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Date: Fri, 24 Sep 2010 18:25:16 +0100
From: Alban Crequy <alban.crequy@...labora.co.uk>
To: Alban Crequy <alban.crequy@...labora.co.uk>
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <eric.dumazet@...il.com>,
Stephen Hemminger <shemminger@...tta.com>,
Cyrill Gorcunov <gorcunov@...nvz.org>,
Alexey Dobriyan <adobriyan@...il.com>,
Lennart Poettering <lennart@...ttering.net>,
Kay Sievers <kay.sievers@...y.org>,
Ian Molton <ian.molton@...labora.co.uk>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
dbus@...edesktop.org, Alban Crequy <alban.crequy@...labora.co.uk>
Subject: [PATCH 5/5] AF_UNIX: deliver the data to all the multicast peers
With multicast sockets, unix_stream_sendmsg() needs to deliver the data to
zero, one or several recipients. skb_clone() is used to get as many sk_buff as
recipients.
If a multicast peer is too slow to receive the packets, it will block the
sender at some point in sock_alloc_send_skb().
A sender can receive SIGPIPE caused by an unique peer on the multicast group.
This is probably not what we want.
I tested this with a few peers and either sending data, receiving data or just
sleeping.
Signed-off-by: Alban Crequy <alban.crequy@...labora.co.uk>
---
net/unix/af_unix.c | 77 +++++++++++++++++++++++++++++++++++----------------
1 files changed, 53 insertions(+), 24 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index f259849..01cb603 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1640,10 +1640,10 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
struct sock *sk = sock->sk;
struct sock *other = NULL;
struct sock **others = NULL;
+ struct sock **others_cur = NULL;
int max_others;
struct sockaddr_un *sunaddr = msg->msg_name;
int err, size;
- struct sk_buff *skb;
int sent = 0;
struct scm_cookie tmp_scm;
bool fds_sent = false;
@@ -1668,15 +1668,22 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
other = unix_peer(sk);
if (!other)
goto out_err;
+ err = -ENOMEM;
+ others = kzalloc(2 * sizeof(void *), GFP_KERNEL);
+ if (!others)
+ goto out_err;
+ others[0] = other;
} else {
sunaddr = NULL;
- err = -ENOTCONN;
max_others = atomic_read(&unix_nr_multicast_socks);
+ err = -ENOMEM;
others = kzalloc((max_others + 1) * sizeof(void *), GFP_KERNEL);
+ if (!others)
+ goto out_err;
unix_find_other(sock_net(sk), u->addr->name,
u->addr->len, 0, u->addr->hash, 1, others, max_others, &err);
+ err = -ENOTCONN;
other = others[0];
- kfree(others);
if (!other)
goto out_err;
}
@@ -1685,6 +1692,8 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
goto pipe_err;
while (sent < len) {
+ struct sk_buff *skb;
+ struct sk_buff *skb_cloned;
/*
* Optimisation for the fact that under 0.01% of X
* messages typically need breaking up.
@@ -1718,43 +1727,61 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
*/
size = min_t(int, size, skb_tailroom(skb));
- memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
- /* Only send the fds in the first buffer */
- if (siocb->scm->fp && !fds_sent) {
- err = unix_attach_fds(siocb->scm, skb);
- if (err) {
- kfree_skb(skb);
- goto out_err;
- }
- fds_sent = true;
- }
-
err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
if (err) {
kfree_skb(skb);
goto out_err;
}
- unix_state_lock(other);
+ others_cur = others;
+ while (*others_cur != NULL) {
+ skb_cloned = skb_clone(skb, GFP_KERNEL);
+ if (!skb_cloned) {
+ kfree_skb(skb);
+ goto out_err;
+ }
+ skb_set_owner_w(skb_cloned, sk);
+
+ memcpy(UNIXCREDS(skb_cloned), &siocb->scm->creds, sizeof(struct ucred));
+ /* Only send the fds in the first buffer of each
+ * recipient */
+ if (siocb->scm->fp && !fds_sent) {
+ err = unix_attach_fds(siocb->scm, skb_cloned);
+ if (err) {
+ kfree_skb(skb);
+ kfree_skb(skb_cloned);
+ goto out_err;
+ }
+ }
+
+ unix_state_lock(*others_cur);
- if (sock_flag(other, SOCK_DEAD) ||
- (other->sk_shutdown & RCV_SHUTDOWN))
- goto pipe_err_free;
+ if (sock_flag(*others_cur, SOCK_DEAD) ||
+ ((*others_cur)->sk_shutdown & RCV_SHUTDOWN)) {
+ unix_state_unlock(*others_cur);
+ kfree_skb(skb);
+ kfree_skb(skb_cloned);
+ goto pipe_err;
+ }
- skb_queue_tail(&other->sk_receive_queue, skb);
- unix_state_unlock(other);
- other->sk_data_ready(other, size);
+ skb_queue_tail(&(*others_cur)->sk_receive_queue,
+ skb_cloned);
+ unix_state_unlock(*others_cur);
+ (*others_cur)->sk_data_ready(*others_cur, size);
+ others_cur++;
+ }
+ kfree_skb(skb);
+ fds_sent = true;
sent += size;
}
scm_destroy(siocb->scm);
siocb->scm = NULL;
+ if (others)
+ kfree(others);
return sent;
-pipe_err_free:
- unix_state_unlock(other);
- kfree_skb(skb);
pipe_err:
if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
send_sig(SIGPIPE, current, 0);
@@ -1762,6 +1789,8 @@ pipe_err:
out_err:
scm_destroy(siocb->scm);
siocb->scm = NULL;
+ if (others)
+ kfree(others);
return sent ? : err;
}
--
1.7.1
--
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