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runtime: don't test sig.inuse in sigsend

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Signals can be delivered on a different thread. There is no necessary
happens-before relationship between setting sig.inuse in signal_enable
and checking it in sigsend. It is theoretically possible, if unlikely,
that sig.inuse is set by thread 1, thread 2 receives a signal, does not
see that sig.inuse is set, and discards the signal. This could happen
if the signal is received immediately after the first call to signal_enable.

For #33174

Change-Id: Idb0f1c77847b7d4d418bd139e801c0c4460531d2
Reviewed-on: https://go-review.googlesource.com/c/go/+/312131
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
This commit is contained in:
Ian Lance Taylor 2021-04-20 17:02:37 -07:00
parent 190cb937f7
commit c33ced6d8a
1 changed files with 1 additions and 1 deletions
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2
src/runtime/sigqueue.go
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@ -72,7 +72,7 @@ const (
// It runs from the signal handler, so it's limited in what it can do. // It runs from the signal handler, so it's limited in what it can do.
func sigsend(s uint32) bool { func sigsend(s uint32) bool {
bit := uint32(1) << uint(s&31) bit := uint32(1) << uint(s&31)
if !sig.inuse || s >= uint32(32*len(sig.wanted)) { if s >= uint32(32*len(sig.wanted)) {
return false return false
} }