[FFmpeg-devel] [PATCH] lavd/alsa: fixes ALSA resource leak on closing the PCM handle

[Takayuki 'January June' Suwa]

By avoiding thread race condition (CAS-ing with null handle)

---
 libavdevice/alsa.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/libavdevice/alsa.c b/libavdevice/alsa.c
index 1bbff30..81187ab 100644
--- a/libavdevice/alsa.c
+++ b/libavdevice/alsa.c
@@ -30,6 +30,7 @@
 
 #include <alsa/asoundlib.h>
 #include "avdevice.h"
+#include "libavutil/atomic.h"
 #include "libavutil/avassert.h"
 #include "libavutil/channel_layout.h"
 
@@ -299,13 +300,14 @@ av_cold int ff_alsa_open(AVFormatContext *ctx, snd_pcm_stream_t mode,
 av_cold int ff_alsa_close(AVFormatContext *s1)
 {
     AlsaData *s = s1->priv_data;
+    snd_pcm_t *h = avpriv_atomic_ptr_cas((void* volatile *)&s->h, s->h, 0);
 
-    snd_pcm_nonblock(s->h, 0);
-    snd_pcm_drain(s->h);
+    snd_pcm_nonblock(h, 0);
+    snd_pcm_drain(h);
     av_freep(&s->reorder_buf);
     if (CONFIG_ALSA_INDEV)
         ff_timefilter_destroy(s->timefilter);
-    snd_pcm_close(s->h);
+    snd_pcm_close(h);
     return 0;
 }