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Date:      Thu, 18 Apr 2013 10:49:52 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org
Subject:   svn commit: r249619 - stable/9/sys/geom
Message-ID:  <201304181049.r3IAnqxg014292@svn.freebsd.org>
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Author: mav
Date: Thu Apr 18 10:49:52 2013
New Revision: 249619
URL: http://svnweb.freebsd.org/changeset/base/249619

Log:
  MFC r248674:
  Make g_wither_washer() to not loop by itself, but only when there was some
  more topology change done that may require its attention.  Add few missing
  g_do_wither() calls in respective places to signal it.
  
  This fixes potential infinite loop here when some provider is withered, but
  still opened or connected for some reason and so can not be destroyed.  For
  example, see r227009 and r227510.

Modified:
  stable/9/sys/geom/geom_event.c
  stable/9/sys/geom/geom_int.h
  stable/9/sys/geom/geom_subr.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/geom/geom_event.c
==============================================================================
--- stable/9/sys/geom/geom_event.c	Thu Apr 18 10:42:48 2013	(r249618)
+++ stable/9/sys/geom/geom_event.c	Thu Apr 18 10:49:52 2013	(r249619)
@@ -273,21 +273,16 @@ one_event(void)
 void
 g_run_events()
 {
-	int i;
 
 	for (;;) {
 		g_topology_lock();
 		while (one_event())
 			;
 		mtx_assert(&g_eventlock, MA_OWNED);
-		i = g_wither_work;
-		if (i) {
+		if (g_wither_work) {
+			g_wither_work = 0;
 			mtx_unlock(&g_eventlock);
-			while (i) {
-				i = g_wither_washer();
-				g_wither_work = i & 1;
-				i &= 2;
-			}
+			g_wither_washer();
 			g_topology_unlock();
 		} else {
 			g_topology_unlock();

Modified: stable/9/sys/geom/geom_int.h
==============================================================================
--- stable/9/sys/geom/geom_int.h	Thu Apr 18 10:42:48 2013	(r249618)
+++ stable/9/sys/geom/geom_int.h	Thu Apr 18 10:49:52 2013	(r249619)
@@ -65,7 +65,7 @@ void g_do_wither(void);
 /* geom_subr.c */
 extern struct class_list_head g_classes;
 extern char *g_wait_event, *g_wait_sim, *g_wait_up, *g_wait_down;
-int g_wither_washer(void);
+void g_wither_washer(void);
 
 /* geom_io.c */
 void g_io_init(void);

Modified: stable/9/sys/geom/geom_subr.c
==============================================================================
--- stable/9/sys/geom/geom_subr.c	Thu Apr 18 10:42:48 2013	(r249618)
+++ stable/9/sys/geom/geom_subr.c	Thu Apr 18 10:49:52 2013	(r249619)
@@ -434,20 +434,16 @@ g_wither_geom_close(struct g_geom *gp, i
 
 /*
  * This function is called (repeatedly) until we cant wash away more
- * withered bits at present.  Return value contains two bits.  Bit 0
- * set means "withering stuff we can't wash now", bit 1 means "call
- * me again, there may be stuff I didn't get the first time around.
+ * withered bits at present.
  */
-int
+void
 g_wither_washer()
 {
 	struct g_class *mp;
 	struct g_geom *gp, *gp2;
 	struct g_provider *pp, *pp2;
 	struct g_consumer *cp, *cp2;
-	int result;
 
-	result = 0;
 	g_topology_assert();
 	LIST_FOREACH(mp, &g_classes, class) {
 		LIST_FOREACH_SAFE(gp, &mp->geom, geom, gp2) {
@@ -456,35 +452,25 @@ g_wither_washer()
 					continue;
 				if (LIST_EMPTY(&pp->consumers))
 					g_destroy_provider(pp);
-				else
-					result |= 1;
 			}
 			if (!(gp->flags & G_GEOM_WITHER))
 				continue;
 			LIST_FOREACH_SAFE(pp, &gp->provider, provider, pp2) {
 				if (LIST_EMPTY(&pp->consumers))
 					g_destroy_provider(pp);
-				else
-					result |= 1;
 			}
 			LIST_FOREACH_SAFE(cp, &gp->consumer, consumer, cp2) {
-				if (cp->acr || cp->acw || cp->ace) {
-					result |= 1;
+				if (cp->acr || cp->acw || cp->ace)
 					continue;
-				}
 				if (cp->provider != NULL)
 					g_detach(cp);
 				g_destroy_consumer(cp);
-				result |= 2;
 			}
 			if (LIST_EMPTY(&gp->provider) &&
 			    LIST_EMPTY(&gp->consumer))
 				g_destroy_geom(gp);
-			else
-				result |= 1;
 		}
 	}
-	return (result);
 }
 
 struct g_consumer *
@@ -772,9 +758,9 @@ g_detach(struct g_consumer *cp)
 	pp = cp->provider;
 	LIST_REMOVE(cp, consumers);
 	cp->provider = NULL;
-	if (pp->geom->flags & G_GEOM_WITHER)
-		g_do_wither();
-	else if (pp->flags & G_PF_WITHER)
+	if ((cp->geom->flags & G_GEOM_WITHER) ||
+	    (pp->geom->flags & G_GEOM_WITHER) ||
+	    (pp->flags & G_PF_WITHER))
 		g_do_wither();
 	redo_rank(cp->geom);
 }
@@ -873,6 +859,9 @@ g_access(struct g_consumer *cp, int dcr,
 		if (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)
 			KASSERT(pp->sectorsize > 0,
 			    ("Provider %s lacks sectorsize", pp->name));
+		if ((cp->geom->flags & G_GEOM_WITHER) &&
+		    cp->acr == 0 && cp->acw == 0 && cp->ace == 0)
+			g_do_wither();
 	}
 	return (error);
 }

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