netdev - Re: [PATCH net-next v3 1/2] RDS: TCP: Add sysctl tunables for sndbuf/rcvbuf on rds-tcp socket

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Message-ID: <56E942F0.90201@stressinduktion.org>
Date:	Wed, 16 Mar 2016 12:26:40 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Sowmini Varadhan <sowmini.varadhan@...cle.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	santosh.shilimkar@...cle.com, eric.dumazet@...il.com
Subject: Re: [PATCH net-next v3 1/2] RDS: TCP: Add sysctl tunables for
 sndbuf/rcvbuf on rds-tcp socket

On 16.03.2016 12:10, Sowmini Varadhan wrote:
> On (03/16/16 11:29), Hannes Frederic Sowa wrote:
>> Normally we kmemdup a table per netns and update its data pointer,
>> so we can reuse the proc_doint_minmax functions.
>
> I remembered one more thing.. in this particular case, I need to
> have my one ->proc_handler, because I need to rds_tcp_sysctl_reset()
> existing connections to make them use the new tunable.

My hope was actually that by using the ->data pointer in netns you don't 
need to provide the two functions, just simply use something like the 
following for both cases.

static int rds_skbuf_handler(...) {
	int err;

	err = proc_dointvec(...);
	if (err)
		return err;

	if (write)
		rds_tcp_sysctl_reset(...);

	return err;
}

If you use proc_dointvec_min(max) you can already sanitize the input 
values even more.

Do I understand it correctly that all connections of a namespace will be 
dropped if you modify those sysctls?

Thanks,
Hannes