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udpv6: Add lockless sendmsg() support 

This commit adds the same functionaliy to IPv6 that
commit 903ab86d19
Author: Herbert Xu <herbert@gondor.apana.org.au>
Date:   Tue Mar 1 02:36:48 2011 +0000

    udp: Add lockless transmit path

added to IPv4.

UDP transmit path can now run without a socket lock,
thus allowing multiple threads to send to a single socket
more efficiently.
This is only used when corking/MSG_MORE is not used.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Yasevich 2015-01-31 10:40:17 -05:00 committed by David S. Miller
parent d39d938c82
commit 03485f2adc
1 changed files with 20 additions and 4 deletions
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24
net/ipv6/udp.c
View File

@ -1177,6 +1177,7 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
if (len > INT_MAX - sizeof(struct udphdr))
return -EMSGSIZE;
getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag;
if (up->pending) {
/*
* There are pending frames.
@ -1307,6 +1308,20 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
goto do_confirm;
back_from_confirm:
/* Lockless fast path for the non-corking case */
if (!corkreq) {
struct sk_buff *skb;
skb = ip6_make_skb(sk, getfrag, msg, ulen,
sizeof(struct udphdr), hlimit, tclass, opt,
&fl6, (struct rt6_info *)dst,
msg->msg_flags, dontfrag);
err = PTR_ERR(skb);
if (!IS_ERR_OR_NULL(skb))
err = udp_v6_send_skb(skb, &fl6);
goto release_dst;
}
lock_sock(sk);
if (unlikely(up->pending)) {
/* The socket is already corked while preparing it. */
@ -1324,7 +1339,6 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
if (dontfrag < 0)
dontfrag = np->dontfrag;
up->len += ulen;
getfrag = is_udplite ? udplite_getfrag : ip_generic_getfrag;
err = ip6_append_data(sk, getfrag, msg, ulen,
sizeof(struct udphdr), hlimit, tclass, opt, &fl6,
(struct rt6_info *)dst,
@ -1336,6 +1350,11 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
up->pending = 0;
if (err > 0)
err = np->recverr ? net_xmit_errno(err) : 0;
release_sock(sk);
release_dst:
if (dst) {
if (connected) {
ip6_dst_store(sk, dst,
@ -1352,9 +1371,6 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
dst = NULL;
}
if (err > 0)
err = np->recverr ? net_xmit_errno(err) : 0;
release_sock(sk);
out:
dst_release(dst);
fl6_sock_release(flowlabel);