| Message ID | 7f941e06e6434902ea4a0a572392f65cd2745447.1625053058.git.pabeni@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 71158bb1f2d2da61385c58fc1114e1a1c19984ba |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] tcp: consistently disable header prediction for mptcp | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | success | CCed 7 of 7 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 1091 this patch: 1091 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 10 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 1093 this patch: 1093 |
| netdev/header_inline | success | Link |
On 6/30/21 1:42 PM, Paolo Abeni wrote: > The MPTCP receive path is hooked only into the TCP slow-path. > The DSS presence allows plain MPTCP traffic to hit that > consistently. > > Since commit e1ff9e82e2ea ("net: mptcp: improve fallback to TCP"), > when an MPTCP socket falls back to TCP, it can hit the TCP receive > fast-path, and delay or stop triggering the event notification. > > Address the issue explicitly disabling the header prediction > for MPTCP sockets. > > Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/200 > Fixes: e1ff9e82e2ea ("net: mptcp: improve fallback to TCP") > Signed-off-by: Paolo Abeni <pabeni@redhat.com> > --- SGTM, thanks. Reviewed-by: Eric Dumazet <edumazet@google.com>
Hello: This patch was applied to netdev/net.git (refs/heads/master): On Wed, 30 Jun 2021 13:42:13 +0200 you wrote: > The MPTCP receive path is hooked only into the TCP slow-path. > The DSS presence allows plain MPTCP traffic to hit that > consistently. > > Since commit e1ff9e82e2ea ("net: mptcp: improve fallback to TCP"), > when an MPTCP socket falls back to TCP, it can hit the TCP receive > fast-path, and delay or stop triggering the event notification. > > [...] Here is the summary with links: - [net] tcp: consistently disable header prediction for mptcp https://git.kernel.org/netdev/net/c/71158bb1f2d2 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/include/net/tcp.h b/include/net/tcp.h index d05193cb0d99..b42b3e6731ed 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -682,6 +682,10 @@ static inline u32 __tcp_set_rto(const struct tcp_sock *tp) static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) { + /* mptcp hooks are only on the slow path */ + if (sk_is_mptcp((struct sock *)tp)) + return; + tp->pred_flags = htonl((tp->tcp_header_len << 26) | ntohl(TCP_FLAG_ACK) | snd_wnd);
The MPTCP receive path is hooked only into the TCP slow-path. The DSS presence allows plain MPTCP traffic to hit that consistently. Since commit e1ff9e82e2ea ("net: mptcp: improve fallback to TCP"), when an MPTCP socket falls back to TCP, it can hit the TCP receive fast-path, and delay or stop triggering the event notification. Address the issue explicitly disabling the header prediction for MPTCP sockets. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/200 Fixes: e1ff9e82e2ea ("net: mptcp: improve fallback to TCP") Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- Notes: - I'm unable to disable header prediction consistently for MPTCP sockets touching only MPTCP code - possible alternatives could be: - hook MPTCP in the TCP fastpath, too - try to pull again commit 45f119bf936b ("tcp: remove header prediction") avoiding the regression noded in 31770e34e43d ("tcp: Revert "tcp: remove header prediction"") I choose this option as the hopefully less invasive one. --- include/net/tcp.h | 4 ++++ 1 file changed, 4 insertions(+)