packet: Add helpers to register/unregister ->prot_hook

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 59 insertions, 44 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 461b16fa1c52..bb281bf330aa 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -222,6 +222,55 @@ struct packet_skb_cb {
 
 #define PACKET_SKB_CB(__skb)    ((struct packet_skb_cb *)((__skb)->cb))
 
+static inline struct packet_sock *pkt_sk(struct sock *sk)
+{
+        return (struct packet_sock *)sk;
+}
+
+/* register_prot_hook must be invoked with the po->bind_lock held,
+ * or from a context in which asynchronous accesses to the packet
+ * socket is not possible (packet_create()).
+ */
+static void register_prot_hook(struct sock *sk)
+{
+        struct packet_sock *po = pkt_sk(sk);
+        if (!po->running) {
+                dev_add_pack(&po->prot_hook);
+                sock_hold(sk);
+                po->running = 1;
+        }
+}
+
+/* {,__}unregister_prot_hook() must be invoked with the po->bind_lock
+ * held.   If the sync parameter is true, we will temporarily drop
+ * the po->bind_lock and do a synchronize_net to make sure no
+ * asynchronous packet processing paths still refer to the elements
+ * of po->prot_hook.  If the sync parameter is false, it is the
+ * callers responsibility to take care of this.
+ */
+static void __unregister_prot_hook(struct sock *sk, bool sync)
+{
+        struct packet_sock *po = pkt_sk(sk);
+
+        po->running = 0;
+        __dev_remove_pack(&po->prot_hook);
+        __sock_put(sk);
+
+        if (sync) {
+                spin_unlock(&po->bind_lock);
+                synchronize_net();
+                spin_lock(&po->bind_lock);
+        }
+}
+
+static void unregister_prot_hook(struct sock *sk, bool sync)
+{
+        struct packet_sock *po = pkt_sk(sk);
+
+        if (po->running)
+                __unregister_prot_hook(sk, sync);
+}
+
 static inline __pure struct page *pgv_to_page(void *addr)
 {
         if (is_vmalloc_addr(addr))
@@ -324,11 +373,6 @@ static inline void packet_increment_head(struct packet_ring_buffer *buff)
         buff->head = buff->head != buff->frame_max ? buff->head+1 : 0;
 }
 
-static inline struct packet_sock *pkt_sk(struct sock *sk)
-{
-        return (struct packet_sock *)sk;
-}
-
 static void packet_sock_destruct(struct sock *sk)
 {
         skb_queue_purge(&sk->sk_error_queue);
@@ -1337,15 +1381,7 @@ static int packet_release(struct socket *sock)
         spin_unlock_bh(&net->packet.sklist_lock);
 
         spin_lock(&po->bind_lock);
-        if (po->running) {
-                /*
-                 * Remove from protocol table
-                 */
-                po->running = 0;
-                po->num = 0;
-                __dev_remove_pack(&po->prot_hook);
-                __sock_put(sk);
-        }
+        unregister_prot_hook(sk, false);
         if (po->prot_hook.dev) {
                 dev_put(po->prot_hook.dev);
                 po->prot_hook.dev = NULL;
@@ -1392,15 +1428,7 @@ static int packet_do_bind(struct sock *sk, struct net_device *dev, __be16 protoc
         lock_sock(sk);
 
         spin_lock(&po->bind_lock);
-        if (po->running) {
-                __sock_put(sk);
-                po->running = 0;
-                po->num = 0;
-                spin_unlock(&po->bind_lock);
-                dev_remove_pack(&po->prot_hook);
-                spin_lock(&po->bind_lock);
-        }
-
+        unregister_prot_hook(sk, true);
         po->num = protocol;
         po->prot_hook.type = protocol;
         if (po->prot_hook.dev)
@@ -1413,9 +1441,7 @@ static int packet_do_bind(struct sock *sk, struct net_device *dev, __be16 protoc
                 goto out_unlock;
 
         if (!dev || (dev->flags & IFF_UP)) {
-                dev_add_pack(&po->prot_hook);
-                sock_hold(sk);
-                po->running = 1;
+                register_prot_hook(sk);
         } else {
                 sk->sk_err = ENETDOWN;
                 if (!sock_flag(sk, SOCK_DEAD))
@@ -1542,9 +1568,7 @@ static int packet_create(struct net *net, struct socket *sock, int protocol,
 
         if (proto) {
                 po->prot_hook.type = proto;
-                dev_add_pack(&po->prot_hook);
-                sock_hold(sk);
-                po->running = 1;
+                register_prot_hook(sk);
         }
 
         spin_lock_bh(&net->packet.sklist_lock);
@@ -2240,9 +2264,7 @@ static int packet_notifier(struct notifier_block *this, unsigned long msg, void
                         if (dev->ifindex == po->ifindex) {
                                 spin_lock(&po->bind_lock);
                                 if (po->running) {
-                                        __dev_remove_pack(&po->prot_hook);
-                                        __sock_put(sk);
-                                        po->running = 0;
+                                        __unregister_prot_hook(sk, false);
                                         sk->sk_err = ENETDOWN;
                                         if (!sock_flag(sk, SOCK_DEAD))
                                                 sk->sk_error_report(sk);
@@ -2259,11 +2281,8 @@ static int packet_notifier(struct notifier_block *this, unsigned long msg, void
                 case NETDEV_UP:
                         if (dev->ifindex == po->ifindex) {
                                 spin_lock(&po->bind_lock);
-                                if (po->num && !po->running) {
-                                        dev_add_pack(&po->prot_hook);
-                                        sock_hold(sk);
-                                        po->running = 1;
-                                }
+                                if (po->num)
+                                        register_prot_hook(sk);
                                 spin_unlock(&po->bind_lock);
                         }
                         break;
@@ -2530,10 +2549,8 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req,
         was_running = po->running;
         num = po->num;
         if (was_running) {
-                __dev_remove_pack(&po->prot_hook);
                 po->num = 0;
-                po->running = 0;
-                __sock_put(sk);
+                __unregister_prot_hook(sk, false);
         }
         spin_unlock(&po->bind_lock);
 
@@ -2564,11 +2581,9 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req,
         mutex_unlock(&po->pg_vec_lock);
 
         spin_lock(&po->bind_lock);
-        if (was_running && !po->running) {
-                sock_hold(sk);
-                po->running = 1;
+        if (was_running) {
                 po->num = num;
-                dev_add_pack(&po->prot_hook);
+                register_prot_hook(sk);
         }
         spin_unlock(&po->bind_lock);