kernel/net/dccp/timer.c, branch linux-rolling-stable

net: Retire DCCP socket.

2025-04-12T01:58:10Z

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

2025-03-25T17:34:33Z

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

tcp/dccp: remove icsk->icsk_timeout

2025-03-25T17:34:33Z

icsk->icsk_timeout can be replaced by icsk->icsk_retransmit_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/20250324203607.703850-2-edumazet@google.com Signed-off-by: Jakub Kicinski

tcp: record last received ipv6 flowlabel

2023-10-10T08:02:59Z

In order to better estimate whether a data packet has been retransmitted or is the result of a TLP, we save the last received ipv6 flowlabel. To make space for this field we resize the "ato" field in inet_connection_sock as the current value of TCP_DELACK_MAX can be fully contained in 8 bits and add a compile_time_assert ensuring this field is the required size. v2: addressed kernel bot feedback about dccp_delack_timer() v3: addressed build error introduced by commit bbf80d713fe7 ("tcp: derive delack_max from rto_min") Signed-off-by: David Morley Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Tested-by: David Morley Reviewed-by: Eric Dumazet Signed-off-by: Paolo Abeni

dccp: annotate lockless accesses to sk->sk_err_soft

2023-03-17T08:25:05Z

This field can be read/written without lock synchronization. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: sock: introduce sk_error_report

2021-06-29T18:28:21Z

This patch introduces a function wrapper to call the sk_error_report callback. That will prepare to add additional handling whenever sk_error_report is called, for example to trace socket errors. Signed-off-by: Alexander Aring Signed-off-by: David S. Miller

net: dccp: convert tasklets to use new tasklet_setup() API

2020-11-07T18:40:56Z

In preparation for unconditionally passing the struct tasklet_struct pointer to all tasklet callbacks, switch to using the new tasklet_setup() and from_tasklet() to pass the tasklet pointer explicitly. Signed-off-by: Romain Perier Signed-off-by: Allen Pais Signed-off-by: Jakub Kicinski

inet: remove icsk_ack.blocked

2020-09-30T21:21:30Z

TCP has been using it to work around the possibility of tcp_delack_timer() finding the socket owned by user. After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events") we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery, so we can get rid of icsk_ack.blocked This frees space that following patch will reuse. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller

net: dccp: delete repeated words

2020-08-25T00:31:20Z

Drop duplicated words in /net/dccp/. Signed-off-by: Randy Dunlap Cc: Gerrit Renker Cc: dccp@vger.kernel.org Cc: "David S. Miller" Cc: Jakub Kicinski Signed-off-by: David S. Miller

net: dccp: kerneldoc fixes

2020-07-14T00:20:39Z

Simple fixes which require no deep knowledge of the code. Cc: Gerrit Renker Signed-off-by: Andrew Lunn Signed-off-by: David S. Miller