skbuff: Function to send an skbuf on a socket

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>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4093552be1dee0a441d033ffb373ea4dfcc6e243..18e76bf9574e3ab6afc1e5f8ece8dc256430cd46 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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,

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c27da51d14e4903937b34efe839999cfca2e049e..9c0e015ff3fe2753f8ca20f6533b7aa6b93caca3 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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