1835110 - Warnings of potential deadlock in Android font backend

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, defect)

Description

[Jonathan Kew [:jfkthame]]

As noted in bug 1827756 comment 1, we see a number of warnings of a potential deadlock issue in the Android font code:

04-12 21:59:49.331 11661 11676 I Gecko   : [Child 11661, Main Thread] WARNING: Potential deadlock detected:
04-12 21:59:49.331 11661 11676 I Gecko   : Cyclical dependency starts at
04-12 21:59:49.331 11661 11676 I Gecko   : Mutex : gfxFontEntry lock
04-12 21:59:49.331 11661 11676 I Gecko   : Next dependency:
04-12 21:59:49.331 11661 11676 I Gecko   : Mutex : SharedFTFace::mLock (currently acquired)
04-12 21:59:49.331 11661 11676 I Gecko   : Cycle completed at
04-12 21:59:49.331 11661 11676 I Gecko   : Mutex : gfxFontEntry lock
04-12 21:59:49.331 11661 11676 I Gecko   : Deadlock may happen for some other execution

I don't believe our tests are in fact deadlocking there at present -- the timeouts in bug 1827756 must have some other cause -- but the warning is indicating a potential issue that we should fix anyway.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1835110 - Avoid potential deadlock in FT2FontEntry::HasFontTable. r=#gfx-reviewers

Checking logcat from test runs at
https://treeherder.mozilla.org/jobs?repo=try&revision=fc75475d3cd5dcacbbc74b0c9a58a89ae6c97119
we can see that the "potential deadlock" warning no longer appears.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1763414

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/34e423bf5086
Avoid potential deadlock in FT2FontEntry::HasFontTable. r=gfx-reviewers,bradwerth

Comment 4

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/34e423bf5086

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:jfkthame, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox114 to wontfix.

For more information, please visit BugBot documentation.

Comment 6

[Jonathan Kew [:jfkthame]]

I don't think this needs uplift -- afaict, we were not in fact encountering a deadlock, as noted in comment 0, just logging a warning.