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mptcp: stop relying on tcp_tx_skb_cache
We want to revert the skb TX cache, but MPTCP is currently using it unconditionally. Rework the MPTCP tx code, so that tcp_tx_skb_cache is not needed anymore: do the whole coalescing check, skb allocation skb initialization/update inside mptcp_sendmsg_frag(), quite alike the current TCP code. Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni
David S. Miller
parent
04d8825c30
commit
f70cad1085
1 changed files with 77 additions and 60 deletions
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@ -1224,6 +1224,7 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
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if (likely(__mptcp_add_ext(skb, gfp))) {
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skb_reserve(skb, MAX_TCP_HEADER);
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skb->reserved_tailroom = skb->end - skb->tail;
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INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
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return skb;
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}
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__kfree_skb(skb);
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@ -1233,31 +1234,23 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp)
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return NULL;
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}
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static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
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static struct sk_buff *__mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
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{
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struct sk_buff *skb;
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if (ssk->sk_tx_skb_cache) {
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skb = ssk->sk_tx_skb_cache;
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if (unlikely(!skb_ext_find(skb, SKB_EXT_MPTCP) &&
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!__mptcp_add_ext(skb, gfp)))
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return false;
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return true;
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}
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skb = __mptcp_do_alloc_tx_skb(sk, gfp);
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if (!skb)
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return false;
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return NULL;
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if (likely(sk_wmem_schedule(ssk, skb->truesize))) {
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ssk->sk_tx_skb_cache = skb;
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return true;
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tcp_skb_entail(ssk, skb);
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return skb;
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}
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kfree_skb(skb);
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return false;
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return NULL;
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}
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static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held)
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static struct sk_buff *mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held)
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{
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gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation;
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@ -1287,23 +1280,29 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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struct mptcp_sendmsg_info *info)
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{
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u64 data_seq = dfrag->data_seq + info->sent;
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int offset = dfrag->offset + info->sent;
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struct mptcp_sock *msk = mptcp_sk(sk);
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bool zero_window_probe = false;
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struct mptcp_ext *mpext = NULL;
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struct sk_buff *skb, *tail;
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bool must_collapse = false;
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int size_bias = 0;
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int avail_size;
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size_t ret = 0;
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bool can_coalesce = false;
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bool reuse_skb = true;
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struct sk_buff *skb;
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size_t copy;
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int i;
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pr_debug("msk=%p ssk=%p sending dfrag at seq=%llu len=%u already sent=%u",
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msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent);
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if (WARN_ON_ONCE(info->sent > info->limit ||
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info->limit > dfrag->data_len))
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return 0;
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/* compute send limit */
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info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags);
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avail_size = info->size_goal;
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copy = info->size_goal;
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skb = tcp_write_queue_tail(ssk);
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if (skb) {
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if (skb && copy > skb->len) {
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/* Limit the write to the size available in the
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* current skb, if any, so that we create at most a new skb.
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* Explicitly tells TCP internals to avoid collapsing on later
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@ -1316,62 +1315,80 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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goto alloc_skb;
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}
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must_collapse = (info->size_goal > skb->len) &&
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(skb_shinfo(skb)->nr_frags < sysctl_max_skb_frags);
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if (must_collapse) {
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size_bias = skb->len;
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avail_size = info->size_goal - skb->len;
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i = skb_shinfo(skb)->nr_frags;
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can_coalesce = skb_can_coalesce(skb, i, dfrag->page, offset);
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if (!can_coalesce && i >= sysctl_max_skb_frags) {
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tcp_mark_push(tcp_sk(ssk), skb);
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goto alloc_skb;
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}
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}
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copy -= skb->len;
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} else {
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alloc_skb:
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if (!must_collapse &&
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!mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held))
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return 0;
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skb = mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held);
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if (!skb)
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return -ENOMEM;
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i = skb_shinfo(skb)->nr_frags;
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reuse_skb = false;
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mpext = skb_ext_find(skb, SKB_EXT_MPTCP);
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}
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/* Zero window and all data acked? Probe. */
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avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);
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if (avail_size == 0) {
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copy = mptcp_check_allowed_size(msk, data_seq, copy);
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if (copy == 0) {
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u64 snd_una = READ_ONCE(msk->snd_una);
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if (skb || snd_una != msk->snd_nxt)
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if (snd_una != msk->snd_nxt) {
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tcp_remove_empty_skb(ssk, tcp_write_queue_tail(ssk));
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return 0;
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}
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zero_window_probe = true;
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data_seq = snd_una - 1;
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avail_size = 1;
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copy = 1;
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/* all mptcp-level data is acked, no skbs should be present into the
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* ssk write queue
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*/
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WARN_ON_ONCE(reuse_skb);
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}
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if (WARN_ON_ONCE(info->sent > info->limit ||
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info->limit > dfrag->data_len))
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return 0;
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ret = info->limit - info->sent;
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tail = tcp_build_frag(ssk, avail_size + size_bias, info->flags,
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dfrag->page, dfrag->offset + info->sent, &ret);
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if (!tail) {
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tcp_remove_empty_skb(sk, tcp_write_queue_tail(ssk));
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copy = min_t(size_t, copy, info->limit - info->sent);
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if (!sk_wmem_schedule(ssk, copy)) {
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tcp_remove_empty_skb(ssk, tcp_write_queue_tail(ssk));
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return -ENOMEM;
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}
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/* if the tail skb is still the cached one, collapsing really happened.
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*/
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if (skb == tail) {
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TCP_SKB_CB(tail)->tcp_flags &= ~TCPHDR_PSH;
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mpext->data_len += ret;
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WARN_ON_ONCE(zero_window_probe);
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goto out;
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if (can_coalesce) {
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skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
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} else {
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get_page(dfrag->page);
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skb_fill_page_desc(skb, i, dfrag->page, offset, copy);
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}
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mpext = skb_ext_find(tail, SKB_EXT_MPTCP);
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if (WARN_ON_ONCE(!mpext)) {
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/* should never reach here, stream corrupted */
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return -EINVAL;
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skb->len += copy;
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skb->data_len += copy;
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skb->truesize += copy;
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sk_wmem_queued_add(ssk, copy);
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sk_mem_charge(ssk, copy);
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skb->ip_summed = CHECKSUM_PARTIAL;
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WRITE_ONCE(tcp_sk(ssk)->write_seq, tcp_sk(ssk)->write_seq + copy);
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TCP_SKB_CB(skb)->end_seq += copy;
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tcp_skb_pcount_set(skb, 0);
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/* on skb reuse we just need to update the DSS len */
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if (reuse_skb) {
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
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mpext->data_len += copy;
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WARN_ON_ONCE(zero_window_probe);
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goto out;
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}
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memset(mpext, 0, sizeof(*mpext));
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mpext->data_seq = data_seq;
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mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq;
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mpext->data_len = ret;
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mpext->data_len = copy;
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mpext->use_map = 1;
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mpext->dsn64 = 1;
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@ -1380,18 +1397,18 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
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mpext->dsn64);
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if (zero_window_probe) {
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mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
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mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
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mpext->frozen = 1;
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if (READ_ONCE(msk->csum_enabled))
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mptcp_update_data_checksum(tail, ret);
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mptcp_update_data_checksum(skb, copy);
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tcp_push_pending_frames(ssk);
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return 0;
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}
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out:
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if (READ_ONCE(msk->csum_enabled))
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mptcp_update_data_checksum(tail, ret);
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mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
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return ret;
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mptcp_update_data_checksum(skb, copy);
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mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
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return copy;
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}
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#define MPTCP_SEND_BURST_SIZE ((1 << 16) - \
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