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net: make skb_splice_bits more configureable

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Prepare skb_splice_bits to be able to deal with AF_UNIX sockets.

AF_UNIX sockets don't use lock_sock/release_sock and thus we have to
use a callback to make the locking and unlocking configureable.

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hannes Frederic Sowa 2015-05-21 17:00:00 +02:00 committed by David S. Miller
parent 869e7c6248
commit a60e3cc7c9
3 changed files with 40 additions and 21 deletions
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11
include/linux/skbuff.h
View file

@ -35,6 +35,7 @@
#include <linux/netdev_features.h>
#include <linux/sched.h>
#include <net/flow_dissector.h>
#include <linux/splice.h>
/* A. Checksumming of received packets by device.
*
@ -2699,9 +2700,15 @@ int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
int len, __wsum csum);
int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
ssize_t skb_socket_splice(struct sock *sk,
struct pipe_inode_info *pipe,
struct splice_pipe_desc *spd);
int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
struct pipe_inode_info *pipe, unsigned int len,
unsigned int flags);
unsigned int flags,
ssize_t (*splice_cb)(struct sock *,
struct pipe_inode_info *,
struct splice_pipe_desc *));
void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,

45
net/core/skbuff.c
View file

@ -1870,15 +1870,39 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
return false;
}
ssize_t skb_socket_splice(struct sock *sk,
struct pipe_inode_info *pipe,
struct splice_pipe_desc *spd)
{
int ret;
/* Drop the socket lock, otherwise we have reverse
* locking dependencies between sk_lock and i_mutex
* here as compared to sendfile(). We enter here
* with the socket lock held, and splice_to_pipe() will
* grab the pipe inode lock. For sendfile() emulation,
* we call into ->sendpage() with the i_mutex lock held
* and networking will grab the socket lock.
*/
release_sock(sk);
ret = splice_to_pipe(pipe, spd);
lock_sock(sk);
return ret;
}
/*
* Map data from the skb to a pipe. Should handle both the linear part,
* the fragments, and the frag list. It does NOT handle frag lists within
* the frag list, if such a thing exists. We'd probably need to recurse to
* handle that cleanly.
*/
int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
struct pipe_inode_info *pipe, unsigned int tlen,
unsigned int flags)
unsigned int flags,
ssize_t (*splice_cb)(struct sock *,
struct pipe_inode_info *,
struct splice_pipe_desc *))
{
struct partial_page partial[MAX_SKB_FRAGS];
struct page *pages[MAX_SKB_FRAGS];
@ -1891,7 +1915,6 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
.spd_release = sock_spd_release,
};
struct sk_buff *frag_iter;
struct sock *sk = skb->sk;
int ret = 0;
/*
@ -1914,20 +1937,8 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset,
}
done:
if (spd.nr_pages) {
/*
* Drop the socket lock, otherwise we have reverse
* locking dependencies between sk_lock and i_mutex
* here as compared to sendfile(). We enter here
* with the socket lock held, and splice_to_pipe() will
* grab the pipe inode lock. For sendfile() emulation,
* we call into ->sendpage() with the i_mutex lock held
* and networking will grab the socket lock.
*/
release_sock(sk);
ret = splice_to_pipe(pipe, &spd);
lock_sock(sk);
}
if (spd.nr_pages)
ret = splice_cb(sk, pipe, &spd);
return ret;
}

5
net/ipv4/tcp.c
View file

@ -695,8 +695,9 @@ static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
struct tcp_splice_state *tss = rd_desc->arg.data;
int ret;
ret = skb_splice_bits(skb, offset, tss->pipe, min(rd_desc->count, len),
tss->flags);
ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
min(rd_desc->count, len), tss->flags,
skb_socket_splice);
if (ret > 0)
rd_desc->count -= ret;
return ret;