diff options
author | Paolo Abeni <pabeni@redhat.com> | 2020-03-27 14:48:47 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2020-03-29 22:14:48 -0700 |
commit | 3f8e0aae1796363442f6d0b7bc2210a6eecffb2d (patch) | |
tree | 8cad4b480a2d2ec3951109f60fdd47349f479dc6 /net/mptcp | |
parent | 7948f6cc9951f00aeb8edc51fafbb7450f61d62c (diff) | |
download | linux-3f8e0aae1796363442f6d0b7bc2210a6eecffb2d.tar.bz2 |
mptcp: rework mptcp_sendmsg_frag to accept optional dfrag
This will simplify mptcp-level retransmission implementation
in the next patch. If dfrag is provided by the caller, skip
kernel space memory allocation and use data and metadata
provided by the dfrag itself.
Because a peer could ack data at TCP level but refrain from
sending mptcp-level ACKs, we could grow the mptcp socket
backlog indefinitely.
We should thus block mptcp_sendmsg until the peer has acked some of the
sent data.
In order to be able to do so, increment the mptcp socket wmem_queued
counter on memory allocation and decrement it when releasing the memory
on mptcp-level ack reception.
Because TCP performns sndbuf auto-tuning up to tcp_wmem_max[2], make
this the mptcp sk_sndbuf limit.
In the future we could add experiment with autotuning as TCP does in
tcp_sndbuf_expand().
v2 -> v3:
- remove 'inline' in foo.c files (David S. Miller)
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp')
-rw-r--r-- | net/mptcp/protocol.c | 123 |
1 files changed, 74 insertions, 49 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 1c93e76f0a59..b785d4a3766c 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -316,15 +316,15 @@ static struct sock *mptcp_subflow_recv_lookup(const struct mptcp_sock *msk) return NULL; } -static inline bool mptcp_skb_can_collapse_to(const struct mptcp_sock *msk, - const struct sk_buff *skb, - const struct mptcp_ext *mpext) +static bool mptcp_skb_can_collapse_to(u64 write_seq, + const struct sk_buff *skb, + const struct mptcp_ext *mpext) { if (!tcp_skb_can_collapse_to(skb)) return false; /* can collapse only if MPTCP level sequence is in order */ - return mpext && mpext->data_seq + mpext->data_len == msk->write_seq; + return mpext && mpext->data_seq + mpext->data_len == write_seq; } static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk, @@ -417,23 +417,28 @@ mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag, } static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, - struct msghdr *msg, long *timeo, int *pmss_now, + struct msghdr *msg, struct mptcp_data_frag *dfrag, + long *timeo, int *pmss_now, int *ps_goal) { int mss_now, avail_size, size_goal, offset, ret, frag_truesize = 0; bool dfrag_collapsed, can_collapse = false; struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_ext *mpext = NULL; - struct mptcp_data_frag *dfrag; + bool retransmission = !!dfrag; struct sk_buff *skb, *tail; struct page_frag *pfrag; + struct page *page; + u64 *write_seq; size_t psize; /* use the mptcp page cache so that we can easily move the data * from one substream to another, but do per subflow memory accounting + * Note: pfrag is used only !retransmission, but the compiler if + * fooled into a warning if we don't init here */ pfrag = sk_page_frag(sk); - while (!mptcp_page_frag_refill(ssk, pfrag) || + while ((!retransmission && !mptcp_page_frag_refill(ssk, pfrag)) || !mptcp_ext_cache_refill(msk)) { ret = sk_stream_wait_memory(ssk, timeo); if (ret) @@ -447,6 +452,13 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, if (unlikely(__mptcp_needs_tcp_fallback(msk))) return 0; } + if (!retransmission) { + write_seq = &msk->write_seq; + page = pfrag->page; + } else { + write_seq = &dfrag->data_seq; + page = dfrag->page; + } /* compute copy limit */ mss_now = tcp_send_mss(ssk, &size_goal, msg->msg_flags); @@ -464,63 +476,74 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, * SSN association set here */ can_collapse = (size_goal - skb->len > 0) && - mptcp_skb_can_collapse_to(msk, skb, mpext); + mptcp_skb_can_collapse_to(*write_seq, skb, mpext); if (!can_collapse) TCP_SKB_CB(skb)->eor = 1; else avail_size = size_goal - skb->len; } - /* reuse tail pfrag, if possible, or carve a new one from the page - * allocator - */ - dfrag = mptcp_rtx_tail(sk); - offset = pfrag->offset; - dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag); - if (!dfrag_collapsed) { - dfrag = mptcp_carve_data_frag(msk, pfrag, offset); + if (!retransmission) { + /* reuse tail pfrag, if possible, or carve a new one from the + * page allocator + */ + dfrag = mptcp_rtx_tail(sk); + offset = pfrag->offset; + dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag); + if (!dfrag_collapsed) { + dfrag = mptcp_carve_data_frag(msk, pfrag, offset); + offset = dfrag->offset; + frag_truesize = dfrag->overhead; + } + psize = min_t(size_t, pfrag->size - offset, avail_size); + + /* Copy to page */ + pr_debug("left=%zu", msg_data_left(msg)); + psize = copy_page_from_iter(pfrag->page, offset, + min_t(size_t, msg_data_left(msg), + psize), + &msg->msg_iter); + pr_debug("left=%zu", msg_data_left(msg)); + if (!psize) + return -EINVAL; + + if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) + return -ENOMEM; + } else { offset = dfrag->offset; - frag_truesize = dfrag->overhead; + psize = min_t(size_t, dfrag->data_len, avail_size); } - psize = min_t(size_t, pfrag->size - offset, avail_size); - - /* Copy to page */ - pr_debug("left=%zu", msg_data_left(msg)); - psize = copy_page_from_iter(pfrag->page, offset, - min_t(size_t, msg_data_left(msg), psize), - &msg->msg_iter); - pr_debug("left=%zu", msg_data_left(msg)); - if (!psize) - return -EINVAL; - - if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) - return -ENOMEM; /* tell the TCP stack to delay the push so that we can safely * access the skb after the sendpages call */ - ret = do_tcp_sendpages(ssk, pfrag->page, offset, psize, + ret = do_tcp_sendpages(ssk, page, offset, psize, msg->msg_flags | MSG_SENDPAGE_NOTLAST); if (ret <= 0) return ret; frag_truesize += ret; - if (unlikely(ret < psize)) - iov_iter_revert(&msg->msg_iter, psize - ret); + if (!retransmission) { + if (unlikely(ret < psize)) + iov_iter_revert(&msg->msg_iter, psize - ret); - /* send successful, keep track of sent data for mptcp-level - * retransmission - */ - dfrag->data_len += ret; - if (!dfrag_collapsed) { - get_page(dfrag->page); - list_add_tail(&dfrag->list, &msk->rtx_queue); - } + /* send successful, keep track of sent data for mptcp-level + * retransmission + */ + dfrag->data_len += ret; + if (!dfrag_collapsed) { + get_page(dfrag->page); + list_add_tail(&dfrag->list, &msk->rtx_queue); + sk_wmem_queued_add(sk, frag_truesize); + } else { + sk_wmem_queued_add(sk, ret); + } - /* charge data on mptcp rtx queue to the master socket - * Note: we charge such data both to sk and ssk - */ - sk->sk_forward_alloc -= frag_truesize; + /* charge data on mptcp rtx queue to the master socket + * Note: we charge such data both to sk and ssk + */ + sk->sk_forward_alloc -= frag_truesize; + } /* if the tail skb extension is still the cached one, collapsing * really happened. Note: we can't check for 'same skb' as the sk_buff @@ -539,7 +562,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, msk->cached_ext = NULL; memset(mpext, 0, sizeof(*mpext)); - mpext->data_seq = msk->write_seq; + mpext->data_seq = *write_seq; mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq; mpext->data_len = ret; mpext->use_map = 1; @@ -550,8 +573,9 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, mpext->dsn64); out: - pfrag->offset += frag_truesize; - msk->write_seq += ret; + if (!retransmission) + pfrag->offset += frag_truesize; + *write_seq += ret; mptcp_subflow_ctx(ssk)->rel_write_seq += ret; return ret; @@ -663,7 +687,7 @@ fallback: lock_sock(ssk); while (msg_data_left(msg)) { - ret = mptcp_sendmsg_frag(sk, ssk, msg, &timeo, &mss_now, + ret = mptcp_sendmsg_frag(sk, ssk, msg, NULL, &timeo, &mss_now, &size_goal); if (ret < 0) break; @@ -974,6 +998,7 @@ static int mptcp_init_sock(struct sock *sk) return ret; sk_sockets_allocated_inc(sk); + sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[2]; if (!mptcp_is_enabled(sock_net(sk))) return -ENOPROTOOPT; |