From: Keith Randall <khr@golang.org>
Date: Tue, 6 Jan 2015 16:41:55 +0000 (-0800)
Subject: runtime: add comment about channels already handling zero-sized objects correctly.
X-Git-Tag: go1.5beta1~2426
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=ec767c10b30819d907b010a8cfb4831420db7718;p=gostls13.git

runtime: add comment about channels already handling zero-sized objects correctly.

update #9401

Change-Id: I634a772814e7cd066f631a68342e7c3dc9d27e72
Reviewed-on: https://go-review.googlesource.com/2370
Reviewed-by: Russ Cox <rsc@golang.org>
---

diff --git a/src/runtime/chan.go b/src/runtime/chan.go
index e9390d3da4..abe73e70a0 100644
--- a/src/runtime/chan.go
+++ b/src/runtime/chan.go
@@ -46,7 +46,9 @@ func makechan(t *chantype, size int64) *hchan {
 		if size > 0 && elem.size != 0 {
 			c.buf = (*uint8)(add(unsafe.Pointer(c), hchanSize))
 		} else {
-			c.buf = (*uint8)(unsafe.Pointer(c)) // race detector uses this location for synchronization
+			// race detector uses this location for synchronization
+			// Also prevents us from pointing beyond the allocation (see issue 9401).
+			c.buf = (*uint8)(unsafe.Pointer(c))
 		}
 	} else {
 		c = new(hchan)