Re: [PATCH v2] sock: allow reading and changing sk_userlocks with setsockopt

[Jakub Kicinski]

On Fri, 30 Jul 2021 19:07:08 +0300 Pavel Tikhomirov wrote:
> SOCK_SNDBUF_LOCK and SOCK_RCVBUF_LOCK flags disable automatic socket
> buffers adjustment done by kernel (see tcp_fixup_rcvbuf() and
> tcp_sndbuf_expand()). If we've just created a new socket this adjustment
> is enabled on it, but if one changes the socket buffer size by
> setsockopt(SO_{SND,RCV}BUF*) it becomes disabled.
> 
> CRIU needs to call setsockopt(SO_{SND,RCV}BUF*) on each socket on
> restore as it first needs to increase buffer sizes for packet queues
> restore and second it needs to restore back original buffer sizes. So
> after CRIU restore all sockets become non-auto-adjustable, which can
> decrease network performance of restored applications significantly.
> 
> CRIU need to be able to restore sockets with enabled/disabled adjustment
> to the same state it was before dump, so let's add special setsockopt
> for it.
> 
> Signed-off-by: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx>

The patchwork bot is struggling to ingest this, please double check it
applies cleanly to net-next.