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netlink: add flow control for memory mapped I/O

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Add flow control for memory mapped RX. Since user-space usually doesn't
invoke recvmsg() when using memory mapped I/O, flow control is performed
in netlink_poll(). Dumps are allowed to continue if at least half of the
ring frames are unused.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2013-04-17 06:47:05 +00:00 committed by David S. Miller
parent f9c2288837
commit cd1df525da
1 changed files with 61 additions and 27 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

88
net/netlink/af_netlink.c
View file

@ -3,6 +3,7 @@
*
* Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
* Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@ -110,6 +111,29 @@ static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u
return &hash->table[jhash_1word(portid, hash->rnd) & hash->mask];
}
static void netlink_overrun(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
sk->sk_err = ENOBUFS;
sk->sk_error_report(sk);
}
}
atomic_inc(&sk->sk_drops);
}
static void netlink_rcv_wake(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (skb_queue_empty(&sk->sk_receive_queue))
clear_bit(NETLINK_CONGESTED, &nlk->state);
if (!test_bit(NETLINK_CONGESTED, &nlk->state))
wake_up_interruptible(&nlk->wait);
}
#ifdef CONFIG_NETLINK_MMAP
static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
{
@ -441,15 +465,48 @@ static void netlink_forward_ring(struct netlink_ring *ring)
} while (ring->head != head);
}
static bool netlink_dump_space(struct netlink_sock *nlk)
{
struct netlink_ring *ring = &nlk->rx_ring;
struct nl_mmap_hdr *hdr;
unsigned int n;
hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
if (hdr == NULL)
return false;
n = ring->head + ring->frame_max / 2;
if (n > ring->frame_max)
n -= ring->frame_max;
hdr = __netlink_lookup_frame(ring, n);
return hdr->nm_status == NL_MMAP_STATUS_UNUSED;
}
static unsigned int netlink_poll(struct file *file, struct socket *sock,
poll_table *wait)
{
struct sock *sk = sock->sk;
struct netlink_sock *nlk = nlk_sk(sk);
unsigned int mask;
int err;
if (nlk->cb != NULL && nlk->rx_ring.pg_vec != NULL)
netlink_dump(sk);
if (nlk->rx_ring.pg_vec != NULL) {
/* Memory mapped sockets don't call recvmsg(), so flow control
* for dumps is performed here. A dump is allowed to continue
* if at least half the ring is unused.
*/
while (nlk->cb != NULL && netlink_dump_space(nlk)) {
err = netlink_dump(sk);
if (err < 0) {
sk->sk_err = err;
sk->sk_error_report(sk);
break;
}
}
netlink_rcv_wake(sk);
}
mask = datagram_poll(file, sock, wait);
@ -623,8 +680,7 @@ static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
if (hdr == NULL) {
spin_unlock_bh(&sk->sk_receive_queue.lock);
kfree_skb(skb);
sk->sk_err = ENOBUFS;
sk->sk_error_report(sk);
netlink_overrun(sk);
return;
}
netlink_increment_head(ring);
@ -1329,19 +1385,6 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr,
return 0;
}
static void netlink_overrun(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
sk->sk_err = ENOBUFS;
sk->sk_error_report(sk);
}
}
atomic_inc(&sk->sk_drops);
}
static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
{
struct sock *sock;
@ -1484,16 +1527,6 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
return skb;
}
static void netlink_rcv_wake(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (skb_queue_empty(&sk->sk_receive_queue))
clear_bit(NETLINK_CONGESTED, &nlk->state);
if (!test_bit(NETLINK_CONGESTED, &nlk->state))
wake_up_interruptible(&nlk->wait);
}
static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
struct sock *ssk)
{
@ -1597,6 +1630,7 @@ struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size,
err2:
kfree_skb(skb);
spin_unlock_bh(&sk->sk_receive_queue.lock);
netlink_overrun(sk);
err1:
sock_put(sk);
return NULL;