Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 30 Jul 2021 09:46:31 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc:     netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
        Arnd Bergmann <arnd@arndb.de>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Florian Westphal <fw@strlen.de>, linux-kernel@vger.kernel.org,
        linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org,
        linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org,
        linux-arch@vger.kernel.org, Andrei Vagin <avagin@gmail.com>
Subject: Re: [PATCH v2] sock: allow reading and changing sk_userlocks with
 setsockopt
Message-ID: <20210730094631.106b8bec@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <20210730160708.6544-1-ptikhomirov@virtuozzo.com>
References: <20210730160708.6544-1-ptikhomirov@virtuozzo.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

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@virtuozzo.com>

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