Bug 221027

Summary: REGRESSION(r271929): MobileSafari hangs upon launch due to a trivial deadlock in IOSurfacePool::setPoolSize
Product: WebKit Reporter: Ryosuke Niwa <rniwa>
Component: WebCore Misc.Assignee: Ryosuke Niwa <rniwa>
Status: RESOLVED FIXED    
Severity: Normal CC: cdumez, saam, simon.fraser, thorton, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 221010    
Attachments:
Description Flags
Patch none

Description Ryosuke Niwa 2021-01-27 00:48:30 PST 
We hang inside IOSurfacePool::setPoolSize(unsigned long) via IOSurfacePool::discardAllSurfacesInternal()
as the latter tries to grab the lock while setPoolSize holds a locker.
Comment 1 Ryosuke Niwa 2021-01-27 00:53:27 PST 
Created attachment 418511 [details]
Patch
Comment 2 Ryosuke Niwa 2021-01-27 03:06:22 PST 
Comment on attachment 418511 [details]
Patch

Clearing flags on attachment: 418511

Committed r271943: <https://trac.webkit.org/changeset/271943>
Comment 3 Ryosuke Niwa 2021-01-27 03:06:25 PST 
All reviewed patches have been landed.  Closing bug.
Comment 4 Radar WebKit Bug Importer 2021-01-27 03:07:14 PST 
<rdar://problem/73656115>
Comment 5 Chris Dumez 2021-01-27 07:38:12 PST 
Comment on attachment 418511 [details]
Patch

Thanks for fixing.
Comment 6 Saam Barati 2021-01-27 13:17:02 PST 
Comment on attachment 418511 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=418511&action=review

> Source/WebCore/platform/graphics/cg/IOSurfacePool.cpp:332
> +void IOSurfacePool::discardAllSurfacesInternal()

nit: A style I like in JSC is we do this by keeping the same function name, and requiring a locker to be passed in.

So, we'd have:

void discardAllSurfaces()
and
void discardAllSurfaces(const LockHolder&)

and the former would call the latter with the locker as an argument. Same with `evict`