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skbuff: Function to send an skbuf on a socket

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Add skb_send_sock to send an skbuff on a socket within the kernel.
Arguments include an offset so that an skbuf might be sent in mulitple
calls (e.g. send buffer limit is hit).

Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Herbert 2017-07-28 16:22:42 -07:00 committed by David S. Miller
parent 306b13eb3c
commit 20bf50de30
2 changed files with 104 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
include/linux/skbuff.h
View file

@ -3113,6 +3113,9 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
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);
int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
int len);
int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len);
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,

101
net/core/skbuff.c
View file

@ -1982,6 +1982,107 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
}
EXPORT_SYMBOL_GPL(skb_splice_bits);
/* Send skb data on a socket. Socket must be locked. */
int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
int len)
{
unsigned int orig_len = len;
struct sk_buff *head = skb;
unsigned short fragidx;
int slen, ret;
do_frag_list:
/* Deal with head data */
while (offset < skb_headlen(skb) && len) {
struct kvec kv;
struct msghdr msg;
slen = min_t(int, len, skb_headlen(skb) - offset);
kv.iov_base = skb->data + offset;
kv.iov_len = len;
memset(&msg, 0, sizeof(msg));
ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);
if (ret <= 0)
goto error;
offset += ret;
len -= ret;
}
/* All the data was skb head? */
if (!len)
goto out;
/* Make offset relative to start of frags */
offset -= skb_headlen(skb);
/* Find where we are in frag list */
for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
if (offset < frag->size)
break;
offset -= frag->size;
}
for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
skb_frag_t *frag = &skb_shinfo(skb)->frags[fragidx];
slen = min_t(size_t, len, frag->size - offset);
while (slen) {
ret = kernel_sendpage_locked(sk, frag->page.p,
frag->page_offset + offset,
slen, MSG_DONTWAIT);
if (ret <= 0)
goto error;
len -= ret;
offset += ret;
slen -= ret;
}
offset = 0;
}
if (len) {
/* Process any frag lists */
if (skb == head) {
if (skb_has_frag_list(skb)) {
skb = skb_shinfo(skb)->frag_list;
goto do_frag_list;
}
} else if (skb->next) {
skb = skb->next;
goto do_frag_list;
}
}
out:
return orig_len - len;
error:
return orig_len == len ? ret : orig_len - len;
}
EXPORT_SYMBOL_GPL(skb_send_sock_locked);
/* Send skb data on a socket. */
int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
{
int ret = 0;
lock_sock(sk);
ret = skb_send_sock_locked(sk, skb, offset, len);
release_sock(sk);
return ret;
}
EXPORT_SYMBOL_GPL(skb_send_sock);
/**
* skb_store_bits - store bits from kernel buffer to skb
* @skb: destination buffer