code review 12418043: net: add special netFD mutex

src/pkg/net/sockoptip_linux.go

 // Copyright 2011 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
         "os"
         "syscall"
 )
 
 func setIPv4MulticastInterface(fd *netFD, ifi *Interface) error {
         var v int32
         if ifi != nil {
                 v = int32(ifi.Index)
         }
         mreq := &syscall.IPMreqn{Ifindex: v}
-        if err := fd.incref(false); err != nil {
+        if err := fd.incref(); err != nil {
                 return err
         }
         defer fd.decref()
         return os.NewSyscallError("setsockopt", syscall.SetsockoptIPMreqn(fd.sysfd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, mreq))
 }
 
 func setIPv4MulticastLoopback(fd *netFD, v bool) error {
-        if err := fd.incref(false); err != nil {
+        if err := fd.incref(); err != nil {
                 return err
         }
         defer fd.decref()
         return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, boolint(v)))
 }