From: Michael Pratt <mpratt@google.com>
Date: Tue, 7 Jul 2020 21:55:40 +0000 (-0400)
Subject: runtime: drop redundant gcBlackenEnabled reset
X-Git-Tag: go1.16beta1~562
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=db185e543fe471c522790b7d93291e786dc54a84;p=gostls13.git

runtime: drop redundant gcBlackenEnabled reset

This reset of gcBlackenEnabled is a no-op because it was already reset
almost immediately before in gcMarkDone, which is the only caller of
gcMarkTermination.

Adjust the comment to clarify setGCPhase a bit more. We are coming from
_GCmark, so write barriers are already enabled.

Change-Id: Ieac2dadf33c3c5a44e8a25a499dea8cfe03b8d73
Reviewed-on: https://go-review.googlesource.com/c/go/+/241357
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
---

diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 65ac654b14..c42c7fbd29 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -1558,10 +1558,10 @@ top:
 	gcMarkTermination(nextTriggerRatio)
 }
 
+// World must be stopped and mark assists and background workers must be
+// disabled.
 func gcMarkTermination(nextTriggerRatio float64) {
-	// World is stopped.
-	// Start marktermination which includes enabling the write barrier.
-	atomic.Store(&gcBlackenEnabled, 0)
+	// Start marktermination (write barrier remains enabled for now).
 	setGCPhase(_GCmarktermination)
 
 	work.heap1 = memstats.heap_live