commit feeb11639df4160701777a5abc05be345e74d1eb
author Gautam Manam <gmanam@codeaurora.org> Thu Dec 24 14:08:04 2020 +0530
committer Gerrit - the friendly Code Review server <code-review@localhost> Tue Dec 29 22:01:37 2020 -0800
tree 16407da7d08a7cb0db3b91847da1a164766ba9f6
parent d4e8ced33fbadf778459b4eb36d31343f3068a2f

hal: deadlock with pause and SSR for compressed offload

For compress offload playback, during SSR offline
callback will hold out and latch lock and set
offload state to idle and wait on compress
offload thread state to be marked as unblocked.

In the mean time pause is triggered and it acquires
out lock and waits for out_latch lock.

And in another thread compress_wait completes and
wait for out lock causing dead lock.

Fix this by moving latch lock to protect only
offload_state, so that latch lock can be released.

Change-Id: Iec42eaf6c18477b4f87bb5bafe54fb346c7af73b

hal/audio_hw.c

diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 3d98f06..78f1182 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -3347,10 +3347,12 @@
     return 0;
 }
 
-/* must be called with out->lock and latch lock */
+/* must be called with out->lock */
 static void stop_compressed_output_l(struct stream_out *out)
 {
+    pthread_mutex_lock(&out->latch_lock);
     out->offload_state = OFFLOAD_STATE_IDLE;
+    pthread_mutex_unlock(&out->latch_lock);
     out->playback_started = 0;
     out->send_new_metadata = 1;
     if (out->compr != NULL) {
@@ -3608,11 +3610,9 @@
 static int destroy_offload_callback_thread(struct stream_out *out)
 {
     lock_output_stream(out);
-    pthread_mutex_lock(&out->latch_lock);
     stop_compressed_output_l(out);
     send_offload_cmd_l(out, OFFLOAD_CMD_EXIT);
 
-    pthread_mutex_unlock(&out->latch_lock);
     pthread_mutex_unlock(&out->lock);
     pthread_join(out->offload_thread, (void **) NULL);
     pthread_cond_destroy(&out->offload_cond);
@@ -4507,9 +4507,7 @@
             adev->adm_deregister_stream(adev->adm_data, out->handle);
 
         if (is_offload_usecase(out->usecase)) {
-            pthread_mutex_lock(&out->latch_lock);
             stop_compressed_output_l(out);
-            pthread_mutex_unlock(&out->latch_lock);
         }
 
         pthread_mutex_lock(&adev->lock);
@@ -4584,9 +4582,7 @@
     // is needed e.g. when SSR happens within compress_open
     // since the stream is active, offload_callback_thread is also active.
     if (out->flags & AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD) {
-        pthread_mutex_lock(&out->latch_lock);
         stop_compressed_output_l(out);
-        pthread_mutex_unlock(&out->latch_lock);
     }
     pthread_mutex_unlock(&out->lock);
 
@@ -4625,9 +4621,7 @@
             adev->adm_deregister_stream(adev->adm_data, out->handle);
 
         if (is_offload_usecase(out->usecase)) {
-            pthread_mutex_lock(&out->latch_lock);
             stop_compressed_output_l(out);
-            pthread_mutex_unlock(&out->latch_lock);
         }
 
         out->standby = true;
@@ -6470,12 +6464,13 @@
         lock_output_stream(out);
         pthread_mutex_lock(&out->latch_lock);
         if (out->offload_state == OFFLOAD_STATE_PAUSED) {
+            pthread_mutex_unlock(&out->latch_lock);
             stop_compressed_output_l(out);
         } else {
             ALOGW("%s called in invalid state %d", __func__, out->offload_state);
+            pthread_mutex_unlock(&out->latch_lock);
         }
         out->written = 0;
-        pthread_mutex_unlock(&out->latch_lock);
         pthread_mutex_unlock(&out->lock);
         ALOGD("copl(%p):out of compress flush", out);
         return 0;