tree d2c8dfa28092ff8c715c817a9e9574e076906669
parent 623d653db7cd2287305347196f7f4742b6b1fb38
author Ian Lance Taylor <iant@golang.org> 1561746015 -0700
committer Ian Lance Taylor <iant@golang.org> 1561873711 +0000

runtime: use a pipe to wake up signal_recv on Darwin

The implementation of semaphores, and therefore notes, used on Darwin
is not async-signal-safe. The runtime has one case where a note needs
to be woken up from a signal handler: the call to notewakeup in sigsend.
That notewakeup call is only called on a single note, and it doesn't
need the full functionality of notes: nothing ever does a timed wait on it.
So change that one note to use a different implementation on Darwin,
based on a pipe. This lets the wakeup code use the write call, which is
async-signal-safe.

Fixes #31264

Change-Id: If705072d7a961dd908ea9d639c8d12b222c64806
Reviewed-on: https://go-review.googlesource.com/c/go/+/184169
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>