netdev - Re: [PATCH] netlink: downgrade warning about leftover bytes to debug level

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Message-ID: <5385A9D1.4000102@redhat.com>
Date:	Wed, 28 May 2014 11:18:09 +0200
From:	Michal Schmidt <mschmidt@...hat.com>
To:	nicolas.dichtel@...nd.com, David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH] netlink: downgrade warning about leftover bytes to debug
 level

On 05/28/2014 09:42 AM, Nicolas Dichtel wrote:
> Le 27/05/2014 15:16, Michal Schmidt a écrit :
>> Any process is able to send netlink messages with leftover bytes, so
>> downgrade the warning message to pr_debug in order to avoid possible
>> kernel log spam.
> Yes, but that's not a normal case. I think that the level warning is good,
> there is something wrong with this kind of messages.

As an alternative we could at least guard it with net_ratelimit().

But still, the message indicates a userspace bug. It can be useful
for a developer of a netlink library, but not for many more.
I think it's odd to let unprivileged userspace spam the dmesg,
even if rate-limited. The kernel does not emit warning messages when
userspace is buggy in other ways, like calling syscalls with invalid
arguments.

Regards,
Michal
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