[PATCH] D33325: [sanitizer] Avoid possible deadlock in child process after fork

[Evgenii Stepanov via Phabricator via llvm-commits]

eugenis added a comment.

This change is causing problems on Linux. The immediate issue is Tcl, which creates new threads from a pthread_atfork() child handler. The handler is called from libc's fork(), and pthread_create tries to acquire the StackDepot lock before it is released in the fork interceptor.

Tcl is broken, of course:

  If a fork() call in a multi-threaded process leads to a child fork handler calling any function that is not async-signal-safe, the behavior is undefined.

But in general, even malloc() called from pthread_atfork() will deadlock with this change.
It looks like the right way to do this is call pthread_atfork() as early as possible to setup lock/unlock handlers for the allocator and the stack depot.

I'll revert this change in the meantime.


Repository:
  rL LLVM

https://reviews.llvm.org/D33325