tree b8e6d259e7ec8fbccc9020cdfd19166866d3a5f0
parent 57864d6c8601cf31b1c1e8b88dbcaa34aa833981
author Kostya Kortchinsky <kostyak@google.com> 1578598996 -0800
committer Copybara-Service <copybara-worker@google.com> 1598597793 -0700

[scudo][standalone] Fork support

Summary:
fork() wasn't well (or at all) supported in Scudo. This materialized
in deadlocks in children.

In order to properly support fork, we will lock the allocator pre-fork
and unlock it post-fork in parent and child. This is done via a
`pthread_atfork` call installing the necessary handlers.

A couple of things suck here: this function allocates - so this has to
be done post initialization as our init path is not reentrance, and it
doesn't allow for an extra pointer - so we can't pass the allocator we
are currently working with.

In order to work around this, I added a post-init template parameter
that gets executed once the allocator is initialized for the current
thread. Its job for the C wrappers is to install the atfork handlers.

I reorganized a bit the impacted area and added some tests, courtesy
of cferris@ that were deadlocking prior to this fix.

Subscribers: jfb, #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D72470

GitOrigin-RevId: 9ef6faf49670e18eb1ba04105a7c70b450cdaa71