1515873 - Crash in mozilla::MediaManager::GetBackend

Status: RESOLVED FIXED

(Core :: WebRTC: Audio/Video, defect, P2)

Description

[[:philipp]]

This bug was filed from the Socorro interface and is
report bp-ba6fe475-33f6-4e21-bd89-880a80181221.
=============================================================

Top 10 frames of crashing thread:

0 xul.dll class mozilla::MediaEngine* mozilla::MediaManager::GetBackend dom/media/MediaManager.cpp:3516
1 xul.dll nsresult mozilla::media::LambdaTask<`lambda at z:/build/build/src/dom/media/MediaManager.cpp:3569:38'>::Run dom/media/systemservices/MediaTaskUtils.h:37
2 xul.dll bool MessageLoop::DeferOrRunPendingTask ipc/chromium/src/base/message_loop.cc:459
3 xul.dll MessageLoop::DoWork ipc/chromium/src/base/message_loop.cc:534
4 xul.dll mozilla::ipc::MessagePumpForNonMainUIThreads::DoRunLoop ipc/glue/MessagePump.cpp:403
5 xul.dll base::MessagePumpWin::Run ipc/chromium/src/base/message_pump_win.h:80
6 xul.dll MessageLoop::RunHandler ipc/chromium/src/base/message_loop.cc:318
7 xul.dll base::Thread::ThreadMain ipc/chromium/src/base/thread.cc:198
8 xul.dll static unsigned long `anonymous namespace'::ThreadFunc ipc/chromium/src/base/platform_thread_win.cc:30
9 kernel32.dll BaseThreadInitThunk 

=============================================================

crash reports during shutdown with this signature and MOZ_RELEASE_ASSERT(!sHasShutdown) are appearing cross-platform in desktop versions of firefox 64.

Comment 1

[Andreas Pehrson [:pehrsons]]

It seems to me like OnNavigation has started occurring *after* shutdown occasionally, sometime in 64.

We should detect this in OnNavigation and avoid trying to clean up more things after shutdown has occurred.

Comment 2

[Andreas Pehrson [:pehrsons]]

Attachment: Bug 1515873 - Avoid PostTask() after shutdown in MediaManager::OnNavigation. r?jib

Comment 3

[Andreas Pehrson [:pehrsons]]

Attachment: Bug 1515873 - Remove aWindowId arg from MediaManager::GetBackend. r?jib

It is unused.

Comment 4

[Andreas Pehrson [:pehrsons]]

Attachment: Bug 1515873 - Don't create a backend as part of cleanup. r?jib

There's no guarantee a backend exists when a MediaManager does, and
crash-stats shows that shutdown can occur between posting a task and running
it, making it illegal to create a backend anew.

We're safer off avoiding creating a new backend. The cleanup step we're trying
to do is only effective if a backend already exists anyway.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ef22d23a09a8
Remove aWindowId arg from MediaManager::GetBackend. r=jib
https://hg.mozilla.org/integration/autoland/rev/3de35d7cda2d
Don't create a backend as part of cleanup. r=jib

Comment 6

[Daniel Varga [:dvarga]]

https://hg.mozilla.org/mozilla-central/rev/ef22d23a09a8
https://hg.mozilla.org/mozilla-central/rev/3de35d7cda2d

Comment 7

[Andreas Pehrson [:pehrsons]]

Comment on attachment 9034095 [details]
Bug 1515873 - Don't create a backend as part of cleanup. r?jib

[Beta/Release Uplift Approval Request]

Feature/Bug causing the regression: unclear

User impact if declined: Potential shutdown crash

Is this code covered by automated tests?: No

Has the fix been verified in Nightly?: No

Needs manual test from QE?: No

If yes, steps to reproduce: 

List of other uplifts needed: None

Risk to taking this patch: Low

Why is the change risky/not risky? (and alternatives if risky): Trivial

String changes made/needed: None

Comment 8

[Ryan VanderMeulen [:RyanVM]]

Comment on attachment 9034095 [details]
Bug 1515873 - Don't create a backend as part of cleanup. r?jib

[Triage Comment]
Minor fix to avoid a shutdown crash introduced in Fx64. Approved for 65.0b9. Given the frequency, we may want to keep this on the radar for possible dot release inclusion also.

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/ab6723fb0cef
https://hg.mozilla.org/releases/mozilla-beta/rev/2641666a95ba