pthread : Remove lock/unlock pairs in worker loop to avoid unexpected state changes.

Reviewed-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/pthread.c

@@ -365,21 +365,17 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
     AVCodecContext *avctx = p->avctx;
     AVCodec *codec = avctx->codec;
 
+    pthread_mutex_lock(&p->mutex);
     while (1) {
         int i;
-        if (p->state == STATE_INPUT_READY && !fctx->die) {
-            pthread_mutex_lock(&p->mutex);
             while (p->state == STATE_INPUT_READY && !fctx->die)
                 pthread_cond_wait(&p->input_cond, &p->mutex);
-            pthread_mutex_unlock(&p->mutex);
-        }
 
         if (fctx->die) break;
 
         if (!codec->update_thread_context && (avctx->thread_safe_callbacks || avctx->get_buffer == avcodec_default_get_buffer))
             ff_thread_finish_setup(avctx);
 
-        pthread_mutex_lock(&p->mutex);
         avcodec_get_frame_defaults(&p->frame);
         p->got_frame = 0;
         p->result = codec->decode(avctx, &p->frame, &p->got_frame, &p->avpkt);
@@ -397,9 +393,8 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
         pthread_cond_broadcast(&p->progress_cond);
         pthread_cond_signal(&p->output_cond);
         pthread_mutex_unlock(&p->progress_mutex);
-
-        pthread_mutex_unlock(&p->mutex);
     }
+    pthread_mutex_unlock(&p->mutex);
 
     return NULL;
 }