diff --git a/net/core/sock.c b/net/core/sock.c index ab865b04130b..be20a1af20e5 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -146,6 +146,7 @@ static DEFINE_MUTEX(proto_list_mutex); static LIST_HEAD(proto_list); +static void sock_def_write_space_wfree(struct sock *sk); static void sock_def_write_space(struct sock *sk); /** @@ -2333,7 +2334,7 @@ void sock_wfree(struct sk_buff *skb) sk->sk_write_space == sock_def_write_space) { rcu_read_lock(); free = refcount_sub_and_test(len, &sk->sk_wmem_alloc); - sock_def_write_space(sk); + sock_def_write_space_wfree(sk); rcu_read_unlock(); if (unlikely(free)) __sk_free(sk); @@ -3218,6 +3219,29 @@ static void sock_def_write_space(struct sock *sk) rcu_read_unlock(); } +/* An optimised version of sock_def_write_space(), should only be called + * for SOCK_RCU_FREE sockets under RCU read section and after putting + * ->sk_wmem_alloc. + */ +static void sock_def_write_space_wfree(struct sock *sk) +{ + /* Do not wake up a writer until he can make "significant" + * progress. --DaveM + */ + if (sock_writeable(sk)) { + struct socket_wq *wq = rcu_dereference(sk->sk_wq); + + /* rely on refcount_sub from sock_wfree() */ + smp_mb__after_atomic(); + if (wq && waitqueue_active(&wq->wait)) + wake_up_interruptible_sync_poll(&wq->wait, EPOLLOUT | + EPOLLWRNORM | EPOLLWRBAND); + + /* Should agree with poll, otherwise some programs break */ + sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); + } +} + static void sock_def_destruct(struct sock *sk) { }