| Message ID | 20230411160902.4134381-8-dhowells@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | splice, net: Replace sendpage with sendmsg(MSG_SPLICE_PAGES), part 1 | expand |
On Tue, Apr 11, 2023 at 6:09 PM David Howells <dhowells@redhat.com> wrote: > > Make TCP's sendmsg() support MSG_SPLICE_PAGES. This causes pages to be > spliced or copied (if it cannot be spliced) from the source iterator. > > This allows ->sendpage() to be replaced by something that can handle > multiple multipage folios in a single transaction. > > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Eric Dumazet <edumazet@google.com> > cc: "David S. Miller" <davem@davemloft.net> > cc: David Ahern <dsahern@kernel.org> > cc: Jakub Kicinski <kuba@kernel.org> > cc: Paolo Abeni <pabeni@redhat.com> > cc: Jens Axboe <axboe@kernel.dk> > cc: Matthew Wilcox <willy@infradead.org> > cc: netdev@vger.kernel.org > --- > > Notes: > ver #6) > - Use common helper. > > net/ipv4/tcp.c | 43 ++++++++++++++++++++++++++++++++++++------- > 1 file changed, 36 insertions(+), 7 deletions(-) > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index fd68d49490f2..0b2213da5aaf 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -1221,7 +1221,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) > int flags, err, copied = 0; > int mss_now = 0, size_goal, copied_syn = 0; > int process_backlog = 0; > - bool zc = false; > + int zc = 0; > long timeo; > > flags = msg->msg_flags; > @@ -1232,17 +1232,22 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) > if (msg->msg_ubuf) { > uarg = msg->msg_ubuf; > net_zcopy_get(uarg); > - zc = sk->sk_route_caps & NETIF_F_SG; > + if (sk->sk_route_caps & NETIF_F_SG) > + zc = 1; zc is set to 0, 1, MSG_ZEROCOPY , MSG_SPLICE_PAGES I find this a bit confusing. Maybe use a private enum ? > } else if (sock_flag(sk, SOCK_ZEROCOPY)) { > uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb)); > if (!uarg) { > err = -ENOBUFS; > goto out_err; > } > - zc = sk->sk_route_caps & NETIF_F_SG; > - if (!zc) > + if (sk->sk_route_caps & NETIF_F_SG) > + zc = MSG_ZEROCOPY; > + else > uarg_to_msgzc(uarg)->zerocopy = 0; > } > + } else if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES) && size) { > + if (sk->sk_route_caps & NETIF_F_SG) > + zc = MSG_SPLICE_PAGES;
Eric Dumazet <edumazet@google.com> wrote: > > - zc = sk->sk_route_caps & NETIF_F_SG; > > + if (sk->sk_route_caps & NETIF_F_SG) > > + zc = 1; > > zc is set to 0, 1, MSG_ZEROCOPY , MSG_SPLICE_PAGES > > I find this a bit confusing. Maybe use a private enum ? Meh. That should be "zc = MSG_ZEROCOPY;". Will fix. David
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index fd68d49490f2..0b2213da5aaf 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1221,7 +1221,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) int flags, err, copied = 0; int mss_now = 0, size_goal, copied_syn = 0; int process_backlog = 0; - bool zc = false; + int zc = 0; long timeo; flags = msg->msg_flags; @@ -1232,17 +1232,22 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (msg->msg_ubuf) { uarg = msg->msg_ubuf; net_zcopy_get(uarg); - zc = sk->sk_route_caps & NETIF_F_SG; + if (sk->sk_route_caps & NETIF_F_SG) + zc = 1; } else if (sock_flag(sk, SOCK_ZEROCOPY)) { uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb)); if (!uarg) { err = -ENOBUFS; goto out_err; } - zc = sk->sk_route_caps & NETIF_F_SG; - if (!zc) + if (sk->sk_route_caps & NETIF_F_SG) + zc = MSG_ZEROCOPY; + else uarg_to_msgzc(uarg)->zerocopy = 0; } + } else if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES) && size) { + if (sk->sk_route_caps & NETIF_F_SG) + zc = MSG_SPLICE_PAGES; } if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect) && @@ -1305,7 +1310,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) goto do_error; while (msg_data_left(msg)) { - int copy = 0; + ssize_t copy = 0; skb = tcp_write_queue_tail(sk); if (skb) @@ -1346,7 +1351,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (copy > msg_data_left(msg)) copy = msg_data_left(msg); - if (!zc) { + if (zc == 0) { bool merge = true; int i = skb_shinfo(skb)->nr_frags; struct page_frag *pfrag = sk_page_frag(sk); @@ -1391,7 +1396,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) page_ref_inc(pfrag->page); } pfrag->offset += copy; - } else { + } else if (zc == MSG_ZEROCOPY) { /* First append to a fragless skb builds initial * pure zerocopy skb */ @@ -1412,6 +1417,30 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (err < 0) goto do_error; copy = err; + } else if (zc == MSG_SPLICE_PAGES) { + /* Splice in data if we can; copy if we can't. */ + if (tcp_downgrade_zcopy_pure(sk, skb)) + goto wait_for_space; + copy = tcp_wmem_schedule(sk, copy); + if (!copy) + goto wait_for_space; + + err = skb_splice_from_iter(skb, &msg->msg_iter, copy, + sk->sk_allocation); + if (err < 0) { + if (err == -EMSGSIZE) { + tcp_mark_push(tp, skb); + goto new_segment; + } + goto do_error; + } + copy = err; + + if (!(flags & MSG_NO_SHARED_FRAGS)) + skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG; + + sk_wmem_queued_add(sk, copy); + sk_mem_charge(sk, copy); } if (!copied)
Make TCP's sendmsg() support MSG_SPLICE_PAGES. This causes pages to be spliced or copied (if it cannot be spliced) from the source iterator. This allows ->sendpage() to be replaced by something that can handle multiple multipage folios in a single transaction. Signed-off-by: David Howells <dhowells@redhat.com> cc: Eric Dumazet <edumazet@google.com> cc: "David S. Miller" <davem@davemloft.net> cc: David Ahern <dsahern@kernel.org> cc: Jakub Kicinski <kuba@kernel.org> cc: Paolo Abeni <pabeni@redhat.com> cc: Jens Axboe <axboe@kernel.dk> cc: Matthew Wilcox <willy@infradead.org> cc: netdev@vger.kernel.org --- Notes: ver #6) - Use common helper. net/ipv4/tcp.c | 43 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 7 deletions(-)