evr/sample: Avoid a race condition when releasing a tracked sample.

Same as b1807751. Signed-off-by: Nikolay Sivov <nsivov@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

evr/sample: Avoid a race condition when releasing a tracked sample.
ce71f5a0 · Nikolay Sivov · Alexandre Julliard · 1d7d3f58 · ce71f5a0
Commit ce71f5a0 authored May 10, 2022 by Nikolay Sivov Committed by Alexandre Julliard May 11, 2022
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Showing with 7 additions and 5 deletions

sample.c dlls/evr/sample.c +7 -5

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--- a/dlls/evr/sample.c
+++ b/dlls/evr/sample.c
@@ -920,19 +920,21 @@ static ULONG WINAPI video_sample_AddRef(IMFSample *iface)
 static ULONG WINAPI video_sample_Release(IMFSample *iface)
 {
    struct video_sample *sample = impl_from_IMFSample(iface);
-    ULONG refcount;
+    ULONG refcount = InterlockedDecrement(&sample->refcount);
+    IMFAsyncResult *tracked_result = NULL;

    IMFSample_LockStore(sample->sample);
-    if (sample->tracked_result && sample->tracked_refcount == (sample->refcount - 1))
+    if (sample->tracked_result && sample->tracked_refcount == refcount)
    {
-        video_sample_tracking_thread_invoke(sample->tracked_result);
-        IMFAsyncResult_Release(sample->tracked_result);
+        tracked_result = sample->tracked_result;
+        video_sample_tracking_thread_invoke(tracked_result);
        sample->tracked_result = NULL;
        sample->tracked_refcount = 0;
    }
    IMFSample_UnlockStore(sample->sample);

-    refcount = InterlockedDecrement(&sample->refcount);
+    if (tracked_result)
+        IMFAsyncResult_Release(tracked_result);

    TRACE("%p, refcount %lu.\n", iface, refcount);