[FFmpeg-cvslog] lavfi: fix race when func rets holder is NULL
Clément Bœsch
git at videolan.org
Wed Mar 29 00:48:08 EEST 2017
ffmpeg | branch: master | Clément Bœsch <cboesch at gopro.com> | Tue Mar 28 18:00:02 2017 +0200| [473f0f75a16b4d37bdaa943f75e4ae249212c1ba] | committer: Clément Bœsch
lavfi: fix race when func rets holder is NULL
If ret is NULL, a dummy common holder is created to hold *all* the
parallel function returns, which gets written concurrently. This commit
simplify the whole logic by simply not writing to that holder when not
set.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=473f0f75a16b4d37bdaa943f75e4ae249212c1ba
---
libavfilter/pthread.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/libavfilter/pthread.c b/libavfilter/pthread.c
index ccb915e..c7a0021 100644
--- a/libavfilter/pthread.c
+++ b/libavfilter/pthread.c
@@ -43,7 +43,6 @@ typedef struct ThreadContext {
AVFilterContext *ctx;
void *arg;
int *rets;
- int nb_rets;
int nb_jobs;
pthread_cond_t last_job_cond;
@@ -60,10 +59,11 @@ static void* attribute_align_arg worker(void *v)
int our_job = c->nb_jobs;
int nb_threads = c->nb_threads;
unsigned int last_execute = 0;
- int self_id;
+ int ret, self_id;
pthread_mutex_lock(&c->current_job_lock);
self_id = c->current_job++;
+
for (;;) {
while (our_job >= c->nb_jobs) {
if (c->current_job == nb_threads + c->nb_jobs)
@@ -81,7 +81,9 @@ static void* attribute_align_arg worker(void *v)
}
pthread_mutex_unlock(&c->current_job_lock);
- c->rets[our_job % c->nb_rets] = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
+ ret = c->func(c->ctx, c->arg, our_job, c->nb_jobs);
+ if (c->rets)
+ c->rets[our_job % c->nb_jobs] = ret;
pthread_mutex_lock(&c->current_job_lock);
our_job = c->current_job++;
@@ -117,7 +119,6 @@ static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
void *arg, int *ret, int nb_jobs)
{
ThreadContext *c = ctx->graph->internal->thread;
- int dummy_ret;
if (nb_jobs <= 0)
return 0;
@@ -129,13 +130,7 @@ static int thread_execute(AVFilterContext *ctx, avfilter_action_func *func,
c->ctx = ctx;
c->arg = arg;
c->func = func;
- if (ret) {
- c->rets = ret;
- c->nb_rets = nb_jobs;
- } else {
- c->rets = &dummy_ret;
- c->nb_rets = 1;
- }
+ c->rets = ret;
c->current_execute++;
pthread_cond_broadcast(&c->current_job_cond);
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