WAN: protect HDLC proto list while insmod/rmmod

WAN: protect protocol list in hdlc.c with RTNL.

Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/drivers/net/wan/hdlc.c b/drivers/net/wan/hdlc.c
index 9a83c9d5b8cf..7f984895b0d5 100644
--- a/drivers/net/wan/hdlc.c
+++ b/drivers/net/wan/hdlc.c
@@ -43,8 +43,7 @@ static const char* version = "HDLC support module revision 1.22";
 
 #undef DEBUG_LINK
 
-static struct hdlc_proto *first_proto = NULL;
-
+static struct hdlc_proto *first_proto;
 
 static int hdlc_change_mtu(struct net_device *dev, int new_mtu)
 {
@@ -314,21 +313,25 @@ void detach_hdlc_protocol(struct net_device *dev)
 
 void register_hdlc_protocol(struct hdlc_proto *proto)
 {
+        rtnl_lock();
         proto->next = first_proto;
         first_proto = proto;
+        rtnl_unlock();
 }
 
 
 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 {
-        struct hdlc_proto **p = &first_proto;
-        while (*p) {
-                if (*p == proto) {
-                        *p = proto->next;
-                        return;
-                }
+        struct hdlc_proto **p;
+
+        rtnl_lock();
+        p = &first_proto;
+        while (*p != proto) {
+                BUG_ON(!*p);
                 p = &((*p)->next);
         }
+        *p = proto->next;
+        rtnl_unlock();
 }