysdeps/pthread/pthread_barrier_wait.c +++ b/nptl/sysdeps/pthread/pthread_barrier_wait.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2003 Free Software Foundation, Inc. +/* Copyright (C) 2003, 2004 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003. @@ -29,6 +29,7 @@ pthread_barrier_wait (barrier) pthread_barrier_t *barrier; { struct pthread_barrier *ibarrier = (struct pthread_barrier *) barrier; + int result = 0; /* Make sure we are alone. */ lll_lock (ibarrier->lock); @@ -39,41 +40,42 @@ pthread_barrier_wait (barrier) /* Are these all? */ if (ibarrier->left == 0) { - /* Yes. Restore the barrier to be empty. */ - ibarrier->left = ibarrier->init_count; - - /* Increment the event counter to avoid invalid wake-ups and + /* Yes. Increment the event counter to avoid invalid wake-ups and tell the current waiters that it is their turn. */ ++ibarrier->curr_event; /* Wake up everybody. */ lll_futex_wake (&ibarrier->curr_event, INT_MAX); - /* The barrier is open for business again. */ - lll_unlock (ibarrier->lock); - /* This is the thread which finished the serialization. */ - return PTHREAD_BARRIER_SERIAL_THREAD; + result = PTHREAD_BARRIER_SERIAL_THREAD; } - - /* The number of the event we are waiting for. The barrier's event - number must be bumped before we continue. */ - unsigned int event = ibarrier->curr_event; - do + else { - /* Before suspending, make the barrier available to others. */ - lll_unlock (ibarrier->lock); - - /* Wait for the event counter of the barrier to change. */ - lll_futex_wait (&ibarrier->curr_event, event); - - /* We are going to access shared data. */ - lll_lock (ibarrier->lock); + /* The number of the event we are waiting for. The barrier's event + number must be bumped before we continue. */ + unsigned int event = ibarrier->curr_event; + do + { + /* Before suspending, make the barrier available to others. */ + lll_unlock (ibarrier->lock); + + /* Wait for the event counter of the barrier to change. */ + lll_futex_wait (&ibarrier->curr_event, event); + + /* We are going to access shared data. */ + lll_lock (ibarrier->lock); + } + while (event == ibarrier->curr_event); } - while (event == ibarrier->curr_event); - /* We are done, let others use the barrier. */ - lll_unlock (ibarrier->lock); + /* Make sure the init_count is stored locally or in a register. */ + unsigned int init_count = ibarrier->init_count; + + /* If this was the last woken thread, unlock. */ + if (atomic_exchange_and_add (ibarrier->left, 1) == init_count - 1) + /* We are done. */ + lll_unlock (ibarrier->lock); - return 0; + return result; } |