[FFmpeg-cvslog] w32threads: wait for the waked thread in pthread_cond_signal.
Sergey Radionov
git at videolan.org
Thu Dec 22 02:05:03 CET 2011
ffmpeg | branch: master | Sergey Radionov <RSATom at gmail.com> | Wed Dec 21 09:08:56 2011 +0700| [2003a29284660255016b1ec4bd5dfb8d53e6a852] | committer: Ronald S. Bultje
w32threads: wait for the waked thread in pthread_cond_signal.
This fixes a deadlock VLC triggered with multithreaded decoding. The
wait forces one of the current waiters to wake and not the thread
which calls pthread_cond_signal() itself.
Signed-off-by: Ronald S. Bultje <rsbultje at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2003a29284660255016b1ec4bd5dfb8d53e6a852
---
libavcodec/w32pthreads.h | 16 +++++++++++-----
1 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/libavcodec/w32pthreads.h b/libavcodec/w32pthreads.h
index 2d1470c..3cdbc2c 100644
--- a/libavcodec/w32pthreads.h
+++ b/libavcodec/w32pthreads.h
@@ -139,7 +139,7 @@ static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
if (!win32_cond->semaphore)
return;
- win32_cond->waiters_done = CreateEvent(NULL, FALSE, FALSE, NULL);
+ win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
if (!win32_cond->waiters_done)
return;
@@ -204,11 +204,10 @@ static void pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
/* non native condition variables */
pthread_mutex_lock(&win32_cond->mtx_broadcast);
- pthread_mutex_unlock(&win32_cond->mtx_broadcast);
-
pthread_mutex_lock(&win32_cond->mtx_waiter_count);
win32_cond->waiter_count++;
pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
+ pthread_mutex_unlock(&win32_cond->mtx_broadcast);
// unlock the external mutex
pthread_mutex_unlock(mutex);
@@ -216,7 +215,7 @@ static void pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
pthread_mutex_lock(&win32_cond->mtx_waiter_count);
win32_cond->waiter_count--;
- last_waiter = !win32_cond->waiter_count && win32_cond->is_broadcast;
+ last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
if (last_waiter)
@@ -235,13 +234,20 @@ static void pthread_cond_signal(pthread_cond_t *cond)
return;
}
+ pthread_mutex_lock(&win32_cond->mtx_broadcast);
+
/* non-native condition variables */
pthread_mutex_lock(&win32_cond->mtx_waiter_count);
have_waiter = win32_cond->waiter_count;
pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
- if (have_waiter)
+ if (have_waiter) {
ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
+ WaitForSingleObject(win32_cond->waiters_done, INFINITE);
+ ResetEvent(win32_cond->waiters_done);
+ }
+
+ pthread_mutex_unlock(&win32_cond->mtx_broadcast);
}
static void w32thread_init(void)
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