runtime: hold traceAcquire across casgstatus in injectglist

mknyszek · mknyszek · commit f025d19e7b3f · 2025-01-08T09:25:53.000-08:00
Currently injectglist emits all the trace events before actually calling casgstatus on each goroutine. This is a problem, since tracing can observe an inconsistent state (gstatus does not match tracer's 'emitted an event' state). This change fixes the problem by having injectglist do what every other scheduler function does, and that's wrap each call to casgstatus in traceAcquire/traceRelease. Fixes #70883. Change-Id: I857e96cec01688013597e8efc0c4c3d0b72d3a70 Reviewed-on: https://go-review.googlesource.com/c/go/+/638558 Reviewed-by: Michael Pratt <mpratt@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
@@ -3894,23 +3894,23 @@ func injectglist(glist *gList) {
 	if glist.empty() {
 		return
 	}
-	trace := traceAcquire()
-	if trace.ok() {
-		for gp := glist.head.ptr(); gp != nil; gp = gp.schedlink.ptr() {
-			trace.GoUnpark(gp, 0)
-		}
-		traceRelease(trace)
-	}
 
 	// Mark all the goroutines as runnable before we put them
 	// on the run queues.
 	head := glist.head.ptr()
 	var tail *g
 	qsize := 0
+	trace := traceAcquire()
 	for gp := head; gp != nil; gp = gp.schedlink.ptr() {
 		tail = gp
 		qsize++
 		casgstatus(gp, _Gwaiting, _Grunnable)
+		if trace.ok() {
+			trace.GoUnpark(gp, 0)
+		}
+	}
+	if trace.ok() {
+		traceRelease(trace)
 	}
 
 	// Turn the gList into a gQueue.
