diff options
Diffstat (limited to 'net/netlink/af_netlink.c')
| -rw-r--r-- | net/netlink/af_netlink.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 7a186e74b1b3..f1de72de273e 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -96,6 +96,14 @@ static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait); static int netlink_dump(struct sock *sk); static void netlink_skb_destructor(struct sk_buff *skb); +/* nl_table locking explained: + * Lookup and traversal are protected with nl_sk_hash_lock or nl_table_lock + * combined with an RCU read-side lock. Insertion and removal are protected + * with nl_sk_hash_lock while using RCU list modification primitives and may + * run in parallel to nl_table_lock protected lookups. Destruction of the + * Netlink socket may only occur *after* nl_table_lock has been acquired + * either during or after the socket has been removed from the list. + */ DEFINE_RWLOCK(nl_table_lock); EXPORT_SYMBOL_GPL(nl_table_lock); static atomic_t nl_table_users = ATOMIC_INIT(0); @@ -109,10 +117,10 @@ EXPORT_SYMBOL_GPL(nl_sk_hash_lock); static int lockdep_nl_sk_hash_is_held(void) { #ifdef CONFIG_LOCKDEP - return (debug_locks) ? lockdep_is_held(&nl_sk_hash_lock) : 1; -#else - return 1; + if (debug_locks) + return lockdep_is_held(&nl_sk_hash_lock) || lockdep_is_held(&nl_table_lock); #endif + return 1; } static ATOMIC_NOTIFIER_HEAD(netlink_chain); @@ -1028,11 +1036,13 @@ static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid) struct netlink_table *table = &nl_table[protocol]; struct sock *sk; + read_lock(&nl_table_lock); rcu_read_lock(); sk = __netlink_lookup(table, portid, net); if (sk) sock_hold(sk); rcu_read_unlock(); + read_unlock(&nl_table_lock); return sk; } @@ -1257,9 +1267,6 @@ static int netlink_release(struct socket *sock) } netlink_table_ungrab(); - /* Wait for readers to complete */ - synchronize_net(); - kfree(nlk->groups); nlk->groups = NULL; @@ -1281,6 +1288,7 @@ static int netlink_autobind(struct socket *sock) retry: cond_resched(); + netlink_table_grab(); rcu_read_lock(); if (__netlink_lookup(table, portid, net)) { /* Bind collision, search negative portid values. */ @@ -1288,9 +1296,11 @@ retry: if (rover > -4097) rover = -4097; rcu_read_unlock(); + netlink_table_ungrab(); goto retry; } rcu_read_unlock(); + netlink_table_ungrab(); err = netlink_insert(sk, net, portid); if (err == -EADDRINUSE) @@ -2921,14 +2931,16 @@ static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos) } static void *netlink_seq_start(struct seq_file *seq, loff_t *pos) - __acquires(RCU) + __acquires(nl_table_lock) __acquires(RCU) { + read_lock(&nl_table_lock); rcu_read_lock(); return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN; } static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) { + struct rhashtable *ht; struct netlink_sock *nlk; struct nl_seq_iter *iter; struct net *net; @@ -2943,19 +2955,19 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) iter = seq->private; nlk = v; - rht_for_each_entry_rcu(nlk, nlk->node.next, node) + i = iter->link; + ht = &nl_table[i].hash; + rht_for_each_entry(nlk, nlk->node.next, ht, node) if (net_eq(sock_net((struct sock *)nlk), net)) return nlk; - i = iter->link; j = iter->hash_idx + 1; do { - struct rhashtable *ht = &nl_table[i].hash; const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht); for (; j < tbl->size; j++) { - rht_for_each_entry_rcu(nlk, tbl->buckets[j], node) { + rht_for_each_entry(nlk, tbl->buckets[j], ht, node) { if (net_eq(sock_net((struct sock *)nlk), net)) { iter->link = i; iter->hash_idx = j; @@ -2971,9 +2983,10 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos) } static void netlink_seq_stop(struct seq_file *seq, void *v) - __releases(RCU) + __releases(RCU) __releases(nl_table_lock) { rcu_read_unlock(); + read_unlock(&nl_table_lock); } |