| Message ID | 20240530233616.85897-2-kuba@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 071115301838c6c265065dd5d6bf43a9a987a550 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | tcp: refactor skb_cmp_decrypted() checks | expand |
On Fri, May 31, 2024 at 1:36 AM Jakub Kicinski <kuba@kernel.org> wrote: > > tcp_skb_can_collapse() checks for conditions which don't make > sense on input. Because of this we ended up sprinkling a few > pairs of mptcp_skb_can_collapse() and skb_cmp_decrypted() calls > on the input path. Group them in a new helper. This should make > it less likely that someone will check mptcp and not decrypted > or vice versa when adding new code. > > This implicitly adds a decrypted check early in tcp_collapse(). > AFAIU this will very slightly increase our ability to collapse > packets under memory pressure, not a real bug. > > Signed-off-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com>
Hi Jakub, On 31/05/2024 01:36, Jakub Kicinski wrote: > tcp_skb_can_collapse() checks for conditions which don't make > sense on input. Because of this we ended up sprinkling a few > pairs of mptcp_skb_can_collapse() and skb_cmp_decrypted() calls > on the input path. Group them in a new helper. This should make > it less likely that someone will check mptcp and not decrypted > or vice versa when adding new code. > > This implicitly adds a decrypted check early in tcp_collapse(). > AFAIU this will very slightly increase our ability to collapse > packets under memory pressure, not a real bug. Good idea! Thank you for this refactoring, and for having cc'd MPTCP ML: Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Cheers, Matt
Jakub Kicinski wrote: > tcp_skb_can_collapse() checks for conditions which don't make > sense on input. Because of this we ended up sprinkling a few > pairs of mptcp_skb_can_collapse() and skb_cmp_decrypted() calls > on the input path. Group them in a new helper. This should make > it less likely that someone will check mptcp and not decrypted > or vice versa when adding new code. > > This implicitly adds a decrypted check early in tcp_collapse(). > AFAIU this will very slightly increase our ability to collapse > packets under memory pressure, not a real bug. > > Signed-off-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Willem de Bruijn <willemb@google.com>
diff --git a/include/net/tcp.h b/include/net/tcp.h index 32815a40dea1..32741856da01 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1071,6 +1071,13 @@ static inline bool tcp_skb_can_collapse(const struct sk_buff *to, skb_pure_zcopy_same(to, from)); } +static inline bool tcp_skb_can_collapse_rx(const struct sk_buff *to, + const struct sk_buff *from) +{ + return likely(mptcp_skb_can_collapse(to, from) && + !skb_cmp_decrypted(to, from)); +} + /* Events passed to congestion control interface */ enum tcp_ca_event { CA_EVENT_TX_START, /* first transmit when no packets in flight */ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 5aadf64e554d..212b6fd0caf7 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4813,10 +4813,7 @@ static bool tcp_try_coalesce(struct sock *sk, if (TCP_SKB_CB(from)->seq != TCP_SKB_CB(to)->end_seq) return false; - if (!mptcp_skb_can_collapse(to, from)) - return false; - - if (skb_cmp_decrypted(from, to)) + if (!tcp_skb_can_collapse_rx(to, from)) return false; if (!skb_try_coalesce(to, from, fragstolen, &delta)) @@ -5372,7 +5369,7 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root, break; } - if (n && n != tail && mptcp_skb_can_collapse(skb, n) && + if (n && n != tail && tcp_skb_can_collapse_rx(skb, n) && TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(n)->seq) { end_of_skbs = false; break; @@ -5423,11 +5420,9 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root, skb = tcp_collapse_one(sk, skb, list, root); if (!skb || skb == tail || - !mptcp_skb_can_collapse(nskb, skb) || + !tcp_skb_can_collapse_rx(nskb, skb) || (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN))) goto end; - if (skb_cmp_decrypted(skb, nskb)) - goto end; } } } diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 041c7eda9abe..228de0c95a9d 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2049,8 +2049,7 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, TCP_SKB_CB(skb)->tcp_flags) & TCPHDR_ACK) || ((TCP_SKB_CB(tail)->tcp_flags ^ TCP_SKB_CB(skb)->tcp_flags) & (TCPHDR_ECE | TCPHDR_CWR)) || - !mptcp_skb_can_collapse(tail, skb) || - skb_cmp_decrypted(tail, skb) || + !tcp_skb_can_collapse_rx(tail, skb) || thtail->doff != th->doff || memcmp(thtail + 1, th + 1, hdrlen - sizeof(*th))) goto no_coalesce;
tcp_skb_can_collapse() checks for conditions which don't make sense on input. Because of this we ended up sprinkling a few pairs of mptcp_skb_can_collapse() and skb_cmp_decrypted() calls on the input path. Group them in a new helper. This should make it less likely that someone will check mptcp and not decrypted or vice versa when adding new code. This implicitly adds a decrypted check early in tcp_collapse(). AFAIU this will very slightly increase our ability to collapse packets under memory pressure, not a real bug. Signed-off-by: Jakub Kicinski <kuba@kernel.org> --- include/net/tcp.h | 7 +++++++ net/ipv4/tcp_input.c | 11 +++-------- net/ipv4/tcp_ipv4.c | 3 +-- 3 files changed, 11 insertions(+), 10 deletions(-)