netdev - Re: [PATCH v2] net/bpfilter: fix dprintf usage for /dev/kmsg

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Date:   Mon, 30 Mar 2020 10:13:13 -0300
From:   Bruno Meneguele <bmeneg@...hat.com>
To:     Martin Zaharinov <micron10@...il.com>
Cc:     netdev@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>
Subject: Re: [PATCH v2] net/bpfilter: fix dprintf usage for /dev/kmsg

On Mon, Mar 30, 2020 at 03:48:12PM +0300, Martin Zaharinov wrote:
> Hi Bruno
> i see after release kernel 5.6.0 with your latest patch have strange
> messages please check:
> 
> [   31.025483] bpfilter: Loaded bpfilter_umh pid 2689
> [   31.025533] Started bpfilter
> [   31.042586] testing the buffer
> [   31.050822] testing the buffer
> [   31.059304] testing the buffer
> [   31.067747] testing the buffer
> [   31.148789] testing the buffer
> [   31.156130] testing the buffer
> [   31.164012] testing the buffer
> [   31.170685] testing the buffer
> [   31.176886] testing the buffer
> 
> when drop bpfilter module stop enter new messages in kmsg.
> 

Hi Martin,

these aren't really "strange messages", but the correct ones. They
started to appear now because before my patch the log wasn't working at
all. I'm not really aware what is the logic behind the bpfilter_umh
module, but AFAIK each iptable rule sent from kernel side to UMH
userspace code will generate one "testing the buffer" message.

I think we can silence it by limiting it to print only once, but I would
need to check with Alexei Starovoitov <ast@...nel.org> if it would be
fine (CC'ing here).

Thanks for the heads up :).

-- 
bmeneg 
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