From 6b4dcf19fa493905689dedc27f2232b74c366057 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Tue, 28 Jul 2020 20:02:57 +0000
Subject: [PATCH] runtime: hold sched.lock over globrunqputbatch in
 runqputbatch

globrunqputbatch should never be called without sched.lock held.
runqputbatch's documentation even says it may acquire sched.lock in
order to call it.

Fixes #40457.

Change-Id: I5421b64f1da3a6087dfebbef7203db0c95d213a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/245377
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---
 src/runtime/proc.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index ed1aa1c194..035822216d 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -5225,7 +5225,9 @@ func runqputbatch(pp *p, q *gQueue, qsize int) {
 
 	atomic.StoreRel(&pp.runqtail, t)
 	if !q.empty() {
+		lock(&sched.lock)
 		globrunqputbatch(q, int32(qsize))
+		unlock(&sched.lock)
 	}
 }