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authorEric Dumazet <eric.dumazet@gmail.com>2010-04-29 11:01:49 +0000
committerDavid S. Miller <davem@davemloft.net>2010-05-01 15:00:15 -0700
commit43815482370c510c569fd18edb57afcb0fa8cab6 (patch)
tree063efaae3758402b84f056438b704d1de68f7837 /drivers/net/tun.c
parent83d7eb2979cd3390c375470225dd2d8f2009bc70 (diff)
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 <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tun.c')
-rw-r--r--drivers/net/tun.c21
1 files changed, 12 insertions, 9 deletions
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;