From caa149f73da050377c8009ae4b7a565d6a36b3b9 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Tue, 6 Apr 2010 16:50:27 -0700
Subject: [PATCH] net: use chan bool instead of chan *netFD to avoid cycle

The cycle is *netFD -> cw chanl *netFD in struct ->
same *netFD in channel read buffer.

Because channels are finalized, the cycle makes them
uncollectable.  A better fix is to make channels not
finalized anymore, and that will happen, but this is
an easy, reasonable workaround until then.

Another good fix would be to zero the channel receive
buffer entry after the receive.  That too will happen.

R=r
CC=golang-dev
https://golang.org/cl/875043
---
 src/pkg/net/fd.go | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/pkg/net/fd.go b/src/pkg/net/fd.go
index 28e85be2a3..02f7319cbf 100644
--- a/src/pkg/net/fd.go
+++ b/src/pkg/net/fd.go
@@ -26,8 +26,8 @@ type netFD struct {
 	family  int
 	proto   int
 	sysfile *os.File
-	cr      chan *netFD
-	cw      chan *netFD
+	cr      chan bool
+	cw      chan bool
 	net     string
 	laddr   Addr
 	raddr   Addr
@@ -122,9 +122,9 @@ func (s *pollServer) AddFD(fd *netFD, mode int) {
 	if intfd < 0 {
 		// fd closed underfoot
 		if mode == 'r' {
-			fd.cr <- fd
+			fd.cr <- true
 		} else {
-			fd.cw <- fd
+			fd.cw <- true
 		}
 		return
 	}
@@ -166,12 +166,12 @@ func (s *pollServer) WakeFD(fd *netFD, mode int) {
 	if mode == 'r' {
 		for fd.ncr > 0 {
 			fd.ncr--
-			fd.cr <- fd
+			fd.cr <- true
 		}
 	} else {
 		for fd.ncw > 0 {
 			fd.ncw--
-			fd.cw <- fd
+			fd.cw <- true
 		}
 	}
 }
@@ -312,8 +312,8 @@ func newFD(fd, family, proto int, net string, laddr, raddr Addr) (f *netFD, err
 		rs = raddr.String()
 	}
 	f.sysfile = os.NewFile(fd, net+":"+ls+"->"+rs)
-	f.cr = make(chan *netFD, 1)
-	f.cw = make(chan *netFD, 1)
+	f.cr = make(chan bool, 1)
+	f.cw = make(chan bool, 1)
 	return f, nil
 }
 
-- 
2.50.0