Merge branch 'tcp-add-fast-path-in-timer-handlers'

Eric Dumazet says:

====================
tcp: add fast path in timer handlers

As mentioned in Netconf 2024:

TCP retransmit and delack timers are not stopped from
inet_csk_clear_xmit_timer() because we do not define
INET_CSK_CLEAR_TIMERS.

Enabling INET_CSK_CLEAR_TIMERS leads to lower performance,
mainly because del_timer() and mod_timer() happen from
different cpus quite often.

What we can do instead is to add fast paths to tcp_write_timer()
and tcp_delack_timer() to avoid socket spinlock acquisition.
====================

Link: https://patch.msgid.link/20241002173042.917928-1-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>