From 869e7c62486ec0e170a9771acaa251d1a33b5871 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Thu, 21 May 2015 16:59:59 +0200 Subject: [PATCH] net: af_unix: implement stream sendpage support This patch implements sendpage support for AF_UNIX SOCK_STREAM sockets. This is also required for a complete splice implementation. The implementation is a bit tricky because we append to already existing skbs and so have to hold unix_sk->readlock to protect the reading side from either advancing UNIXCB.consumed or freeing the skb at the socket receive tail. Signed-off-by: Hannes Frederic Sowa Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/unix/af_unix.c | 99 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 98 insertions(+), 1 deletion(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 941b3d26e3bf..7762c0b46721 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -518,6 +518,8 @@ static int unix_ioctl(struct socket *, unsigned int, unsigned long); static int unix_shutdown(struct socket *, int); static int unix_stream_sendmsg(struct socket *, struct msghdr *, size_t); static int unix_stream_recvmsg(struct socket *, struct msghdr *, size_t, int); +static ssize_t unix_stream_sendpage(struct socket *, struct page *, int offset, + size_t size, int flags); static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t); static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int); static int unix_dgram_connect(struct socket *, struct sockaddr *, @@ -558,7 +560,7 @@ static const struct proto_ops unix_stream_ops = { .sendmsg = unix_stream_sendmsg, .recvmsg = unix_stream_recvmsg, .mmap = sock_no_mmap, - .sendpage = sock_no_sendpage, + .sendpage = unix_stream_sendpage, .set_peek_off = unix_set_peek_off, }; @@ -1720,6 +1722,101 @@ out_err: return sent ? : err; } +static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page, + int offset, size_t size, int flags) +{ + int err = 0; + bool send_sigpipe = true; + struct sock *other, *sk = socket->sk; + struct sk_buff *skb, *newskb = NULL, *tail = NULL; + + if (flags & MSG_OOB) + return -EOPNOTSUPP; + + other = unix_peer(sk); + if (!other || sk->sk_state != TCP_ESTABLISHED) + return -ENOTCONN; + + if (false) { +alloc_skb: + unix_state_unlock(other); + mutex_unlock(&unix_sk(other)->readlock); + newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT, + &err, 0); + if (!newskb) + return err; + } + + /* we must acquire readlock as we modify already present + * skbs in the sk_receive_queue and mess with skb->len + */ + err = mutex_lock_interruptible(&unix_sk(other)->readlock); + if (err) { + err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS; + send_sigpipe = false; + goto err; + } + + if (sk->sk_shutdown & SEND_SHUTDOWN) { + err = -EPIPE; + goto err_unlock; + } + + unix_state_lock(other); + + if (sock_flag(other, SOCK_DEAD) || + other->sk_shutdown & RCV_SHUTDOWN) { + err = -EPIPE; + goto err_state_unlock; + } + + skb = skb_peek_tail(&other->sk_receive_queue); + if (tail && tail == skb) { + skb = newskb; + } else if (!skb) { + if (newskb) + skb = newskb; + else + goto alloc_skb; + } else if (newskb) { + /* this is fast path, we don't necessarily need to + * call to kfree_skb even though with newskb == NULL + * this - does no harm + */ + consume_skb(newskb); + } + + if (skb_append_pagefrags(skb, page, offset, size)) { + tail = skb; + goto alloc_skb; + } + + skb->len += size; + skb->data_len += size; + skb->truesize += size; + atomic_add(size, &sk->sk_wmem_alloc); + + if (newskb) + __skb_queue_tail(&other->sk_receive_queue, newskb); + + unix_state_unlock(other); + mutex_unlock(&unix_sk(other)->readlock); + + other->sk_data_ready(other); + + return size; + +err_state_unlock: + unix_state_unlock(other); +err_unlock: + mutex_unlock(&unix_sk(other)->readlock); +err: + kfree_skb(newskb); + if (send_sigpipe && !(flags & MSG_NOSIGNAL)) + send_sig(SIGPIPE, current, 0); + return err; +} + static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) { -- 2.20.1