1475270 - Avoid deadlock when pausing the compositor while gfxVRExternal is waiting for a SubmitFrame result

Status: RESOLVED FIXED

(Core :: WebVR, enhancement)

Description

[Imanol Fernandez]

Firefox Reality pauses the compositor when gfxVRExternal presentation begins.

There is a race condition which causes a deadlock. It happens when pausing the compositor while gfxVRExternal is waiting for a SubmitFrame result.

Comment 1

[Imanol Fernandez]

Attachment: Fixes the deadlock race condition

Submited patch that fixes the deadlock race condition

Comment 2

[:kip (Kearwood Gilbert)]

Comment on attachment 8991651 [details] [diff] [review]
Fixes the deadlock race condition

Review of attachment 8991651 [details] [diff] [review]:
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Thanks for tracking this down!  We need just a couple small modifications to land this:

Adding this flag is a good idea; however, it would be best to minimize the amount of platform specific members and code.  WE could rename to something describing its effect, in a way useful for all platforms.
I would suggest renaming to "mSuppressFrames" and removing the #ifdef around the early exit added to gfxVRExternal.cpp.
Also, any new members added to VRDisplayState need to be included in the IPC serialization code in VRMessageUtils.h.

Comment 3

[Imanol Fernandez]

Attachment: supress_frames_api.diff

Latest patch with the modifications that Kip recommended

Comment 4

[:kip (Kearwood Gilbert)]

Comment on attachment 8991725 [details] [diff] [review]
supress_frames_api.diff

Looks good thanks!

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/452da58e5a47
Avoid deadlock when pausing the compositor while gfxVRExternal is waiting for a SubmitFrame result; r=kip

Comment 6

[Eliza Balazs [:ebalazs_]]

https://hg.mozilla.org/mozilla-central/rev/452da58e5a47