From: Paolo Abeni pabeni@redhat.com
[ Upstream commit f70cad1085d1e01d3ec73c1078405f906237feee ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/mptcp/protocol.c | 137 ++++++++++++++++++++++++------------------- 1 file changed, 77 insertions(+), 60 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7f96e0c42a090..a089791414bfb 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1224,6 +1224,7 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp) if (likely(__mptcp_add_ext(skb, gfp))) { skb_reserve(skb, MAX_TCP_HEADER); skb->reserved_tailroom = skb->end - skb->tail; + INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); return skb; } __kfree_skb(skb); @@ -1233,31 +1234,23 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp) return NULL; }
-static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp) +static struct sk_buff *__mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp) { struct sk_buff *skb;
- if (ssk->sk_tx_skb_cache) { - skb = ssk->sk_tx_skb_cache; - if (unlikely(!skb_ext_find(skb, SKB_EXT_MPTCP) && - !__mptcp_add_ext(skb, gfp))) - return false; - return true; - } - skb = __mptcp_do_alloc_tx_skb(sk, gfp); if (!skb) - return false; + return NULL;
if (likely(sk_wmem_schedule(ssk, skb->truesize))) { - ssk->sk_tx_skb_cache = skb; - return true; + tcp_skb_entail(ssk, skb); + return skb; } kfree_skb(skb); - return false; + return NULL; }
-static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held) +static struct sk_buff *mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held) { gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation;
@@ -1287,23 +1280,29 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, struct mptcp_sendmsg_info *info) { u64 data_seq = dfrag->data_seq + info->sent; + int offset = dfrag->offset + info->sent; struct mptcp_sock *msk = mptcp_sk(sk); bool zero_window_probe = false; struct mptcp_ext *mpext = NULL; - struct sk_buff *skb, *tail; - bool must_collapse = false; - int size_bias = 0; - int avail_size; - size_t ret = 0; + bool can_coalesce = false; + bool reuse_skb = true; + struct sk_buff *skb; + size_t copy; + int i;
pr_debug("msk=%p ssk=%p sending dfrag at seq=%llu len=%u already sent=%u", msk, ssk, dfrag->data_seq, dfrag->data_len, info->sent);
+ if (WARN_ON_ONCE(info->sent > info->limit || + info->limit > dfrag->data_len)) + return 0; + /* compute send limit */ info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags); - avail_size = info->size_goal; + copy = info->size_goal; + skb = tcp_write_queue_tail(ssk); - if (skb) { + if (skb && copy > skb->len) { /* 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 @@ -1316,62 +1315,80 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, goto alloc_skb; }
- must_collapse = (info->size_goal > skb->len) && - (skb_shinfo(skb)->nr_frags < sysctl_max_skb_frags); - if (must_collapse) { - size_bias = skb->len; - avail_size = info->size_goal - skb->len; + i = skb_shinfo(skb)->nr_frags; + can_coalesce = skb_can_coalesce(skb, i, dfrag->page, offset); + if (!can_coalesce && i >= sysctl_max_skb_frags) { + tcp_mark_push(tcp_sk(ssk), skb); + goto alloc_skb; } - }
+ copy -= skb->len; + } else { alloc_skb: - if (!must_collapse && - !mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held)) - return 0; + skb = mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held); + if (!skb) + return -ENOMEM; + + i = skb_shinfo(skb)->nr_frags; + reuse_skb = false; + mpext = skb_ext_find(skb, SKB_EXT_MPTCP); + }
/* Zero window and all data acked? Probe. */ - avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size); - if (avail_size == 0) { + copy = mptcp_check_allowed_size(msk, data_seq, copy); + if (copy == 0) { u64 snd_una = READ_ONCE(msk->snd_una);
- if (skb || snd_una != msk->snd_nxt) + if (snd_una != msk->snd_nxt) { + tcp_remove_empty_skb(ssk, tcp_write_queue_tail(ssk)); return 0; + } + zero_window_probe = true; data_seq = snd_una - 1; - avail_size = 1; - } + copy = 1;
- if (WARN_ON_ONCE(info->sent > info->limit || - info->limit > dfrag->data_len)) - return 0; + /* all mptcp-level data is acked, no skbs should be present into the + * ssk write queue + */ + WARN_ON_ONCE(reuse_skb); + }
- ret = info->limit - info->sent; - tail = tcp_build_frag(ssk, avail_size + size_bias, info->flags, - dfrag->page, dfrag->offset + info->sent, &ret); - if (!tail) { - tcp_remove_empty_skb(sk, tcp_write_queue_tail(ssk)); + copy = min_t(size_t, copy, info->limit - info->sent); + if (!sk_wmem_schedule(ssk, copy)) { + tcp_remove_empty_skb(ssk, tcp_write_queue_tail(ssk)); return -ENOMEM; }
- /* if the tail skb is still the cached one, collapsing really happened. - */ - if (skb == tail) { - TCP_SKB_CB(tail)->tcp_flags &= ~TCPHDR_PSH; - mpext->data_len += ret; + if (can_coalesce) { + skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); + } else { + get_page(dfrag->page); + skb_fill_page_desc(skb, i, dfrag->page, offset, copy); + } + + skb->len += copy; + skb->data_len += copy; + skb->truesize += copy; + sk_wmem_queued_add(ssk, copy); + sk_mem_charge(ssk, copy); + skb->ip_summed = CHECKSUM_PARTIAL; + WRITE_ONCE(tcp_sk(ssk)->write_seq, tcp_sk(ssk)->write_seq + copy); + TCP_SKB_CB(skb)->end_seq += copy; + tcp_skb_pcount_set(skb, 0); + + /* on skb reuse we just need to update the DSS len */ + if (reuse_skb) { + TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH; + mpext->data_len += copy; WARN_ON_ONCE(zero_window_probe); goto out; }
- mpext = skb_ext_find(tail, SKB_EXT_MPTCP); - if (WARN_ON_ONCE(!mpext)) { - /* should never reach here, stream corrupted */ - return -EINVAL; - } - memset(mpext, 0, sizeof(*mpext)); mpext->data_seq = data_seq; mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq; - mpext->data_len = ret; + mpext->data_len = copy; mpext->use_map = 1; mpext->dsn64 = 1;
@@ -1380,18 +1397,18 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, mpext->dsn64);
if (zero_window_probe) { - mptcp_subflow_ctx(ssk)->rel_write_seq += ret; + mptcp_subflow_ctx(ssk)->rel_write_seq += copy; mpext->frozen = 1; if (READ_ONCE(msk->csum_enabled)) - mptcp_update_data_checksum(tail, ret); + mptcp_update_data_checksum(skb, copy); tcp_push_pending_frames(ssk); return 0; } out: if (READ_ONCE(msk->csum_enabled)) - mptcp_update_data_checksum(tail, ret); - mptcp_subflow_ctx(ssk)->rel_write_seq += ret; - return ret; + mptcp_update_data_checksum(skb, copy); + mptcp_subflow_ctx(ssk)->rel_write_seq += copy; + return copy; }
#define MPTCP_SEND_BURST_SIZE ((1 << 16) - \