runtime: add test for signalM

For #10958, #24543.

Change-Id: Ib009a83fe02bc623894f4908fe8f6b266382ba95
Reviewed-on: https://go-review.googlesource.com/c/go/+/201404
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/runtime/export_unix_test.go b/src/runtime/export_unix_test.go
index eecdfb7eb2..3f8bff619d 100644
--- a/src/runtime/export_unix_test.go
+++ b/src/runtime/export_unix_test.go
@@ -17,3 +17,42 @@ func Sigisblocked(i int) bool {
 	sigprocmask(_SIG_SETMASK, nil, &sigmask)
 	return sigismember(&sigmask, i)
 }
+
+type M = m
+
+var waitForSigusr1 struct {
+	park note
+	mp   *m
+}
+
+// WaitForSigusr1 blocks until a SIGUSR1 is received. It calls ready
+// when it is set up to receive SIGUSR1. The ready function should
+// cause a SIGUSR1 to be sent.
+//
+// Once SIGUSR1 is received, it returns the ID of the current M and
+// the ID of the M the SIGUSR1 was received on. If no SIGUSR1 is
+// received for timeoutNS nanoseconds, it returns -1.
+func WaitForSigusr1(ready func(mp *M), timeoutNS int64) (int64, int64) {
+	mp := getg().m
+	testSigusr1 = func(gp *g) bool {
+		waitForSigusr1.mp = gp.m
+		notewakeup(&waitForSigusr1.park)
+		return true
+	}
+	ready(mp)
+	ok := notetsleepg(&waitForSigusr1.park, timeoutNS)
+	noteclear(&waitForSigusr1.park)
+	gotM := waitForSigusr1.mp
+	waitForSigusr1.mp = nil
+	testSigusr1 = nil
+
+	if !ok {
+		return -1, -1
+	}
+	return mp.id, gotM.id
+}
+
+// SendSigusr1 sends SIGUSR1 to mp.
+func SendSigusr1(mp *M) {
+	signalM(mp, _SIGUSR1)
+}