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author | Ian Lance Taylor <iant@golang.org> | 2021-07-28 21:09:31 -0700 |
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committer | Ian Lance Taylor <iant@golang.org> | 2021-07-29 15:30:38 +0000 |
commit | 70fd4e47d73b92fe90e44ac785e2f98f9df0ab67 (patch) | |
tree | b3e27a617fa1b6d191dac8a40c99142b96f1eb50 /src/runtime/crash_cgo_test.go | |
parent | 9eee0ed4391942c73157c868a9ddcfdef48982f9 (diff) | |
download | go-70fd4e47d73b92fe90e44ac785e2f98f9df0ab67.tar.gz go-70fd4e47d73b92fe90e44ac785e2f98f9df0ab67.zip |
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>
Diffstat (limited to 'src/runtime/crash_cgo_test.go')
-rw-r--r-- | src/runtime/crash_cgo_test.go | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go index 7d25c51aa2..5729942cee 100644 --- a/src/runtime/crash_cgo_test.go +++ b/src/runtime/crash_cgo_test.go @@ -282,6 +282,15 @@ func TestCgoTracebackContext(t *testing.T) { } } +func TestCgoTracebackContextPreemption(t *testing.T) { + t.Parallel() + got := runTestProg(t, "testprogcgo", "TracebackContextPreemption") + want := "OK\n" + if got != want { + t.Errorf("expected %q got %v", want, got) + } +} + func testCgoPprof(t *testing.T, buildArg, runArg, top, bottom string) { t.Parallel() if runtime.GOOS != "linux" || (runtime.GOARCH != "amd64" && runtime.GOARCH != "ppc64le") { |