Simplify the loopfilter synchronization logic in VP8 encoder

This patch was to fix a reported Hangouts deadlock/freezing issue
in VP8 encoder(issue 27232610). The original encoder loopfilter
synchronization happened in the following frame, which was prone
to causing problems in some complex use cases. This patch simplified
the synchronization logic.

More testing needs to be done.

Change-Id: I38fd3f35d11f98fae1e44546aa5e4c6d6e19c4be

3 files changed, 2 insertions, 34 deletions

diff --git a/vp8/encoder/ethreading.c b/vp8/encoder/ethreading.c
index 4f689c4bc..2a0c2987b 100644
--- a/vp8/encoder/ethreading.c
+++ b/vp8/encoder/ethreading.c
@@ -518,7 +518,6 @@ int vp8cx_create_encoder_threads(VP8_COMP *cpi)
 
     cpi->b_multi_threaded = 0;
     cpi->encoding_thread_count = 0;
-    cpi->b_lpf_running = 0;
 
     pthread_mutex_init(&cpi->mt_mutex, NULL);
 
diff --git a/vp8/encoder/onyx_if.c b/vp8/encoder/onyx_if.c
index 93c457008..88c191e94 100644
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -1531,15 +1531,6 @@ void vp8_change_config(VP8_COMP *cpi, VP8_CONFIG *oxcf)
     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;
@@ -3638,15 +3629,6 @@ static void encode_frame_to_data_rate
     /* 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
-
     if(cpi->force_next_frame_intra)
     {
         cm->frame_type = KEY_FRAME;  /* delayed intra frame */
@@ -4375,8 +4357,6 @@ static void encode_frame_to_data_rate
             vp8_setup_key_frame(cpi);
         }
 
-
-
 #if CONFIG_REALTIME_ONLY & CONFIG_ONTHEFLY_BITPACKING
         {
             if(cpi->oxcf.error_resilient_mode)
@@ -4842,7 +4822,6 @@ static void encode_frame_to_data_rate
     {
         /* start loopfilter in separate thread */
         sem_post(&cpi->h_event_start_lpf);
-        cpi->b_lpf_running = 1;
     }
     else
 #endif
@@ -4874,11 +4853,10 @@ static void encode_frame_to_data_rate
     vp8_pack_bitstream(cpi, dest, dest_end, size);
 
 #if CONFIG_MULTITHREAD
-    /* if PSNR packets are generated we have to wait for the lpf */
-    if (cpi->b_lpf_running && cpi->b_calculate_psnr)
+    /* wait for the lpf thread done */
+    if (cpi->b_multi_threaded)
     {
         sem_wait(&cpi->h_event_end_lpf);
-        cpi->b_lpf_running = 0;
     }
 #endif
 
@@ -5838,14 +5816,6 @@ int vp8_get_preview_raw_frame(VP8_COMP *cpi, YV12_BUFFER_CONFIG *dest, vp8_ppfla
     {
         int ret;
 
-#if CONFIG_MULTITHREAD
-        if(cpi->b_lpf_running)
-        {
-            sem_wait(&cpi->h_event_end_lpf);
-            cpi->b_lpf_running = 0;
-        }
-#endif
-
 #if CONFIG_POSTPROC
         cpi->common.show_frame_mi = cpi->common.mi;
         ret = vp8_post_proc_frame(&cpi->common, dest, flags);
diff --git a/vp8/encoder/onyx_int.h b/vp8/encoder/onyx_int.h
index 2b2f7a0a9..6ede9b95a 100644
--- a/vp8/encoder/onyx_int.h
+++ b/vp8/encoder/onyx_int.h
@@ -536,7 +536,6 @@ typedef struct VP8_COMP
     int mt_sync_range;
     int b_multi_threaded;
     int encoding_thread_count;
-    int b_lpf_running;
 
     pthread_t *h_encoding_thread;
     pthread_t h_filter_thread;