shithub: libvpx

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Fix loopfilter race condition in multithreaded encoder

Race was introduced by https://gerrit.chromium.org/gerrit/15563.

If loopfilter related config params were changed between frames, or
after a KEY frame, there could be a mismatch between encoder's and
decoder's recontructed image. In worst case, when frame buffers are
reallocated because of a size change, the loopfilter could
do an invalid data access (segmentation fault).

Fixes:
Sync with the loopfilter before applying any encoder changes in
vp8_change_config().
Moved the loopfilter synching to the top of
encode_frame_to_data_rate() so that it's done before any alteration of
the encoder.

Change-Id: Ide5245d2a2aeed78752de750c0110bc4b46f5b7b

--- a/vp8/encoder/onyx_if.c

+++ b/vp8/encoder/onyx_if.c

@@ -1412,6 +1412,15 @@

     if (!oxcf)

         return;

+#if CONFIG_MULTITHREAD

+    /*  wait for the last picture loopfilter thread done */

+    if (cpi->b_lpf_running)

+    {

+        sem_wait(&cpi->h_event_end_lpf);

+        cpi->b_lpf_running = 0;

+    }

+#endif

+

     if (cm->version != oxcf->Version)

     {

         cm->version = oxcf->Version;

@@ -3194,6 +3203,15 @@

     // Clear down mmx registers to allow floating point in what follows

     vp8_clear_system_state();

+#if CONFIG_MULTITHREAD

+    /*  wait for the last picture loopfilter thread done */

+    if (cpi->b_lpf_running)

+    {

+        sem_wait(&cpi->h_event_end_lpf);

+        cpi->b_lpf_running = 0;

+    }

+#endif

+

     // Test code for segmentation of gf/arf (0,0)

     //segmentation_test_function( cpi);

@@ -3748,14 +3766,7 @@

             vp8_setup_key_frame(cpi);

         }

-#if CONFIG_MULTITHREAD

-        /*  wait for the last picture loopfilter thread done */

-        if (cpi->b_lpf_running)

-        {

-            sem_wait(&cpi->h_event_end_lpf);

-            cpi->b_lpf_running = 0;

-        }

-#endif

+

 #if CONFIG_REALTIME_ONLY & CONFIG_ONTHEFLY_BITPACKING

         {

-- 

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