[AX.25]: Reference counting for AX.25 routes.

In the past routes could be freed even though the were possibly in use ...

Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 23 insertions, 49 deletions

diff --git a/net/ax25/ax25_ip.c b/net/ax25/ax25_ip.c
index 9be5c15e63d3..136c3aefa9de 100644
--- a/net/ax25/ax25_ip.c
+++ b/net/ax25/ax25_ip.c
@@ -103,11 +103,13 @@ int ax25_rebuild_header(struct sk_buff *skb)
 {
         struct sk_buff *ourskb;
         unsigned char *bp  = skb->data;
-        struct net_device *dev;
+        ax25_route *route;
+        struct net_device *dev = NULL;
         ax25_address *src, *dst;
+        ax25_digi *digipeat = NULL;
         ax25_dev *ax25_dev;
-        ax25_route _route, *route = &_route;
         ax25_cb *ax25;
+        char ip_mode = ' ';
 
         dst = (ax25_address *)(bp + 1);
         src = (ax25_address *)(bp + 8);
@@ -115,8 +117,12 @@ int ax25_rebuild_header(struct sk_buff *skb)
         if (arp_find(bp + 1, skb))
                 return 1;
 
-        route = ax25_rt_find_route(route, dst, NULL);
-        dev      = route->dev;
+        route = ax25_get_route(dst, NULL);
+        if (route) {
+                digipeat = route->digipeat;
+                dev = route->dev;
+                ip_mode = route->ip_mode;
+        };
 
         if (dev == NULL)
                 dev = skb->dev;
@@ -126,7 +132,7 @@ int ax25_rebuild_header(struct sk_buff *skb)
         }
 
         if (bp[16] == AX25_P_IP) {
-                if (route->ip_mode == 'V' || (route->ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
+                if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
                         /*
                          *      We copy the buffer and release the original thereby
                          *      keeping it straight
@@ -172,7 +178,7 @@ int ax25_rebuild_header(struct sk_buff *skb)
                             ourskb, 
                             ax25_dev->values[AX25_VALUES_PACLEN], 
                             &src_c,
-                            &dst_c, route->digipeat, dev);
+                            &dst_c, digipeat, dev);
                         if (ax25) {
                                 ax25_cb_put(ax25);
                         }
@@ -190,7 +196,7 @@ int ax25_rebuild_header(struct sk_buff *skb)
 
         skb_pull(skb, AX25_KISS_HEADER_LEN);
 
-        if (route->digipeat != NULL) {
+        if (digipeat != NULL) {
                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
                         kfree_skb(skb);
                         goto put;
@@ -202,7 +208,8 @@ int ax25_rebuild_header(struct sk_buff *skb)
         ax25_queue_xmit(skb, dev);
 
 put:
-        ax25_put_route(route);
+        if (route)
+                ax25_put_route(route);
 
         return 1;
 }
diff --git a/net/ax25/ax25_route.c b/net/ax25/ax25_route.c
index 5ac98250797b..51b7bdaf27eb 100644
--- a/net/ax25/ax25_route.c
+++ b/net/ax25/ax25_route.c
@@ -41,8 +41,6 @@
 static ax25_route *ax25_route_list;
 static DEFINE_RWLOCK(ax25_route_lock);
 
-static ax25_route *ax25_get_route(ax25_address *, struct net_device *);
-
 void ax25_rt_device_down(struct net_device *dev)
 {
         ax25_route *s, *t, *ax25_rt;
@@ -115,7 +113,7 @@ static int ax25_rt_add(struct ax25_routes_struct *route)
                 return -ENOMEM;
         }
 
-        atomic_set(&ax25_rt->ref, 0);
+        atomic_set(&ax25_rt->refcount, 1);
         ax25_rt->callsign     = route->dest_addr;
         ax25_rt->dev          = ax25_dev->dev;
         ax25_rt->digipeat     = NULL;
@@ -140,23 +138,10 @@ static int ax25_rt_add(struct ax25_routes_struct *route)
         return 0;
 }
 
-static void ax25_rt_destroy(ax25_route *ax25_rt)
+void __ax25_put_route(ax25_route *ax25_rt)
 {
-        if (atomic_read(&ax25_rt->ref) == 0) {
-                kfree(ax25_rt->digipeat);
-                kfree(ax25_rt);
-                return;
-        }
-
-        /*
-         * Uh...  Route is still in use; we can't yet destroy it.  Retry later.
-         */
-        init_timer(&ax25_rt->timer);
-        ax25_rt->timer.data     = (unsigned long) ax25_rt;
-        ax25_rt->timer.function = (void *) ax25_rt_destroy;
-        ax25_rt->timer.expires  = jiffies + 5 * HZ;
-
-        add_timer(&ax25_rt->timer);
+        kfree(ax25_rt->digipeat);
+        kfree(ax25_rt);
 }
 
 static int ax25_rt_del(struct ax25_routes_struct *route)
@@ -177,12 +162,12 @@ static int ax25_rt_del(struct ax25_routes_struct *route)
                     ax25cmp(&route->dest_addr, &s->callsign) == 0) {
                         if (ax25_route_list == s) {
                                 ax25_route_list = s->next;
-                                ax25_rt_destroy(s);
+                                ax25_put_route(s);
                         } else {
                                 for (t = ax25_route_list; t != NULL; t = t->next) {
                                         if (t->next == s) {
                                                 t->next = s->next;
-                                                ax25_rt_destroy(s);
+                                                ax25_put_route(s);
                                                 break;
                                         }
                                 }
@@ -362,7 +347,7 @@ struct file_operations ax25_route_fops = {
  *
  *      Only routes with a reference count of zero can be destroyed.
  */
-static ax25_route *ax25_get_route(ax25_address *addr, struct net_device *dev)
+ax25_route *ax25_get_route(ax25_address *addr, struct net_device *dev)
 {
         ax25_route *ax25_spe_rt = NULL;
         ax25_route *ax25_def_rt = NULL;
@@ -392,7 +377,7 @@ static ax25_route *ax25_get_route(ax25_address *addr, struct net_device *dev)
                 ax25_rt = ax25_spe_rt;
 
         if (ax25_rt != NULL)
-                atomic_inc(&ax25_rt->ref);
+                ax25_hold_route(ax25_rt);
 
         read_unlock(&ax25_route_lock);
 
@@ -467,24 +452,6 @@ put:
         return 0;
 }
 
-ax25_route *ax25_rt_find_route(ax25_route * route, ax25_address *addr,
-        struct net_device *dev)
-{
-        ax25_route *ax25_rt;
-
-        if ((ax25_rt = ax25_get_route(addr, dev)))
-                return ax25_rt;
-
-        route->next     = NULL;
-        atomic_set(&route->ref, 1);
-        route->callsign = *addr;
-        route->dev      = dev;
-        route->digipeat = NULL;
-        route->ip_mode  = ' ';
-
-        return route;
-}
-
 struct sk_buff *ax25_rt_build_path(struct sk_buff *skb, ax25_address *src,
         ax25_address *dest, ax25_digi *digi)
 {