linux.git/net/dccp/output.c, branch master

net: Retire DCCP socket.

2025-04-12T01:58:10+00:00

DCCP was orphaned in 2021 by commit 054c4610bd05 ("MAINTAINERS: dccp:
move Gerrit Renker to CREDITS"), which noted that the last maintainer
had been inactive for five years.

In recent years, it has become a playground for syzbot, and most changes
to DCCP have been odd bug fixes triggered by syzbot. Apart from that,
the only changes have been driven by treewide or networking API updates
or adjustments related to TCP.

Thus, in 2023, we announced we would remove DCCP in 2025 via commit
b144fcaf46d4 ("dccp: Print deprecation notice.").

Since then, only one individual has contacted the netdev mailing list. [0]

There is ongoing research for Multipath DCCP. The repository is hosted
on GitHub [1], and development is not taking place through the upstream
community. While the repository is published under the GPLv2 license,
the scheduling part remains proprietary, with a LICENSE file [2] stating:

"This is not Open Source software."

The researcher mentioned a plan to address the licensing issue, upstream
the patches, and step up as a maintainer, but there has been no further
communication since then.

Maintaining DCCP for a decade without any real users has become a burden.

Therefore, it's time to remove it.

Removing DCCP will also provide significant benefits to TCP. It allows
us to freely reorganize the layout of struct inet_connection_sock, which
is currently shared with DCCP, and optimize it to reduce the number of
cachelines accessed in the TCP fast path.

Note that we keep DCCP netfilter modules as requested. [3]

Link: https://lore.kernel.org/netdev/20230710182253.81446-1-kuniyu@amazon.com/T/#u #[0]
Link: https://github.com/telekom/mp-dccp #[1]
Link: https://github.com/telekom/mp-dccp/blob/mpdccp_v03_k5.10/net/dccp/non_gpl_scheduler/LICENSE #[2]
Link: https://lore.kernel.org/netdev/Z_VQ0KlCRkqYWXa-@calendula/ #[3]
Signed-off-by: Kuniyuki Iwashima
Acked-by: Paul Moore (LSM and SELinux)
Acked-by: Casey Schaufler
Link: https://patch.msgid.link/20250410023921.11307-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski

tcp/dccp: remove icsk->icsk_ack.timeout

2025-03-25T17:34:33+00:00

icsk->icsk_ack.timeout can be replaced by icsk->csk_delack_timer.expires

This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality.

Signed-off-by: Eric Dumazet 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20250324203607.703850-3-edumazet@google.com
Signed-off-by: Jakub Kicinski

net: add sk_wake_async_rcu() helper

2024-03-29T22:03:11+00:00

While looking at UDP receive performance, I saw sk_wake_async()
was no longer inlined.

This matters at least on AMD Zen1-4 platforms (see SRSO)

This might be because rcu_read_lock() and rcu_read_unlock()
are no longer nops in recent kernels ?

Add sk_wake_async_rcu() variant, which must be called from
contexts already holding rcu lock.

As SOCK_FASYNC is deprecated in modern days, use unlikely()
to give a hint to the compiler.

sk_wake_async_rcu() is properly inlined from
__udp_enqueue_schedule_skb() and sock_def_readable().

Signed-off-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20240328144032.1864988-5-edumazet@google.com
Signed-off-by: Jakub Kicinski

dccp: fix data-race around dp->dccps_mss_cache

2023-08-05T01:27:58+00:00

dccp_sendmsg() reads dp->dccps_mss_cache before locking the socket.
Same thing in do_dccp_getsockopt().

Add READ_ONCE()/WRITE_ONCE() annotations,
and change dccp_sendmsg() to check again dccps_mss_cache
after socket is locked.

Fixes: 7c657876b63c ("[DCCP]: Initial implementation")
Reported-by: syzbot 
Signed-off-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20230803163021.2958262-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

net: dccp: Fix most of the kerneldoc warnings

2020-10-30T19:08:54+00:00

net/dccp/ccids/ccid2.c:190: warning: Function parameter or member 'hc' not described in 'ccid2_update_used_window'
net/dccp/ccids/ccid2.c:190: warning: Function parameter or member 'new_wnd' not described in 'ccid2_update_used_window'
net/dccp/ccids/ccid2.c:360: warning: Function parameter or member 'sk' not described in 'ccid2_rtt_estimator'
net/dccp/ccids/ccid3.c:112: warning: Function parameter or member 'sk' not described in 'ccid3_hc_tx_update_x'
net/dccp/ccids/ccid3.c:159: warning: Function parameter or member 'hc' not described in 'ccid3_hc_tx_update_s'
net/dccp/ccids/ccid3.c:268: warning: Function parameter or member 'sk' not described in 'ccid3_hc_tx_send_packet'
net/dccp/ccids/ccid3.c:667: warning: Function parameter or member 'sk' not described in 'ccid3_first_li'
net/dccp/ccids/ccid3.c:85: warning: Function parameter or member 'hc' not described in 'ccid3_update_send_interval'
net/dccp/ccids/lib/loss_interval.c:85: warning: Function parameter or member 'lh' not described in 'tfrc_lh_update_i_mean'
net/dccp/ccids/lib/loss_interval.c:85: warning: Function parameter or member 'skb' not described in 'tfrc_lh_update_i_mean'
net/dccp/ccids/lib/packet_history.c:392: warning: Function parameter or member 'h' not described in 'tfrc_rx_hist_sample_rtt'
net/dccp/ccids/lib/packet_history.c:392: warning: Function parameter or member 'skb' not described in 'tfrc_rx_hist_sample_rtt'
net/dccp/feat.c:1003: warning: Function parameter or member 'dreq' not described in 'dccp_feat_server_ccid_dependencies'
net/dccp/feat.c:1040: warning: Function parameter or member 'array_len' not described in 'dccp_feat_prefer'
net/dccp/feat.c:1040: warning: Function parameter or member 'array' not described in 'dccp_feat_prefer'
net/dccp/feat.c:1040: warning: Function parameter or member 'preferred_value' not described in 'dccp_feat_prefer'
net/dccp/output.c:151: warning: Function parameter or member 'dp' not described in 'dccp_determine_ccmps'
net/dccp/output.c:242: warning: Function parameter or member 'sk' not described in 'dccp_xmit_packet'
net/dccp/output.c:305: warning: Function parameter or member 'sk' not described in 'dccp_flush_write_queue'
net/dccp/output.c:305: warning: Function parameter or member 'time_budget' not described in 'dccp_flush_write_queue'
net/dccp/output.c:378: warning: Function parameter or member 'sk' not described in 'dccp_retransmit_skb'
net/dccp/qpolicy.c:88: warning: Function parameter or member '' not described in 'dccp_qpolicy_operations'
net/dccp/qpolicy.c:88: warning: Function parameter or member '{' not described in 'dccp_qpolicy_operations'
net/dccp/qpolicy.c:88: warning: Function parameter or member 'params' not described in 'dccp_qpolicy_operations'

Signed-off-by: Andrew Lunn 
Link: https://lore.kernel.org/r/20201028011412.931250-1-andrew@lunn.ch
Signed-off-by: Jakub Kicinski

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59+00:00

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

sched/headers: Prepare to move signal wakeup & sigpending methods from into

2017-03-02T07:42:32+00:00

Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

net: Generalise wq_has_sleeper helper

2015-11-30T19:47:33+00:00

The memory barrier in the helper wq_has_sleeper is needed by just
about every user of waitqueue_active.  This patch generalises it
by making it take a wait_queue_head_t directly.  The existing
helper is renamed to skwq_has_sleeper.

Signed-off-by: Herbert Xu 
Signed-off-by: David S. Miller

dccp: constify dccp_make_response() socket argument

2015-09-25T20:00:39+00:00

Like tcp_make_synack() the only time we might change the socket is
when calling sock_wmalloc(), which is using atomic operation to
update sk->sk_wmem_alloc

Also use MAX_DCCP_HEADER as both IPv4/IPv6 use this value for max_header.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller