[FFmpeg-devel] [PATCH 3/6] pthread_frame: call update_context_from_user() after acquiring lock.

[Ronald S. Bultje]

Otherwise the thread may still be in the middle of decoding a previous
frame, which would effectively trigger a race condition on any field
concurrently read and written.
---
 libavcodec/pthread_frame.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/libavcodec/pthread_frame.c b/libavcodec/pthread_frame.c
index 34c36d8..6cc43f6 100644
--- a/libavcodec/pthread_frame.c
+++ b/libavcodec/pthread_frame.c
@@ -379,7 +379,8 @@ static void release_delayed_buffers(PerThreadContext *p)
     }
 }
 
-static int submit_packet(PerThreadContext *p, AVPacket *avpkt)
+static int submit_packet(PerThreadContext *p, AVCodecContext *user_avctx,
+                         AVPacket *avpkt)
 {
     FrameThreadContext *fctx = p->parent;
     PerThreadContext *prev_thread = fctx->prev_thread;
@@ -391,6 +392,12 @@ static int submit_packet(PerThreadContext *p, AVPacket *avpkt)
 
     pthread_mutex_lock(&p->mutex);
 
+    ret = update_context_from_user(p->avctx, user_avctx);
+    if (ret) {
+        pthread_mutex_unlock(&p->mutex);
+        return ret;
+    }
+
     release_delayed_buffers(p);
 
     if (prev_thread) {
@@ -479,10 +486,7 @@ int ff_thread_decode_frame(AVCodecContext *avctx,
      */
 
     p = &fctx->threads[fctx->next_decoding];
-    err = update_context_from_user(p->avctx, avctx);
-    if (err)
-        goto finish;
-    err = submit_packet(p, avpkt);
+    err = submit_packet(p, avctx, avpkt);
     if (err)
         goto finish;
 
-- 
2.8.1