From 43815482370c510c569fd18edb57afcb0fa8cab6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 29 Apr 2010 11:01:49 +0000 Subject: net: sock_def_readable() and friends RCU conversion sk_callback_lock rwlock actually protects sk->sk_sleep pointer, so we need two atomic operations (and associated dirtying) per incoming packet. RCU conversion is pretty much needed : 1) Add a new structure, called "struct socket_wq" to hold all fields that will need rcu_read_lock() protection (currently: a wait_queue_head_t and a struct fasync_struct pointer). [Future patch will add a list anchor for wakeup coalescing] 2) Attach one of such structure to each "struct socket" created in sock_alloc_inode(). 3) Respect RCU grace period when freeing a "struct socket_wq" 4) Change sk_sleep pointer in "struct sock" by sk_wq, pointer to "struct socket_wq" 5) Change sk_sleep() function to use new sk->sk_wq instead of sk->sk_sleep 6) Change sk_has_sleeper() to wq_has_sleeper() that must be used inside a rcu_read_lock() section. 7) Change all sk_has_sleeper() callers to : - Use rcu_read_lock() instead of read_lock(&sk->sk_callback_lock) - Use wq_has_sleeper() to eventually wakeup tasks. - Use rcu_read_unlock() instead of read_unlock(&sk->sk_callback_lock) 8) sock_wake_async() is modified to use rcu protection as well. 9) Exceptions : macvtap, drivers/net/tun.c, af_unix use integrated "struct socket_wq" instead of dynamically allocated ones. They dont need rcu freeing. Some cleanups or followups are probably needed, (possible sk_callback_lock conversion to a spinlock for example...). Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/tun.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'drivers/net/tun.c') diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 20a17938c62b..e525a6cf5587 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -109,7 +109,7 @@ struct tun_struct { struct tap_filter txflt; struct socket socket; - + struct socket_wq wq; #ifdef TUN_DEBUG int debug; #endif @@ -323,7 +323,7 @@ static void tun_net_uninit(struct net_device *dev) /* Inform the methods they need to stop using the dev. */ if (tfile) { - wake_up_all(&tun->socket.wait); + wake_up_all(&tun->wq.wait); if (atomic_dec_and_test(&tfile->count)) __tun_detach(tun); } @@ -398,7 +398,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) /* Notify and wake up reader process */ if (tun->flags & TUN_FASYNC) kill_fasync(&tun->fasync, SIGIO, POLL_IN); - wake_up_interruptible_poll(&tun->socket.wait, POLLIN | + wake_up_interruptible_poll(&tun->wq.wait, POLLIN | POLLRDNORM | POLLRDBAND); return NETDEV_TX_OK; @@ -498,7 +498,7 @@ static unsigned int tun_chr_poll(struct file *file, poll_table * wait) DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name); - poll_wait(file, &tun->socket.wait, wait); + poll_wait(file, &tun->wq.wait, wait); if (!skb_queue_empty(&sk->sk_receive_queue)) mask |= POLLIN | POLLRDNORM; @@ -773,7 +773,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, DBG(KERN_INFO "%s: tun_chr_read\n", tun->dev->name); - add_wait_queue(&tun->socket.wait, &wait); + add_wait_queue(&tun->wq.wait, &wait); while (len) { current->state = TASK_INTERRUPTIBLE; @@ -804,7 +804,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, } current->state = TASK_RUNNING; - remove_wait_queue(&tun->socket.wait, &wait); + remove_wait_queue(&tun->wq.wait, &wait); return ret; } @@ -861,6 +861,7 @@ static struct rtnl_link_ops tun_link_ops __read_mostly = { static void tun_sock_write_space(struct sock *sk) { struct tun_struct *tun; + wait_queue_head_t *wqueue; if (!sock_writeable(sk)) return; @@ -868,8 +869,9 @@ static void tun_sock_write_space(struct sock *sk) if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags)) return; - if (sk_sleep(sk) && waitqueue_active(sk_sleep(sk))) - wake_up_interruptible_sync_poll(sk_sleep(sk), POLLOUT | + wqueue = sk_sleep(sk); + if (wqueue && waitqueue_active(wqueue)) + wake_up_interruptible_sync_poll(wqueue, POLLOUT | POLLWRNORM | POLLWRBAND); tun = tun_sk(sk)->tun; @@ -1039,7 +1041,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) if (!sk) goto err_free_dev; - init_waitqueue_head(&tun->socket.wait); + tun->socket.wq = &tun->wq; + init_waitqueue_head(&tun->wq.wait); tun->socket.ops = &tun_socket_ops; sock_init_data(&tun->socket, sk); sk->sk_write_space = tun_sock_write_space; -- cgit v1.2.2