diff options
Diffstat (limited to 'net/mptcp')
| -rw-r--r-- | net/mptcp/protocol.c | 75 |
1 files changed, 60 insertions, 15 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index ad9c73cc20e1..0b21ae25bd0f 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -122,14 +122,27 @@ 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) +{ + 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; +} + static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, - struct msghdr *msg, long *timeo) + struct msghdr *msg, long *timeo, int *pmss_now, + int *ps_goal) { - int mss_now = 0, size_goal = 0, ret = 0; + int mss_now, avail_size, size_goal, ret; struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_ext *mpext = NULL; + struct sk_buff *skb, *tail; + bool can_collapse = false; struct page_frag *pfrag; - struct sk_buff *skb; size_t psize; /* use the mptcp page cache so that we can easily move the data @@ -145,8 +158,29 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, /* compute copy limit */ mss_now = tcp_send_mss(ssk, &size_goal, msg->msg_flags); - psize = min_t(int, pfrag->size - pfrag->offset, size_goal); + *pmss_now = mss_now; + *ps_goal = size_goal; + avail_size = 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 + */ + can_collapse = (size_goal - skb->len > 0) && + mptcp_skb_can_collapse_to(msk, skb, mpext); + if (!can_collapse) + TCP_SKB_CB(skb)->eor = 1; + else + avail_size = size_goal - skb->len; + } + psize = min_t(size_t, pfrag->size - pfrag->offset, avail_size); + /* Copy to page */ pr_debug("left=%zu", msg_data_left(msg)); psize = copy_page_from_iter(pfrag->page, pfrag->offset, min_t(size_t, msg_data_left(msg), psize), @@ -155,14 +189,9 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, if (!psize) return -EINVAL; - /* Mark the end of the previous write so the beginning of the - * next write (with its own mptcp skb extension data) is not - * collapsed. + /* tell the TCP stack to delay the push so that we can safely + * access the skb after the sendpages call */ - skb = tcp_write_queue_tail(ssk); - if (skb) - TCP_SKB_CB(skb)->eor = 1; - ret = do_tcp_sendpages(ssk, pfrag->page, pfrag->offset, psize, msg->msg_flags | MSG_SENDPAGE_NOTLAST); if (ret <= 0) @@ -170,6 +199,18 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, if (unlikely(ret < psize)) iov_iter_revert(&msg->msg_iter, psize - ret); + /* 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 + * hdr on tail can be transmitted, freed and re-allocated by the + * do_tcp_sendpages() call + */ + tail = tcp_write_queue_tail(ssk); + if (mpext && tail && mpext == skb_ext_find(tail, SKB_EXT_MPTCP)) { + WARN_ON_ONCE(!can_collapse); + mpext->data_len += ret; + goto out; + } + skb = tcp_write_queue_tail(ssk); mpext = __skb_ext_set(skb, SKB_EXT_MPTCP, msk->cached_ext); msk->cached_ext = NULL; @@ -185,11 +226,11 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, mpext->data_seq, mpext->subflow_seq, mpext->data_len, mpext->dsn64); +out: pfrag->offset += ret; msk->write_seq += ret; mptcp_subflow_ctx(ssk)->rel_write_seq += ret; - tcp_push(ssk, msg->msg_flags, mss_now, tcp_sk(ssk)->nonagle, size_goal); return ret; } @@ -212,11 +253,11 @@ static void ssk_check_wmem(struct mptcp_sock *msk, struct sock *ssk) static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) { + int mss_now = 0, size_goal = 0, ret = 0; struct mptcp_sock *msk = mptcp_sk(sk); struct socket *ssock; size_t copied = 0; struct sock *ssk; - int ret = 0; long timeo; if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL)) @@ -243,15 +284,19 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) lock_sock(ssk); while (msg_data_left(msg)) { - ret = mptcp_sendmsg_frag(sk, ssk, msg, &timeo); + ret = mptcp_sendmsg_frag(sk, ssk, msg, &timeo, &mss_now, + &size_goal); if (ret < 0) break; copied += ret; } - if (copied > 0) + if (copied) { ret = copied; + tcp_push(ssk, msg->msg_flags, mss_now, tcp_sk(ssk)->nonagle, + size_goal); + } ssk_check_wmem(msk, ssk); release_sock(ssk); |