tcp: Fix a connect() race with timewait sockets

[deliverable/linux.git] / net / ipv4 / inet_timewait_sock.c

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 0fdf45e4c90c8c8475cfd28feb9830d65ebfc204..bf4b1e2a4305e49d45b1fbaa32a8210febfff0ba 100644 (file)
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -29,12 +29,29 @@ int inet_twsk_unhash(struct inet_timewait_sock *tw)
        return 1;
 }
 
+/*
+ * unhash a timewait socket from bind hash
+ * lock must be hold by caller
+ */
+int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
+                         struct inet_hashinfo *hashinfo)
+{
+       struct inet_bind_bucket *tb = tw->tw_tb;
+
+       if (!tb)
+               return 0;
+
+       __hlist_del(&tw->tw_bind_node);
+       tw->tw_tb = NULL;
+       inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+       return 1;
+}
+
 /* Must be called with locally disabled BHs. */
 static void __inet_twsk_kill(struct inet_timewait_sock *tw,
                             struct inet_hashinfo *hashinfo)
 {
        struct inet_bind_hashbucket *bhead;
-       struct inet_bind_bucket *tb;
        int refcnt;
        /* Unlink from established hashes. */
        spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
@@ -46,15 +63,11 @@ static void __inet_twsk_kill(struct inet_timewait_sock *tw,
        /* Disassociate with bind bucket. */
        bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num,
                        hashinfo->bhash_size)];
+
        spin_lock(&bhead->lock);
-       tb = tw->tw_tb;
-       if (tb) {
-               __hlist_del(&tw->tw_bind_node);
-               tw->tw_tb = NULL;
-               inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
-               refcnt++;
-       }
+       refcnt += inet_twsk_bind_unhash(tw, hashinfo);
        spin_unlock(&bhead->lock);
+
 #ifdef SOCK_REFCNT_DEBUG
        if (atomic_read(&tw->tw_refcnt) != 1) {
                printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n",