svn commit: r207012 - stable/8/sys/net

[Bjoern A. Zeeb]

Author: bz
Date: Wed Apr 21 19:48:40 2010
New Revision: 207012
URL: http://svn.freebsd.org/changeset/base/207012

Log:
  MFC r206470:
  
    In if_detach_internal() we cannot hold the af_data lock over the
    dom_ifdetach() calls as they might sleep for callout_drain().
    Do as we do in if_attachdomain1() [r121470] and handle
    if_afdata_initialized earlier and call dom_ifdetach() unlocked.
  
    Discussed with:       rwatson

Modified:
  stable/8/sys/net/if.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)
  stable/8/sys/dev/xen/xenpci/   (props changed)
  stable/8/sys/geom/sched/   (props changed)

Modified: stable/8/sys/net/if.c
==============================================================================
--- stable/8/sys/net/if.c	Wed Apr 21 19:47:19 2010	(r207011)
+++ stable/8/sys/net/if.c	Wed Apr 21 19:48:40 2010	(r207012)
@@ -930,14 +930,20 @@ if_detach_internal(struct ifnet *ifp, in
 		devctl_notify("IFNET", ifp->if_xname, "DETACH", NULL);
 	if_delgroups(ifp);
 
+	/*
+	 * We cannot hold the lock over dom_ifdetach calls as they might
+	 * sleep, for example trying to drain a callout, thus open up the
+	 * theoretical race with re-attaching.
+	 */
 	IF_AFDATA_LOCK(ifp);
-	for (dp = domains; ifp->if_afdata_initialized > 0 && dp; dp = dp->dom_next) {
+	i = ifp->if_afdata_initialized;
+	ifp->if_afdata_initialized = 0;
+	IF_AFDATA_UNLOCK(ifp);
+	for (dp = domains; i > 0 && dp; dp = dp->dom_next) {
 		if (dp->dom_ifdetach && ifp->if_afdata[dp->dom_family])
 			(*dp->dom_ifdetach)(ifp,
 			    ifp->if_afdata[dp->dom_family]);
 	}
-	ifp->if_afdata_initialized = 0;
-	IF_AFDATA_UNLOCK(ifp);
 }
 
 #ifdef VIMAGE