runtime: convert pendingPreemptSignals to atomic type

For #53821.

Change-Id: I106adbcb00b7b887d54001c2d7d97345a13cc662
Reviewed-on: https://go-review.googlesource.com/c/go/+/419436
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 32782b3c65..cea7f37d13 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -1547,7 +1547,7 @@ found:
 		// Make sure pendingPreemptSignals is correct when an M exits.
 		// For #41702.
 		if atomic.Load(&mp.signalPending) != 0 {
-			atomic.Xadd(&pendingPreemptSignals, -1)
+			pendingPreemptSignals.Add(-1)
 		}
 	}
 
@@ -4036,7 +4036,7 @@ func syscall_runtime_AfterForkInChild() {
 // pendingPreemptSignals is the number of preemption signals
 // that have been sent but not received. This is only used on Darwin.
 // For #41702.
-var pendingPreemptSignals uint32
+var pendingPreemptSignals atomic.Int32
 
 // Called from syscall package before Exec.
 //
@@ -4048,7 +4048,7 @@ func syscall_runtime_BeforeExec() {
 	// On Darwin, wait for all pending preemption signals to
 	// be received. See issue #41702.
 	if GOOS == "darwin" || GOOS == "ios" {
-		for int32(atomic.Load(&pendingPreemptSignals)) > 0 {
+		for pendingPreemptSignals.Load() > 0 {
 			osyield()
 		}
 	}