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/include/net/sock.h b/include/net/sock.h
index 1534149..1e45e59 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1803,27 +1803,25 @@ static inline void sk_nocaps_add(struct sock *sk, netdev_features_t flags)
 }
 
 static inline int skb_do_copy_data_nocache(struct sock *sk, struct sk_buff *skb,
-                                          char __user *from, char *to,
+                                          struct iov_iter *from, char *to,
                                           int copy, int offset)
 {
        if (skb->ip_summed == CHECKSUM_NONE) {
-               int err = 0;
-               __wsum csum = csum_and_copy_from_user(from, to, copy, 0, &err);
-               if (err)
-                       return err;
+               __wsum csum = 0;
+               if (csum_and_copy_from_iter(to, copy, &csum, from) != copy)
+                       return -EFAULT;
                skb->csum = csum_block_add(skb->csum, csum, offset);
        } else if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
-               if (!access_ok(VERIFY_READ, from, copy) ||
-                   __copy_from_user_nocache(to, from, copy))
+               if (copy_from_iter_nocache(to, copy, from) != copy)
                        return -EFAULT;
-       } else if (copy_from_user(to, from, copy))
+       } else if (copy_from_iter(to, copy, from) != copy)
                return -EFAULT;
 
        return 0;
 }
 
 static inline int skb_add_data_nocache(struct sock *sk, struct sk_buff *skb,
-                                      char __user *from, int copy)
+                                      struct iov_iter *from, int copy)
 {
        int err, offset = skb->len;
 
@@ -1835,7 +1833,7 @@ static inline int skb_add_data_nocache(struct sock *sk, struct sk_buff *skb,
        return err;
 }
 
-static inline int skb_copy_to_page_nocache(struct sock *sk, char __user *from,
+static inline int skb_copy_to_page_nocache(struct sock *sk, struct iov_iter *from,
                                           struct sk_buff *skb,
                                           struct page *page,
                                           int off, int copy)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3075723..9d72a0f 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1067,11 +1067,10 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
 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 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                        goto out;
                else if (err)
                        goto out_err;
-               offset = copied_syn;
        }
 
        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
@@ -1118,8 +1116,6 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
        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 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
        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;
-
-                       /* 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);
-
-                               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;
-                               }
+               /* 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, &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;
 
-                               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);
+                       if (!skb_can_coalesce(skb, i, pfrag->page,
+                                             pfrag->offset)) {
+                               if (i == MAX_SKB_FRAGS || !sg) {
+                                       tcp_mark_push(tp, skb);
+                                       goto new_segment;
                                }
-                               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;
+                       err = skb_copy_to_page_nocache(sk, &msg->msg_iter, 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;
+               }
 
-                       if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
-                               continue;
+               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 (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);
+               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);
+               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 (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;
+               if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
+                       goto do_error;
 
-                       mss_now = tcp_send_mss(sk, &size_goal, flags);
-               }
+               mss_now = tcp_send_mss(sk, &size_goal, flags);
        }
 
 out:

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 71fb37c..93c7482 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4368,7 +4368,7 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
        if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
                goto err_free;
 
-       if (memcpy_from_msg(skb_put(skb, size), msg, size))
+       if (copy_from_iter(skb_put(skb, size), size, &msg->msg_iter) != size)
                goto err_free;
 
        TCP_SKB_CB(skb)->seq = tcp_sk(sk)->rcv_nxt;

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 20ab06b..722c8bc 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3055,7 +3055,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct tcp_fastopen_request *fo = tp->fastopen_req;
-       int syn_loss = 0, space, err = 0;
+       int syn_loss = 0, space, err = 0, copied;
        unsigned long last_syn_loss = 0;
        struct sk_buff *syn_data;
 
@@ -3093,11 +3093,16 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
                goto fallback;
        syn_data->ip_summed = CHECKSUM_PARTIAL;
        memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));
-       if (unlikely(memcpy_fromiovecend(skb_put(syn_data, space),
-                                        fo->data->msg_iter.iov, 0, space))) {
+       copied = copy_from_iter(skb_put(syn_data, space), space,
+                               &fo->data->msg_iter);
+       if (unlikely(!copied)) {
                kfree_skb(syn_data);
                goto fallback;
        }
+       if (copied != space) {
+               skb_trim(syn_data, copied);
+               space = copied;
+       }
 
        /* No more data pending in inet_wait_for_connect() */
        if (space == fo->size)