svn commit: r316867 - head/sys/geom/mirror

[Mark Johnston]

Author: markj
Date: Fri Apr 14 17:08:37 2017
New Revision: 316867
URL: https://svnweb.freebsd.org/changeset/base/316867

Log:
  Don't set the mirror GEOM softc to NULL in g_mirror_destroy().
  
  At this point we have not rendezvous'ed with the mirror worker thread, and
  I/O may still be in flight. Various I/O completion paths expect to be able
  to obtain a reference to the mirror softc from the GEOM, so setting it to
  NULL may result in various NULL pointer dereferences if the mirror is
  stopped with -f or the kernel is shut down while a mirror is
  synchronizing. The worker thread will clear the softc pointer before
  exiting.
  
  Tested by:	pho
  MFC after:	2 weeks
  Sponsored by:	Dell EMC Isilon

Modified:
  head/sys/geom/mirror/g_mirror.c

Modified: head/sys/geom/mirror/g_mirror.c
==============================================================================
--- head/sys/geom/mirror/g_mirror.c	Fri Apr 14 17:03:32 2017	(r316866)
+++ head/sys/geom/mirror/g_mirror.c	Fri Apr 14 17:08:37 2017	(r316867)
@@ -3076,15 +3076,8 @@ g_mirror_destroy(struct g_mirror_softc *
 		}
 	}
 
-	g_topology_lock();
-	if (sc->sc_geom->softc == NULL) {
-		g_topology_unlock();
+	if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0)
 		return (0);
-	}
-	sc->sc_geom->softc = NULL;
-	sc->sc_sync.ds_geom->softc = NULL;
-	g_topology_unlock();
-
 	sc->sc_flags |= G_MIRROR_DEVICE_FLAG_DESTROY;
 	sc->sc_flags |= G_MIRROR_DEVICE_FLAG_WAIT;
 	G_MIRROR_DEBUG(4, "%s: Waking up %p.", __func__, sc);