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Ian Lance Taylor 70fd4e47d7 runtime: avoid possible preemption when returning from Go to C
When returning from Go to C, it was possible for the goroutine to be
preempted after calling unlockOSThread. This could happen when there
a context function installed by SetCgoTraceback set a non-zero context,
leading to a defer call in cgocallbackg1. The defer function wrapper,
introduced in 1.17 as part of the regabi support, was not nosplit,
and hence was a potential preemption point. If it did get preempted,
the G would move to a new M. It would then attempt to return to C
code on a different stack, typically leading to a SIGSEGV.

Fix this in a simple way by postponing the unlockOSThread until after
the other defer. Also check for the failure condition and fail early,
rather than waiting for a SIGSEGV.

Without the fix to cgocall.go, the test case fails about 50% of the
time on my laptop.

Fixes #47441

Change-Id: Ib8ca13215bd36cddc2a49e86698824a29c6a68ba
Reviewed-on: https://go-review.googlesource.com/c/go/+/338197
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
2021-07-29 15:30:38 +00:00
.github
api reflect: add Value.CanConvert 2021-07-21 19:25:48 +00:00
doc doc: clarify non-nil zero length slice to array pointer conversion 2021-07-26 17:47:47 +00:00
lib/time lib/time, time/tzdata: update tzdata to 2021a 2021-01-25 16:08:46 +00:00
misc misc/cgo: generate Windows import libraries for clang 2021-06-13 23:53:43 +00:00
src runtime: avoid possible preemption when returning from Go to C 2021-07-29 15:30:38 +00:00
test cmd/compile: do not change field offset in ABI analysis 2021-07-22 20:47:59 +00:00
.gitattributes
.gitignore internal/buildcfg: move build configuration out of cmd/internal/objabi 2021-04-16 19:20:53 +00:00
AUTHORS A+C: update name 2021-06-01 17:08:12 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00
CONTRIBUTING.md
CONTRIBUTORS A+C: update name 2021-06-01 17:08:12 +00:00
LICENSE
PATENTS
README.md README: pull gopher image from website 2021-02-16 18:25:10 +00:00
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