[dev.link] all: merge branch 'master' into dev.linkdev.link

Clean merge.

Change-Id: Ia7b2808bc649790198d34c226a61d9e569084dc5

1 files changed, 29 insertions, 7 deletions

diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index a3d6f34c88..bf4a319b37 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -335,6 +335,10 @@ func doSigPreempt(gp *g, ctxt *sigctxt) {
 	// Acknowledge the preemption.
 	atomic.Xadd(&gp.m.preemptGen, 1)
 	atomic.Store(&gp.m.signalPending, 0)
+
+	if GOOS == "darwin" {
+		atomic.Xadd(&pendingPreemptSignals, -1)
+	}
 }
 
 const preemptMSupported = true
@@ -356,7 +360,18 @@ func preemptM(mp *m) {
 		// required).
 		return
 	}
+
+	// On Darwin, don't try to preempt threads during exec.
+	// Issue #41702.
+	if GOOS == "darwin" {
+		execLock.rlock()
+	}
+
 	if atomic.Cas(&mp.signalPending, 0, 1) {
+		if GOOS == "darwin" {
+			atomic.Xadd(&pendingPreemptSignals, 1)
+		}
+
 		// If multiple threads are preempting the same M, it may send many
 		// signals to the same M such that it hardly make progress, causing
 		// live-lock problem. Apparently this could happen on darwin. See
@@ -364,6 +379,10 @@ func preemptM(mp *m) {
 		// Only send a signal if there isn't already one pending.
 		signalM(mp, sigPreempt)
 	}
+
+	if GOOS == "darwin" {
+		execLock.runlock()
+	}
 }
 
 // sigFetchG fetches the value of G safely when running in a signal handler.
@@ -424,6 +443,9 @@ func sigtrampgo(sig uint32, info *siginfo, ctx unsafe.Pointer) {
 			// no non-Go signal handler for sigPreempt.
 			// The default behavior for sigPreempt is to ignore
 			// the signal, so badsignal will be a no-op anyway.
+			if GOOS == "darwin" {
+				atomic.Xadd(&pendingPreemptSignals, -1)
+			}
 			return
 		}
 		c.fixsigcode(sig)
@@ -482,14 +504,14 @@ func adjustSignalStack(sig uint32, mp *m, gsigStack *gsignalStack) bool {
 	sigaltstack(nil, &st)
 	if st.ss_flags&_SS_DISABLE != 0 {
 		setg(nil)
-		needm(0)
+		needm()
 		noSignalStack(sig)
 		dropm()
 	}
 	stsp := uintptr(unsafe.Pointer(st.ss_sp))
 	if sp < stsp || sp >= stsp+st.ss_size {
 		setg(nil)
-		needm(0)
+		needm()
 		sigNotOnStack(sig)
 		dropm()
 	}
@@ -929,7 +951,7 @@ func badsignal(sig uintptr, c *sigctxt) {
 		exit(2)
 		*(*uintptr)(unsafe.Pointer(uintptr(123))) = 2
 	}
-	needm(0)
+	needm()
 	if !sigsend(uint32(sig)) {
 		// A foreign thread received the signal sig, and the
 		// Go code does not want to handle it.
@@ -1009,15 +1031,15 @@ func sigfwdgo(sig uint32, info *siginfo, ctx unsafe.Pointer) bool {
 	return true
 }
 
-// msigsave saves the current thread's signal mask into mp.sigmask.
+// sigsave saves the current thread's signal mask into *p.
 // This is used to preserve the non-Go signal mask when a non-Go
 // thread calls a Go function.
 // This is nosplit and nowritebarrierrec because it is called by needm
 // which may be called on a non-Go thread with no g available.
 //go:nosplit
 //go:nowritebarrierrec
-func msigsave(mp *m) {
-	sigprocmask(_SIG_SETMASK, nil, &mp.sigmask)
+func sigsave(p *sigset) {
+	sigprocmask(_SIG_SETMASK, nil, p)
 }
 
 // msigrestore sets the current thread's signal mask to sigmask.
@@ -1089,7 +1111,7 @@ func minitSignalStack() {
 // thread's signal mask. When this is called all signals have been
 // blocked for the thread.  This starts with m.sigmask, which was set
 // either from initSigmask for a newly created thread or by calling
-// msigsave if this is a non-Go thread calling a Go function. It
+// sigsave if this is a non-Go thread calling a Go function. It
 // removes all essential signals from the mask, thus causing those
 // signals to not be blocked. Then it sets the thread's signal mask.
 // After this is called the thread can receive signals.