From: Dmitriy Vyukov <dvyukov@google.com>
Date: Sat, 27 Jul 2013 09:46:40 +0000 (+0400)
Subject: runtime: fix potential deadlock in netpoll on windows
X-Git-Tag: go1.2rc2~929
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=91d35ad1b86bd9835596704e8ecf1856d3851390;p=gostls13.git

runtime: fix potential deadlock in netpoll on windows
If netpoll has been told to block, it must not return with nil,
otherwise scheduler assumes that netpoll is disabled.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/11920044
---

diff --git a/src/pkg/runtime/netpoll_windows.c b/src/pkg/runtime/netpoll_windows.c
index 52ba7e46e6..972f1c30ef 100644
--- a/src/pkg/runtime/netpoll_windows.c
+++ b/src/pkg/runtime/netpoll_windows.c
@@ -71,6 +71,8 @@ runtime·netpoll(bool block)
 
 	if(iocphandle == INVALID_HANDLE_VALUE)
 		return nil;
+	gp = nil;
+retry:
 	o = nil;
 	errno = 0;
 	qty = 0;
@@ -104,7 +106,8 @@ runtime·netpoll(bool block)
 	}
 	o->errno = errno;
 	o->qty = qty;
-	gp = nil;
 	runtime·netpollready(&gp, (void*)o->runtimeCtx, mode);
+	if(block && gp == nil)
+		goto retry;
 	return gp;
 }