1277943 - Debug Thread of nsSocketTransportService::DebugMutexAutoLock not threadsafe

Status: RESOLVED FIXED

Description

[Patrick McManus [:mcmanus]]

over in 1152048 we were looking for cases where the socketthread lock was obtained re-entrantly by adding a DIAGNOSTIC_ASSERT.. and we found and fixed one in the ~42 era.

Unfortunately there are a few crashes from that DIAGNOSTIC_ASSERT (which only happens on nighty/aurora) still hanging around in current builds that don't seem related to recursive locking.

This one is from 48 https://crash-stats.mozilla.com/report/index/270eb52d-4d51-40ac-8cfd-d4bb42160526#allthreads

everything in that stack trace looks fine to me.

however, the debug thread member variable is defined as relaxed - which provides no memory ordering guarnatees.
    static Atomic<PRThread *, Relaxed> sDebugOwningThread;

based on the fact that I don't see crashes of the flavor we are looking for, and this is a red herring I am posting a patch that removes the AutoLock wrapper and just returns it to a straight autolock.

Comment 1

[Patrick McManus [:mcmanus]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=4d5dfc9a6e76

Comment 2

[Patrick McManus [:mcmanus]]

Created attachment 8759817 [details] [diff] [review]
atomic fix to sockettransport::debugautomutex

Comment 3

[Patrick McManus [:mcmanus]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/f457175b1c4fe381a05c1fbde3776199b37b0250
Bug 1277943 - atomic fix to sockettransport::debugautomutex r=hurley

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/f457175b1c4f