ip: convert tcp_sendmsg() to iov_iter primitives
patch is actually smaller than it seems to be - most of it is unindenting
the inner loop body in tcp_sendmsg() itself...
the bit in tcp_input.c is going to get reverted very soon - that's what
memcpy_from_msg() will become, but not in this commit; let's keep it
reasonably contained...
There's one potentially subtle change here: in case of short copy from
userland, mainline tcp_send_syn_data() discards the skb it has allocated
and falls back to normal path, where we'll send as much as possible after
rereading the same data again. This patch trims SYN+data skb instead -
that way we don't need to copy from the same place twice.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3075723..9d72a0f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1067,11 +1067,10 @@
int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t size)
{
- const struct iovec *iov;
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
- int iovlen, flags, err, copied = 0;
- int mss_now = 0, size_goal, copied_syn = 0, offset = 0;
+ int flags, err, copied = 0;
+ int mss_now = 0, size_goal, copied_syn = 0;
bool sg;
long timeo;
@@ -1084,7 +1083,6 @@
goto out;
else if (err)
goto out_err;
- offset = copied_syn;
}
timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
@@ -1118,8 +1116,6 @@
mss_now = tcp_send_mss(sk, &size_goal, flags);
/* Ok commence sending. */
- iovlen = msg->msg_iter.nr_segs;
- iov = msg->msg_iter.iov;
copied = 0;
err = -EPIPE;
@@ -1128,151 +1124,134 @@
sg = !!(sk->sk_route_caps & NETIF_F_SG);
- while (--iovlen >= 0) {
- size_t seglen = iov->iov_len;
- unsigned char __user *from = iov->iov_base;
+ while (iov_iter_count(&msg->msg_iter)) {
+ int copy = 0;
+ int max = size_goal;
- iov++;
- if (unlikely(offset > 0)) { /* Skip bytes copied in SYN */
- if (offset >= seglen) {
- offset -= seglen;
- continue;
- }
- seglen -= offset;
- from += offset;
- offset = 0;
+ skb = tcp_write_queue_tail(sk);
+ if (tcp_send_head(sk)) {
+ if (skb->ip_summed == CHECKSUM_NONE)
+ max = mss_now;
+ copy = max - skb->len;
}
- while (seglen > 0) {
- int copy = 0;
- int max = size_goal;
-
- skb = tcp_write_queue_tail(sk);
- if (tcp_send_head(sk)) {
- if (skb->ip_summed == CHECKSUM_NONE)
- max = mss_now;
- copy = max - skb->len;
- }
-
- if (copy <= 0) {
+ if (copy <= 0) {
new_segment:
- /* Allocate new segment. If the interface is SG,
- * allocate skb fitting to single page.
- */
- if (!sk_stream_memory_free(sk))
- goto wait_for_sndbuf;
+ /* Allocate new segment. If the interface is SG,
+ * allocate skb fitting to single page.
+ */
+ if (!sk_stream_memory_free(sk))
+ goto wait_for_sndbuf;
- skb = sk_stream_alloc_skb(sk,
- select_size(sk, sg),
- sk->sk_allocation);
- if (!skb)
- goto wait_for_memory;
+ skb = sk_stream_alloc_skb(sk,
+ select_size(sk, sg),
+ sk->sk_allocation);
+ if (!skb)
+ goto wait_for_memory;
- /*
- * Check whether we can use HW checksum.
- */
- if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
- skb->ip_summed = CHECKSUM_PARTIAL;
+ /*
+ * Check whether we can use HW checksum.
+ */
+ if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
+ skb->ip_summed = CHECKSUM_PARTIAL;
- skb_entail(sk, skb);
- copy = size_goal;
- max = size_goal;
+ skb_entail(sk, skb);
+ copy = size_goal;
+ max = size_goal;
- /* All packets are restored as if they have
- * already been sent. skb_mstamp isn't set to
- * avoid wrong rtt estimation.
- */
- if (tp->repair)
- TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
- }
+ /* All packets are restored as if they have
+ * already been sent. skb_mstamp isn't set to
+ * avoid wrong rtt estimation.
+ */
+ if (tp->repair)
+ TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
+ }
- /* Try to append data to the end of skb. */
- if (copy > seglen)
- copy = seglen;
+ /* Try to append data to the end of skb. */
+ if (copy > iov_iter_count(&msg->msg_iter))
+ copy = iov_iter_count(&msg->msg_iter);
- /* Where to copy to? */
- if (skb_availroom(skb) > 0) {
- /* We have some space in skb head. Superb! */
- copy = min_t(int, copy, skb_availroom(skb));
- err = skb_add_data_nocache(sk, skb, from, copy);
- if (err)
- goto do_fault;
- } else {
- bool merge = true;
- int i = skb_shinfo(skb)->nr_frags;
- struct page_frag *pfrag = sk_page_frag(sk);
+ /* Where to copy to? */
+ if (skb_availroom(skb) > 0) {
+ /* We have some space in skb head. Superb! */
+ copy = min_t(int, copy, skb_availroom(skb));
+ err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
+ if (err)
+ goto do_fault;
+ } else {
+ bool merge = true;
+ int i = skb_shinfo(skb)->nr_frags;
+ struct page_frag *pfrag = sk_page_frag(sk);
- if (!sk_page_frag_refill(sk, pfrag))
- goto wait_for_memory;
+ if (!sk_page_frag_refill(sk, pfrag))
+ goto wait_for_memory;
- if (!skb_can_coalesce(skb, i, pfrag->page,
- pfrag->offset)) {
- if (i == MAX_SKB_FRAGS || !sg) {
- tcp_mark_push(tp, skb);
- goto new_segment;
- }
- merge = false;
+ if (!skb_can_coalesce(skb, i, pfrag->page,
+ pfrag->offset)) {
+ if (i == MAX_SKB_FRAGS || !sg) {
+ tcp_mark_push(tp, skb);
+ goto new_segment;
}
-
- copy = min_t(int, copy, pfrag->size - pfrag->offset);
-
- if (!sk_wmem_schedule(sk, copy))
- goto wait_for_memory;
-
- err = skb_copy_to_page_nocache(sk, from, skb,
- pfrag->page,
- pfrag->offset,
- copy);
- if (err)
- goto do_error;
-
- /* Update the skb. */
- if (merge) {
- skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
- } else {
- skb_fill_page_desc(skb, i, pfrag->page,
- pfrag->offset, copy);
- get_page(pfrag->page);
- }
- pfrag->offset += copy;
+ merge = false;
}
- if (!copied)
- TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
+ copy = min_t(int, copy, pfrag->size - pfrag->offset);
- tp->write_seq += copy;
- TCP_SKB_CB(skb)->end_seq += copy;
- tcp_skb_pcount_set(skb, 0);
+ if (!sk_wmem_schedule(sk, copy))
+ goto wait_for_memory;
- from += copy;
- copied += copy;
- if ((seglen -= copy) == 0 && iovlen == 0) {
- tcp_tx_timestamp(sk, skb);
- goto out;
- }
-
- if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
- continue;
-
- if (forced_push(tp)) {
- tcp_mark_push(tp, skb);
- __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
- } else if (skb == tcp_send_head(sk))
- tcp_push_one(sk, mss_now);
- continue;
-
-wait_for_sndbuf:
- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
-wait_for_memory:
- if (copied)
- tcp_push(sk, flags & ~MSG_MORE, mss_now,
- TCP_NAGLE_PUSH, size_goal);
-
- if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
+ err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
+ pfrag->page,
+ pfrag->offset,
+ copy);
+ if (err)
goto do_error;
- mss_now = tcp_send_mss(sk, &size_goal, flags);
+ /* Update the skb. */
+ if (merge) {
+ skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
+ } else {
+ skb_fill_page_desc(skb, i, pfrag->page,
+ pfrag->offset, copy);
+ get_page(pfrag->page);
+ }
+ pfrag->offset += copy;
}
+
+ if (!copied)
+ TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
+
+ tp->write_seq += copy;
+ TCP_SKB_CB(skb)->end_seq += copy;
+ tcp_skb_pcount_set(skb, 0);
+
+ copied += copy;
+ if (!iov_iter_count(&msg->msg_iter)) {
+ tcp_tx_timestamp(sk, skb);
+ goto out;
+ }
+
+ if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
+ continue;
+
+ if (forced_push(tp)) {
+ tcp_mark_push(tp, skb);
+ __tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
+ } else if (skb == tcp_send_head(sk))
+ tcp_push_one(sk, mss_now);
+ continue;
+
+wait_for_sndbuf:
+ set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+wait_for_memory:
+ if (copied)
+ tcp_push(sk, flags & ~MSG_MORE, mss_now,
+ TCP_NAGLE_PUSH, size_goal);
+
+ if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
+ goto do_error;
+
+ mss_now = tcp_send_mss(sk, &size_goal, flags);
}
out: