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path: root/drivers/net/pppoe.c
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Diffstat (limited to 'drivers/net/pppoe.c')
-rw-r--r--drivers/net/pppoe.c87
1 files changed, 50 insertions, 37 deletions
diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
index bc4fc30bc85e..6f98834e6ace 100644
--- a/drivers/net/pppoe.c
+++ b/drivers/net/pppoe.c
@@ -241,54 +241,53 @@ static inline struct pppox_sock *delete_item(unsigned long sid, char *addr, int
static void pppoe_flush_dev(struct net_device *dev)
{
int hash;
-
BUG_ON(dev == NULL);
- read_lock_bh(&pppoe_hash_lock);
+ write_lock_bh(&pppoe_hash_lock);
for (hash = 0; hash < PPPOE_HASH_SIZE; hash++) {
struct pppox_sock *po = item_hash_table[hash];
while (po != NULL) {
- if (po->pppoe_dev == dev) {
- struct sock *sk = sk_pppox(po);
-
- sock_hold(sk);
- po->pppoe_dev = NULL;
+ struct sock *sk = sk_pppox(po);
+ if (po->pppoe_dev != dev) {
+ po = po->next;
+ continue;
+ }
+ po->pppoe_dev = NULL;
+ dev_put(dev);
- /* We hold a reference to SK, now drop the
- * hash table lock so that we may attempt
- * to lock the socket (which can sleep).
- */
- read_unlock_bh(&pppoe_hash_lock);
- lock_sock(sk);
+ /* We always grab the socket lock, followed by the
+ * pppoe_hash_lock, in that order. Since we should
+ * hold the sock lock while doing any unbinding,
+ * we need to release the lock we're holding.
+ * Hold a reference to the sock so it doesn't disappear
+ * as we're jumping between locks.
+ */
- if (sk->sk_state &
- (PPPOX_CONNECTED | PPPOX_BOUND)) {
- pppox_unbind_sock(sk);
- dev_put(dev);
- sk->sk_state = PPPOX_ZOMBIE;
- sk->sk_state_change(sk);
- }
+ sock_hold(sk);
- release_sock(sk);
+ write_unlock_bh(&pppoe_hash_lock);
+ lock_sock(sk);
- sock_put(sk);
+ if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND)) {
+ pppox_unbind_sock(sk);
+ sk->sk_state = PPPOX_ZOMBIE;
+ sk->sk_state_change(sk);
+ }
- read_lock_bh(&pppoe_hash_lock);
+ release_sock(sk);
+ sock_put(sk);
- /* Now restart from the beginning of this
- * hash chain. We always NULL out pppoe_dev
- * so we are guaranteed to make forward
- * progress.
- */
- po = item_hash_table[hash];
- continue;
- }
- po = po->next;
+ /* Restart scan at the beginning of this hash chain.
+ * While the lock was dropped the chain contents may
+ * have changed.
+ */
+ write_lock_bh(&pppoe_hash_lock);
+ po = item_hash_table[hash];
}
}
- read_unlock_bh(&pppoe_hash_lock);
+ write_unlock_bh(&pppoe_hash_lock);
}
static int pppoe_device_event(struct notifier_block *this,
@@ -504,28 +503,42 @@ static int pppoe_release(struct socket *sock)
if (!sk)
return 0;
- if (sock_flag(sk, SOCK_DEAD))
+ lock_sock(sk);
+ if (sock_flag(sk, SOCK_DEAD)){
+ release_sock(sk);
return -EBADF;
+ }
pppox_unbind_sock(sk);
/* Signal the death of the socket. */
sk->sk_state = PPPOX_DEAD;
+
+ /* Write lock on hash lock protects the entire "po" struct from
+ * concurrent updates via pppoe_flush_dev. The "po" struct should
+ * be considered part of the hash table contents, thus protected
+ * by the hash table lock */
+ write_lock_bh(&pppoe_hash_lock);
+
po = pppox_sk(sk);
if (po->pppoe_pa.sid) {
- delete_item(po->pppoe_pa.sid, po->pppoe_pa.remote, po->pppoe_ifindex);
+ __delete_item(po->pppoe_pa.sid,
+ po->pppoe_pa.remote, po->pppoe_ifindex);
}
- if (po->pppoe_dev)
+ if (po->pppoe_dev) {
dev_put(po->pppoe_dev);
+ po->pppoe_dev = NULL;
+ }
- po->pppoe_dev = NULL;
+ write_unlock_bh(&pppoe_hash_lock);
sock_orphan(sk);
sock->sk = NULL;
skb_queue_purge(&sk->sk_receive_queue);
+ release_sock(sk);
sock_put(sk);
return 0;