1885319 - Apply LLVM TSan fixes to both of our own clang and rust builds

Status: ASSIGNED

(Core :: Gecko Profiler, task, P3)

Description

[Nazım Can Altınova [:canova][:canaltinova on phabricator]]

Currently SIGPROF is an async signal on TSan codebase. TSan tries to delay the dispatch of async signals until it finds a blocking function call. It's very problematic for our case because some function calls are incorrectly marked as non-blocking: issue 1, issue 2.

Serge landed an LLVM patch to mark SIGPROF as sync function but I guess it'll take some time until it's released and we switch to it. And the same applies to Rust. We can patch our own clang and rust versions in the meantime.

Edit after updating the bug: The first patch I mentioned above is reverted by LLVM, so we need to fix it by applying https://github.com/llvm/llvm-project/pull/84162 and https://github.com/llvm/llvm-project/pull/86537 to both of our clang and rust builds.

Comment 1

[Nazım Can Altınova [:canova][:canaltinova on phabricator]]

Attachment: Bug 1885319 - Make SIGPROF a sync signal on TSan of our clang and rust builds r?sergesanspaille!,glandium!

Due to SIGPROF being async, it was hanging on some cases because some functions
were incorrectly marked non-blocking. This patch is merge to LLVM in:
https://github.com/llvm/llvm-project/pull/85188 But we want to patch our clang
here to start benefiting from that quickly.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d90b4451e543
Make SIGPROF a sync signal on TSan of our clang and rust builds r=sergesanspaille,glandium

Comment 3

[Iulian Moraru]

Backed out for causing multiple xpcshell failures.
This only happened on linux tsan.

• Push with failures

• Failure log example 1

• Failure log example 2

• Backout link

Comment 4

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

There is an r+ patch which didn't land and no activity in this bug for 2 weeks.
:canova, could you have a look please?
If you still have some work to do, you can add an action "Plan Changes" in Phabricator.
For more information, please visit BugBot documentation.

Comment 5

[Nazım Can Altınova [:canova][:canaltinova on phabricator]]

Abandoned the previous patch. That LLVM patch has been reverted so it means that we need to land the patches in https://github.com/llvm/llvm-project/pull/84162 and https://github.com/llvm/llvm-project/pull/86537 instead.

Comment 6

[Nazım Can Altınova [:canova][:canaltinova on phabricator]]

Converting this bug to apply the patches in https://github.com/llvm/llvm-project/pull/84162 and https://github.com/llvm/llvm-project/pull/86537 instead of applying the older reverted patch.