netlink: add flow control for memory mapped I/O
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>
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cd1df525da
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@ -3,6 +3,7 @@
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*
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* Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>
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* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
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* Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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@ -110,6 +111,29 @@ static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u
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return &hash->table[jhash_1word(portid, hash->rnd) & hash->mask];
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}
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static void netlink_overrun(struct sock *sk)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
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if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
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sk->sk_err = ENOBUFS;
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sk->sk_error_report(sk);
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}
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}
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atomic_inc(&sk->sk_drops);
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}
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static void netlink_rcv_wake(struct sock *sk)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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if (skb_queue_empty(&sk->sk_receive_queue))
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clear_bit(NETLINK_CONGESTED, &nlk->state);
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if (!test_bit(NETLINK_CONGESTED, &nlk->state))
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wake_up_interruptible(&nlk->wait);
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}
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#ifdef CONFIG_NETLINK_MMAP
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static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
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{
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@ -441,15 +465,48 @@ static void netlink_forward_ring(struct netlink_ring *ring)
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} while (ring->head != head);
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}
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static bool netlink_dump_space(struct netlink_sock *nlk)
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{
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struct netlink_ring *ring = &nlk->rx_ring;
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struct nl_mmap_hdr *hdr;
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unsigned int n;
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hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
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if (hdr == NULL)
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return false;
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n = ring->head + ring->frame_max / 2;
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if (n > ring->frame_max)
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n -= ring->frame_max;
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hdr = __netlink_lookup_frame(ring, n);
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return hdr->nm_status == NL_MMAP_STATUS_UNUSED;
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}
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static unsigned int netlink_poll(struct file *file, struct socket *sock,
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poll_table *wait)
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{
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struct sock *sk = sock->sk;
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struct netlink_sock *nlk = nlk_sk(sk);
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unsigned int mask;
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int err;
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if (nlk->cb != NULL && nlk->rx_ring.pg_vec != NULL)
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netlink_dump(sk);
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if (nlk->rx_ring.pg_vec != NULL) {
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/* Memory mapped sockets don't call recvmsg(), so flow control
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* for dumps is performed here. A dump is allowed to continue
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* if at least half the ring is unused.
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*/
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while (nlk->cb != NULL && netlink_dump_space(nlk)) {
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err = netlink_dump(sk);
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if (err < 0) {
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sk->sk_err = err;
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sk->sk_error_report(sk);
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break;
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}
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}
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netlink_rcv_wake(sk);
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}
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mask = datagram_poll(file, sock, wait);
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@ -623,8 +680,7 @@ static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
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if (hdr == NULL) {
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spin_unlock_bh(&sk->sk_receive_queue.lock);
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kfree_skb(skb);
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sk->sk_err = ENOBUFS;
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sk->sk_error_report(sk);
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netlink_overrun(sk);
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return;
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}
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netlink_increment_head(ring);
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@ -1329,19 +1385,6 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr,
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return 0;
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}
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static void netlink_overrun(struct sock *sk)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
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if (!test_and_set_bit(NETLINK_CONGESTED, &nlk_sk(sk)->state)) {
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sk->sk_err = ENOBUFS;
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sk->sk_error_report(sk);
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}
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}
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atomic_inc(&sk->sk_drops);
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}
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static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
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{
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struct sock *sock;
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@ -1484,16 +1527,6 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
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return skb;
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}
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static void netlink_rcv_wake(struct sock *sk)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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if (skb_queue_empty(&sk->sk_receive_queue))
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clear_bit(NETLINK_CONGESTED, &nlk->state);
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if (!test_bit(NETLINK_CONGESTED, &nlk->state))
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wake_up_interruptible(&nlk->wait);
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}
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static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
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struct sock *ssk)
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{
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@ -1597,6 +1630,7 @@ struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size,
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err2:
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kfree_skb(skb);
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spin_unlock_bh(&sk->sk_receive_queue.lock);
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netlink_overrun(sk);
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err1:
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sock_put(sk);
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return NULL;
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