AudioSystem: fix cross deadlock
Do not hold gLockAPS when calling
AudioPolicyService::registerClient() in get_audio_policy_service().
registerClient() will need to acquire the AudioPolicyService mutex and
if at the same time a method called from AudioPolicyService
(with mutex held) calls back into AudioSystem and get_audio_policy_service()
a cross deadlock occurs.
Same preventive fix for get_audio_flinger().
Use a separate mutex for notification client list in AudioPolicyService.
This prevents deadlocking if registerClient() is called as a consequence of
AudioFlinger calling back into AudioPolicyManager while executing a method
with AudioPolicyService locked
Bug: 18403952.
Bug: 18450065.
Change-Id: Ia832e41aede8bc6c843fc615508fbdd74e0863b5
diff --git a/media/libmedia/AudioSystem.cpp b/media/libmedia/AudioSystem.cpp
index 0e608f8..1f8e9b6 100644
--- a/media/libmedia/AudioSystem.cpp
+++ b/media/libmedia/AudioSystem.cpp
@@ -51,33 +51,40 @@
sp<AudioSystem::AudioPortCallback> AudioSystem::gAudioPortCallback;
// establish binder interface to AudioFlinger service
-const sp<IAudioFlinger>& AudioSystem::get_audio_flinger()
+const sp<IAudioFlinger> AudioSystem::get_audio_flinger()
{
- Mutex::Autolock _l(gLock);
- if (gAudioFlinger == 0) {
- sp<IServiceManager> sm = defaultServiceManager();
- sp<IBinder> binder;
- do {
- binder = sm->getService(String16("media.audio_flinger"));
- if (binder != 0)
- break;
- ALOGW("AudioFlinger not published, waiting...");
- usleep(500000); // 0.5 s
- } while (true);
- if (gAudioFlingerClient == NULL) {
- gAudioFlingerClient = new AudioFlingerClient();
- } else {
- if (gAudioErrorCallback) {
- gAudioErrorCallback(NO_ERROR);
+ sp<IAudioFlinger> af;
+ sp<AudioFlingerClient> afc;
+ {
+ Mutex::Autolock _l(gLock);
+ if (gAudioFlinger == 0) {
+ sp<IServiceManager> sm = defaultServiceManager();
+ sp<IBinder> binder;
+ do {
+ binder = sm->getService(String16("media.audio_flinger"));
+ if (binder != 0)
+ break;
+ ALOGW("AudioFlinger not published, waiting...");
+ usleep(500000); // 0.5 s
+ } while (true);
+ if (gAudioFlingerClient == NULL) {
+ gAudioFlingerClient = new AudioFlingerClient();
+ } else {
+ if (gAudioErrorCallback) {
+ gAudioErrorCallback(NO_ERROR);
+ }
}
+ binder->linkToDeath(gAudioFlingerClient);
+ gAudioFlinger = interface_cast<IAudioFlinger>(binder);
+ LOG_ALWAYS_FATAL_IF(gAudioFlinger == 0);
+ afc = gAudioFlingerClient;
}
- binder->linkToDeath(gAudioFlingerClient);
- gAudioFlinger = interface_cast<IAudioFlinger>(binder);
- LOG_ALWAYS_FATAL_IF(gAudioFlinger == 0);
- gAudioFlinger->registerClient(gAudioFlingerClient);
+ af = gAudioFlinger;
}
-
- return gAudioFlinger;
+ if (afc != 0) {
+ af->registerClient(afc);
+ }
+ return af;
}
/* static */ status_t AudioSystem::checkAudioFlinger()
@@ -546,29 +553,37 @@
// establish binder interface to AudioPolicy service
-const sp<IAudioPolicyService>& AudioSystem::get_audio_policy_service()
+const sp<IAudioPolicyService> AudioSystem::get_audio_policy_service()
{
- Mutex::Autolock _l(gLockAPS);
- if (gAudioPolicyService == 0) {
- sp<IServiceManager> sm = defaultServiceManager();
- sp<IBinder> binder;
- do {
- binder = sm->getService(String16("media.audio_policy"));
- if (binder != 0)
- break;
- ALOGW("AudioPolicyService not published, waiting...");
- usleep(500000); // 0.5 s
- } while (true);
- if (gAudioPolicyServiceClient == NULL) {
- gAudioPolicyServiceClient = new AudioPolicyServiceClient();
+ sp<IAudioPolicyService> ap;
+ sp<AudioPolicyServiceClient> apc;
+ {
+ Mutex::Autolock _l(gLockAPS);
+ if (gAudioPolicyService == 0) {
+ sp<IServiceManager> sm = defaultServiceManager();
+ sp<IBinder> binder;
+ do {
+ binder = sm->getService(String16("media.audio_policy"));
+ if (binder != 0)
+ break;
+ ALOGW("AudioPolicyService not published, waiting...");
+ usleep(500000); // 0.5 s
+ } while (true);
+ if (gAudioPolicyServiceClient == NULL) {
+ gAudioPolicyServiceClient = new AudioPolicyServiceClient();
+ }
+ binder->linkToDeath(gAudioPolicyServiceClient);
+ gAudioPolicyService = interface_cast<IAudioPolicyService>(binder);
+ LOG_ALWAYS_FATAL_IF(gAudioPolicyService == 0);
+ apc = gAudioPolicyServiceClient;
}
- binder->linkToDeath(gAudioPolicyServiceClient);
- gAudioPolicyService = interface_cast<IAudioPolicyService>(binder);
- LOG_ALWAYS_FATAL_IF(gAudioPolicyService == 0);
- gAudioPolicyService->registerClient(gAudioPolicyServiceClient);
+ ap = gAudioPolicyService;
+ }
+ if (apc != 0) {
+ ap->registerClient(apc);
}
- return gAudioPolicyService;
+ return ap;
}
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