commit 7dbf7ee1ad7782e42fdacd8b4a2d88866863401b
author Song Zhao <song.zhao@amlogic.com> Thu Sep 01 14:50:02 2022 -0700
committer Song Zhao <song.zhao@amlogic.com> Thu Sep 01 14:54:06 2022 -0700
tree d4b18466bb6c54ebef583bd6006fc7d5cd533a74
parent 47961d76b7fcb8f49dd282aa1fffcf6dbc6ca24c

avsync-lib: CB0 fix a busy loop inside avs_poll [1/1]

PD#TV-62888

Problem:
avs_poll thread take 100% CPU because poll returns with unexpected
revent.

Solution:
Detect unexpected revent and sleep before retry

Verify:
T5D + Roxton

Change-Id: I5eec51e48dbd3c377e901bc3c3d309e23f15041a
Signed-off-by: Song Zhao <song.zhao@amlogic.com>

src/avsync.c

diff --git a/src/avsync.c b/src/avsync.c
index 5f210a0..4009db2 100644
--- a/src/avsync.c
+++ b/src/avsync.c
@@ -1531,6 +1531,7 @@
     int ret = 0;
     struct av_sync_session *avsync = (struct av_sync_session *)arg;
     const int fd = avsync->fd;
+    int poll_timeout = 10;
     struct pollfd pfd = {
       /* default blocking capture */
       .events =  POLLIN | POLLRDNORM | POLLPRI | POLLOUT | POLLWRNORM,
@@ -1541,25 +1542,31 @@
     prctl (PR_SET_NAME, "avs_poll");
     log_info("[%d]enter", avsync->session_id);
 
-    if (avsync->type == AV_SYNC_TYPE_AUDIO)
+    if (avsync->type == AV_SYNC_TYPE_AUDIO) {
         sflag = SRC_A;
-    else if (avsync->type == AV_SYNC_TYPE_VIDEO)
+    } else if (avsync->type == AV_SYNC_TYPE_VIDEO) {
         sflag = SRC_V;
+        poll_timeout = 100;
+    }
 
     while (!avsync->quit_poll) {
         for (;;) {
-          ret = poll(&pfd, 1, 10);
+          ret = poll(&pfd, 1, poll_timeout);
           if (ret > 0)
               break;
           if (avsync->quit_poll)
               goto exit;
-          if (errno == EINTR)
+          if (errno == EINTR) {
+              log_debug("[%d] poll interrupted", avsync->session_id);
               continue;
+          }
         }
 
         /* error handling */
-        if (pfd.revents & POLLERR)
-            log_error("[%d]POLLERR received", avsync->session_id);
+        if (pfd.revents & POLLERR) {
+            usleep(poll_timeout * 1000);
+            continue;
+        }
 
         /* mode change. Non-exclusive wait so all the processes
          * shall be woken up
@@ -1576,6 +1583,9 @@
             else if (avsync->type == AV_SYNC_TYPE_VIDEO)
                 handle_mode_change_v(avsync, stat, v_active, a_active, v_timeout);
             usleep(10000);
+        } else {
+            log_debug("[%d] unexpected revents %x", avsync->session_id, pfd.revents);
+            usleep(poll_timeout * 1000);
         }
     }
 exit: