[XFRM]: Handle device down/unregister events.

This patch makes us prune all bundles containing devices being shut down
or removed.  It also merges two existing functions that walk bundles
looking for things to delete.

net/xfrm/xfrm_policy.c

@@ -19,6 +19,8 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
+#include <linux/notifier.h>
+#include <linux/netdevice.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
 
@@ -1022,7 +1024,8 @@ static struct dst_entry *xfrm_negative_advice(struct dst_entry *dst)
 	return dst;
 }
 
-static void __xfrm_garbage_collect(void)
+static void xfrm_prune_bundles(int (*func)(struct dst_entry *, void *),
+			      void *data)
 {
 	int i;
 	struct xfrm_policy *pol;
@@ -1034,7 +1037,7 @@ static void __xfrm_garbage_collect(void)
 			write_lock(&pol->lock);
 			dstp = &pol->bundles;
 			while ((dst=*dstp) != NULL) {
-				if (atomic_read(&dst->__refcnt) == 0) {
+				if (func(dst, data)) {
 					*dstp = dst->next;
 					dst->next = gc_list;
 					gc_list = dst;
@@ -1054,8 +1057,20 @@ static void __xfrm_garbage_collect(void)
 	}
 }
 
-static int bundle_depends_on(struct dst_entry *dst, struct xfrm_state *x)
+static int unused_dst(struct dst_entry *dst, void *data)
 {
+	return !atomic_read(&dst->__refcnt);
+}
+
+static void __xfrm_garbage_collect(void)
+{
+	xfrm_prune_bundles(unused_dst, NULL);
+}
+
+static int bundle_depends_on(struct dst_entry *dst, void *data)
+{
+	struct xfrm_state *x = data;
+
 	do {
 		if (dst->xfrm == x)
 			return 1;
@@ -1065,35 +1080,7 @@ static int bundle_depends_on(struct dst_entry *dst, struct xfrm_state *x)
 
 int xfrm_flush_bundles(struct xfrm_state *x)
 {
-	int i;
-	struct xfrm_policy *pol;
-	struct dst_entry *dst, **dstp, *gc_list = NULL;
-
-	read_lock_bh(&xfrm_policy_lock);
-	for (i=0; i<2*XFRM_POLICY_MAX; i++) {
-		for (pol = xfrm_policy_list[i]; pol; pol = pol->next) {
-			write_lock(&pol->lock);
-			dstp = &pol->bundles;
-			while ((dst=*dstp) != NULL) {
-				if (bundle_depends_on(dst, x)) {
-					*dstp = dst->next;
-					dst->next = gc_list;
-					gc_list = dst;
-				} else {
-					dstp = &dst->next;
-				}
-			}
-			write_unlock(&pol->lock);
-		}
-	}
-	read_unlock_bh(&xfrm_policy_lock);
-
-	while (gc_list) {
-		dst = gc_list;
-		gc_list = dst->next;
-		dst_free(dst);
-	}
-
+	xfrm_prune_bundles(bundle_depends_on, x);
 	return 0;
 }
 
@@ -1216,6 +1203,35 @@ void xfrm_policy_put_afinfo(struct xfrm_policy_afinfo *afinfo)
 	read_unlock(&afinfo->lock);
 }
 
+static int bundle_has_dev(struct dst_entry *dst, void *data)
+{
+	struct net_device *dev = data;
+
+	do {
+		if (dst->dev == dev)
+			return 1;
+	} while ((dst = dst->child) != NULL);
+	return 0;
+}
+
+static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct net_device *dev = ptr;
+
+	switch (event) {
+	case NETDEV_UNREGISTER:
+	case NETDEV_DOWN:
+		xfrm_prune_bundles(bundle_has_dev, dev);
+	}
+	return NOTIFY_DONE;
+}
+
+struct notifier_block xfrm_dev_notifier = {
+	xfrm_dev_event,
+	NULL,
+	0
+};
+
 void __init xfrm_policy_init(void)
 {
 	xfrm_dst_cache = kmem_cache_create("xfrm_dst_cache",
@@ -1226,6 +1242,7 @@ void __init xfrm_policy_init(void)
 		panic("XFRM: failed to allocate xfrm_dst_cache\n");
 
 	INIT_WORK(&xfrm_policy_gc_work, xfrm_policy_gc_task, NULL);
+	register_netdevice_notifier(&xfrm_dev_notifier);
 }
 
 void __init xfrm_init(void)