diff options
author | Paolo Abeni <pabeni@redhat.com> | 2020-11-16 10:48:10 +0100 |
---|---|---|
committer | Jakub Kicinski <kuba@kernel.org> | 2020-11-16 19:46:07 +0100 |
commit | d9ca1de8c0cd7a8ca2a0506e1741418741848e53 (patch) | |
tree | 6c6acef02362a2693cfc1ed37ce858b57f627685 /net | |
parent | mptcp: refactor shutdown and close (diff) | |
download | linux-d9ca1de8c0cd7a8ca2a0506e1741418741848e53.tar.xz linux-d9ca1de8c0cd7a8ca2a0506e1741418741848e53.zip |
mptcp: move page frag allocation in mptcp_sendmsg()
mptcp_sendmsg() is refactored so that first it copies
the data provided from user space into the send queue,
and then tries to spool the send queue via sendmsg_frag.
There a subtle change in the mptcp level collapsing on
consecutive data fragment: we now allow that only on unsent
data.
The latter don't need to deal with msghdr data anymore
and can be simplified in a relevant way.
snd_nxt and write_seq are now tracked independently.
Overall this allows some relevant cleanup and will
allow sending pending mptcp data on msk una update in
later patch.
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: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r-- | net/mptcp/protocol.c | 406 |
1 files changed, 189 insertions, 217 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index daa51e657db8..9b30c4b39159 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -43,6 +43,7 @@ struct mptcp_skb_cb { static struct percpu_counter mptcp_sockets_allocated; static void __mptcp_destroy_sock(struct sock *sk); +static void __mptcp_check_send_data_fin(struct sock *sk); /* If msk has an initial subflow socket, and the MP_CAPABLE handshake has not * completed yet or has failed, return the subflow socket. @@ -814,6 +815,7 @@ static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk, const struct mptcp_data_frag *df) { return df && pfrag->page == df->page && + pfrag->size - pfrag->offset > 0 && df->data_seq + df->data_len == msk->write_seq; } @@ -864,6 +866,8 @@ static void mptcp_clean_una(struct sock *sk) if (after64(dfrag->data_seq + dfrag->data_len, snd_una)) break; + if (WARN_ON_ONCE(dfrag == msk->first_pending)) + break; dfrag_clear(sk, dfrag); cleaned = true; } @@ -872,12 +876,13 @@ static void mptcp_clean_una(struct sock *sk) if (dfrag && after64(snd_una, dfrag->data_seq)) { u64 delta = snd_una - dfrag->data_seq; - if (WARN_ON_ONCE(delta > dfrag->data_len)) + if (WARN_ON_ONCE(delta > dfrag->already_sent)) goto out; dfrag->data_seq += delta; dfrag->offset += delta; dfrag->data_len -= delta; + dfrag->already_sent -= delta; dfrag_uncharge(sk, delta); cleaned = true; @@ -911,12 +916,23 @@ static void mptcp_clean_una_wakeup(struct sock *sk) */ static bool mptcp_page_frag_refill(struct sock *sk, struct page_frag *pfrag) { + struct mptcp_subflow_context *subflow; + struct mptcp_sock *msk = mptcp_sk(sk); + bool first = true; + if (likely(skb_page_frag_refill(32U + sizeof(struct mptcp_data_frag), pfrag, sk->sk_allocation))) return true; - sk->sk_prot->enter_memory_pressure(sk); sk_stream_moderate_sndbuf(sk); + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + if (first) + tcp_enter_memory_pressure(ssk); + sk_stream_moderate_sndbuf(ssk); + first = false; + } return false; } @@ -932,6 +948,7 @@ mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag, dfrag->data_seq = msk->write_seq; dfrag->overhead = offset - orig_offset + sizeof(struct mptcp_data_frag); dfrag->offset = offset + sizeof(struct mptcp_data_frag); + dfrag->already_sent = 0; dfrag->page = pfrag->page; return dfrag; @@ -940,121 +957,58 @@ mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag, struct mptcp_sendmsg_info { int mss_now; int size_goal; + u16 limit; + u16 sent; + unsigned int flags; }; static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, - struct msghdr *msg, struct mptcp_data_frag *dfrag, + struct mptcp_data_frag *dfrag, struct mptcp_sendmsg_info *info) { - int avail_size, offset, ret, frag_truesize = 0; - bool dfrag_collapsed, can_collapse = false; + u64 data_seq = dfrag->data_seq + info->sent; struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_ext *mpext = NULL; - 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); - if (!retransmission) { - write_seq = &msk->write_seq; - page = pfrag->page; - } else { - write_seq = &dfrag->data_seq; - page = dfrag->page; - } + bool can_collapse = false; + int avail_size; + size_t ret; - /* compute copy limit */ - info->mss_now = tcp_send_mss(ssk, &info->size_goal, msg->msg_flags); + pr_debug("msk=%p ssk=%p sending dfrag at seq=%lld len=%d already sent=%d", + msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent); + + /* compute send limit */ + info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags); avail_size = info->size_goal; skb = tcp_write_queue_tail(ssk); if (skb) { - mpext = skb_ext_find(skb, SKB_EXT_MPTCP); - /* Limit the write to the size available in the * current skb, if any, so that we create at most a new skb. * Explicitly tells TCP internals to avoid collapsing on later * queue management operation, to avoid breaking the ext <-> * SSN association set here */ + mpext = skb_ext_find(skb, SKB_EXT_MPTCP); can_collapse = (info->size_goal - skb->len > 0) && - mptcp_skb_can_collapse_to(*write_seq, skb, mpext); + mptcp_skb_can_collapse_to(data_seq, skb, mpext); if (!can_collapse) TCP_SKB_CB(skb)->eor = 1; else avail_size = info->size_goal - skb->len; } - 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 (WARN_ON_ONCE(info->sent > info->limit || + info->limit > dfrag->data_len)) + return 0; - if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) { - iov_iter_revert(&msg->msg_iter, psize); - return -ENOMEM; - } - } else { - offset = dfrag->offset; - psize = min_t(size_t, dfrag->data_len, avail_size); - } - - tail = tcp_build_frag(ssk, psize, msg->msg_flags, page, offset, &psize); + ret = info->limit - info->sent; + tail = tcp_build_frag(ssk, avail_size, info->flags, dfrag->page, + dfrag->offset + info->sent, &ret); if (!tail) { tcp_remove_empty_skb(sk, tcp_write_queue_tail(ssk)); return -ENOMEM; } - ret = psize; - frag_truesize += 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); - 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; - } - /* if the tail skb is still the cached one, collapsing really happened. */ if (skb == tail) { @@ -1067,7 +1021,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, msk->cached_ext = NULL; memset(mpext, 0, sizeof(*mpext)); - mpext->data_seq = *write_seq; + mpext->data_seq = data_seq; mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq; mpext->data_len = ret; mpext->use_map = 1; @@ -1078,11 +1032,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, mpext->dsn64); out: - if (!retransmission) - pfrag->offset += frag_truesize; - WRITE_ONCE(*write_seq, *write_seq + ret); mptcp_subflow_ctx(ssk)->rel_write_seq += ret; - return ret; } @@ -1210,19 +1160,86 @@ static void ssk_check_wmem(struct mptcp_sock *msk) mptcp_nospace(msk); } -static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) +static void mptcp_push_release(struct sock *sk, struct sock *ssk, + struct mptcp_sendmsg_info *info) +{ + mptcp_set_timeout(sk, ssk); + tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, info->size_goal); + release_sock(ssk); +} + +static void mptcp_push_pending(struct sock *sk, unsigned int flags) { + struct sock *prev_ssk = NULL, *ssk = NULL; struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_sendmsg_info info = { - .mss_now = 0, - .size_goal = 0, + .flags = flags, }; + struct mptcp_data_frag *dfrag; + int len, copied = 0; + u32 sndbuf; + + while ((dfrag = mptcp_send_head(sk))) { + info.sent = dfrag->already_sent; + info.limit = dfrag->data_len; + len = dfrag->data_len - dfrag->already_sent; + while (len > 0) { + int ret = 0; + + prev_ssk = ssk; + __mptcp_flush_join_list(msk); + ssk = mptcp_subflow_get_send(msk, &sndbuf); + + /* do auto tuning */ + if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK) && + sndbuf > READ_ONCE(sk->sk_sndbuf)) + WRITE_ONCE(sk->sk_sndbuf, sndbuf); + + /* try to keep the subflow socket lock across + * consecutive xmit on the same socket + */ + if (ssk != prev_ssk && prev_ssk) + mptcp_push_release(sk, prev_ssk, &info); + if (!ssk) + goto out; + + if (ssk != prev_ssk || !prev_ssk) + lock_sock(ssk); + + ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info); + if (ret <= 0) { + mptcp_push_release(sk, ssk, &info); + goto out; + } + + info.sent += ret; + dfrag->already_sent += ret; + msk->snd_nxt += ret; + msk->snd_burst -= ret; + copied += ret; + len -= ret; + } + WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); + } + + /* at this point we held the socket lock for the last subflow we used */ + if (ssk) + mptcp_push_release(sk, ssk, &info); + +out: + /* start the timer, if it's not pending */ + if (!mptcp_timer_pending(sk)) + mptcp_reset_timer(sk); + if (copied) + __mptcp_check_send_data_fin(sk); +} + +static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) +{ + struct mptcp_sock *msk = mptcp_sk(sk); struct page_frag *pfrag; size_t copied = 0; - struct sock *ssk; int ret = 0; - u32 sndbuf; - bool tx_ok; long timeo; if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL)) @@ -1239,129 +1256,93 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) } pfrag = sk_page_frag(sk); -restart: mptcp_clean_una(sk); - if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) { - ret = -EPIPE; - goto out; - } - - __mptcp_flush_join_list(msk); - ssk = mptcp_subflow_get_send(msk, &sndbuf); - while (!sk_stream_memory_free(sk) || - !ssk || - !mptcp_page_frag_refill(ssk, pfrag)) { - if (ssk) { - /* make sure retransmit timer is - * running before we wait for memory. - * - * The retransmit timer might be needed - * to make the peer send an up-to-date - * MPTCP Ack. - */ - mptcp_set_timeout(sk, ssk); - if (!mptcp_timer_pending(sk)) - mptcp_reset_timer(sk); - } - - mptcp_nospace(msk); - ret = sk_stream_wait_memory(sk, &timeo); - if (ret) - goto out; - - mptcp_clean_una(sk); + while (msg_data_left(msg)) { + struct mptcp_data_frag *dfrag; + int frag_truesize = 0; + bool dfrag_collapsed; + size_t psize, offset; - ssk = mptcp_subflow_get_send(msk, &sndbuf); - if (list_empty(&msk->conn_list)) { - ret = -ENOTCONN; + if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) { + ret = -EPIPE; goto out; } - } - /* do auto tuning */ - if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK) && - sndbuf > READ_ONCE(sk->sk_sndbuf)) - WRITE_ONCE(sk->sk_sndbuf, sndbuf); - - pr_debug("conn_list->subflow=%p", ssk); - - lock_sock(ssk); - tx_ok = msg_data_left(msg); - while (tx_ok) { - ret = mptcp_sendmsg_frag(sk, ssk, msg, NULL, &info); - if (ret < 0) { - if (ret == -EAGAIN && timeo > 0) { - mptcp_set_timeout(sk, ssk); - release_sock(ssk); - goto restart; + /* reuse tail pfrag, if possible, or carve a new one from the + * page allocator + */ + dfrag = mptcp_pending_tail(sk); + dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag); + if (!dfrag_collapsed) { + if (!sk_stream_memory_free(sk)) { + mptcp_push_pending(sk, msg->msg_flags); + if (!sk_stream_memory_free(sk)) + goto wait_for_memory; } - break; + if (!mptcp_page_frag_refill(sk, pfrag)) + goto wait_for_memory; + + dfrag = mptcp_carve_data_frag(msk, pfrag, pfrag->offset); + frag_truesize = dfrag->overhead; } - /* burst can be negative, we will try move to the next subflow - * at selection time, if possible. + /* we do not bound vs wspace, to allow a single packet. + * memory accounting will prevent execessive memory usage + * anyway */ - msk->snd_burst -= ret; - copied += ret; - - tx_ok = msg_data_left(msg); - if (!tx_ok) - break; - - if (!sk_stream_memory_free(ssk) || - !mptcp_page_frag_refill(ssk, pfrag) || - !mptcp_ext_cache_refill(msk)) { - tcp_push(ssk, msg->msg_flags, info.mss_now, - tcp_sk(ssk)->nonagle, info.size_goal); - mptcp_set_timeout(sk, ssk); - release_sock(ssk); - goto restart; + offset = dfrag->offset + dfrag->data_len; + psize = pfrag->size - offset; + psize = min_t(size_t, psize, msg_data_left(msg)); + if (!sk_wmem_schedule(sk, psize + frag_truesize)) + goto wait_for_memory; + + if (copy_page_from_iter(dfrag->page, offset, psize, + &msg->msg_iter) != psize) { + ret = -EFAULT; + goto out; } - /* memory is charged to mptcp level socket as well, i.e. - * if msg is very large, mptcp socket may run out of buffer - * space. mptcp_clean_una() will release data that has - * been acked at mptcp level in the mean time, so there is - * a good chance we can continue sending data right away. - * - * Normally, when the tcp subflow can accept more data, then - * so can the MPTCP socket. However, we need to cope with - * peers that might lag behind in their MPTCP-level - * acknowledgements, i.e. data might have been acked at - * tcp level only. So, we must also check the MPTCP socket - * limits before we send more data. + /* data successfully copied into the write queue */ + copied += psize; + dfrag->data_len += psize; + frag_truesize += psize; + pfrag->offset += frag_truesize; + WRITE_ONCE(msk->write_seq, msk->write_seq + psize); + + /* charge data on mptcp pending queue to the msk socket + * Note: we charge such data both to sk and ssk */ - if (unlikely(!sk_stream_memory_free(sk))) { - tcp_push(ssk, msg->msg_flags, info.mss_now, - tcp_sk(ssk)->nonagle, info.size_goal); - mptcp_clean_una(sk); - if (!sk_stream_memory_free(sk)) { - /* can't send more for now, need to wait for - * MPTCP-level ACKs from peer. - * - * Wakeup will happen via mptcp_clean_una(). - */ - mptcp_set_timeout(sk, ssk); - release_sock(ssk); - goto restart; - } + sk_wmem_queued_add(sk, frag_truesize); + sk->sk_forward_alloc -= frag_truesize; + if (!dfrag_collapsed) { + get_page(dfrag->page); + list_add_tail(&dfrag->list, &msk->rtx_queue); + if (!msk->first_pending) + WRITE_ONCE(msk->first_pending, dfrag); } - } + pr_debug("msk=%p dfrag at seq=%lld len=%d sent=%d new=%d", msk, + dfrag->data_seq, dfrag->data_len, dfrag->already_sent, + !dfrag_collapsed); - mptcp_set_timeout(sk, ssk); - if (copied) { - tcp_push(ssk, msg->msg_flags, info.mss_now, - tcp_sk(ssk)->nonagle, info.size_goal); + if (!mptcp_ext_cache_refill(msk)) + goto wait_for_memory; + continue; - /* start the timer, if it's not pending */ - if (!mptcp_timer_pending(sk)) +wait_for_memory: + mptcp_nospace(msk); + mptcp_clean_una(sk); + if (mptcp_timer_pending(sk)) mptcp_reset_timer(sk); + ret = sk_stream_wait_memory(sk, &timeo); + if (ret) + goto out; } - release_sock(ssk); + if (copied) + mptcp_push_pending(sk, msg->msg_flags); + out: - msk->snd_nxt = msk->write_seq; ssk_check_wmem(msk); release_sock(sk); return copied ? : ret; @@ -1700,7 +1681,7 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk) sock_owned_by_me((const struct sock *)msk); if (__mptcp_check_fallback(msk)) - return msk->first; + return NULL; mptcp_for_each_subflow(msk, subflow) { struct sock *ssk = mptcp_subflow_tcp_sock(subflow); @@ -1843,12 +1824,7 @@ static void mptcp_worker(struct work_struct *work) struct sock *ssk, *sk = &msk->sk.icsk_inet.sk; struct mptcp_sendmsg_info info = {}; struct mptcp_data_frag *dfrag; - int orig_len, orig_offset; - u64 orig_write_seq; size_t copied = 0; - struct msghdr msg = { - .msg_flags = MSG_DONTWAIT, - }; int state, ret; lock_sock(sk); @@ -1901,18 +1877,17 @@ static void mptcp_worker(struct work_struct *work) lock_sock(ssk); - orig_len = dfrag->data_len; - orig_offset = dfrag->offset; - orig_write_seq = dfrag->data_seq; - while (dfrag->data_len > 0) { - ret = mptcp_sendmsg_frag(sk, ssk, &msg, dfrag, &info); + /* limit retransmission to the bytes already sent on some subflows */ + info.sent = 0; + info.limit = dfrag->already_sent; + while (info.sent < dfrag->already_sent) { + ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info); if (ret < 0) break; MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS); copied += ret; - dfrag->data_len -= ret; - dfrag->offset += ret; + info.sent += ret; if (!mptcp_ext_cache_refill(msk)) break; @@ -1921,10 +1896,6 @@ static void mptcp_worker(struct work_struct *work) tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle, info.size_goal); - dfrag->data_seq = orig_write_seq; - dfrag->offset = orig_offset; - dfrag->data_len = orig_len; - mptcp_set_timeout(sk, ssk); release_sock(ssk); @@ -1996,6 +1967,7 @@ static void __mptcp_clear_xmit(struct sock *sk) sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer); + WRITE_ONCE(msk->first_pending, NULL); list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) dfrag_clear(sk, dfrag); } |