commit 5d608082f60eaf3d8eaf81d9c711835cbe00dbb2
author Weiyin Jiang <wjiang@codeaurora.org> Thu Feb 01 17:24:33 2018 +0800
committer Gerrit - the friendly Code Review server <code-review@localhost> Wed May 09 01:01:59 2018 -0700
tree bed351fbdd77014a6a2b0f2df203e4a6339af181
parent addfa4a10052542091d2ccc8fea685cf0bada6f7

audio: move gef device change notification to the tail

It's thread unsafe to unlatch the device lock in the middle, active
usecase list may be accessed from other threads and results into race
condition.

Caching the stream information and notify device change at the tail of
select_devices(). In the wrost case, stale info gets notified which won't
harm.

Change-Id: I14f2473a304761d1b2d822135db4c70862c84415

hal/audio_hw.c

diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index fa83205..ef74440 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -2015,6 +2015,10 @@
     struct stream_out stream_out;
     audio_usecase_t hfp_ucid;
     int status = 0;
+    audio_devices_t audio_device;
+    audio_channel_mask_t channel_mask;
+    int sample_rate;
+    int acdb_id;
 
     ALOGD("%s for use case (%s)", __func__, use_case_table[uc_id]);
 
@@ -2255,14 +2259,11 @@
             usecase->stream.out->app_type_cfg.sample_rate = DEFAULT_OUTPUT_SAMPLING_RATE;
         }
 
-        /* Notify device change info to effect clients registered */
-        pthread_mutex_unlock(&adev->lock);
-        audio_extn_gef_notify_device_config(
-                usecase->stream.out->devices,
-                usecase->stream.out->channel_mask,
-                usecase->stream.out->app_type_cfg.sample_rate,
-                platform_get_snd_device_acdb_id(usecase->out_snd_device));
-        pthread_mutex_lock(&adev->lock);
+        /* Cache stream information to be notified to gef clients */
+        audio_device = usecase->stream.out->devices;
+        channel_mask = usecase->stream.out->channel_mask;
+        sample_rate = usecase->stream.out->app_type_cfg.sample_rate;
+        acdb_id = platform_get_snd_device_acdb_id(usecase->out_snd_device);
     }
     enable_audio_route(adev, usecase);
 
@@ -2319,6 +2320,16 @@
          }
     }
 
+    /* Notify device change info to effect clients registered
+     * NOTE: device lock has to be unlock temporarily here.
+     * To the worst case, we notify stale info to clients.
+     */
+    if (usecase->type == PCM_PLAYBACK) {
+        pthread_mutex_unlock(&adev->lock);
+        audio_extn_gef_notify_device_config(audio_device, channel_mask, sample_rate, acdb_id);
+        pthread_mutex_lock(&adev->lock);
+    }
+
     ALOGD("%s: done",__func__);
 
     return status;