netdev - Re: Validation of forward

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Date:   Wed, 3 Jul 2019 00:21:05 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Roopa Prabhu <roopa@...ulusnetworks.com>,
        bridge@...ts.linux-foundation.org, netdev <netdev@...r.kernel.org>
Subject: Re: Validation of forward_delay seems wrong...

On 03/07/2019 00:19, Nikolay Aleksandrov wrote:
> On 02/07/2019 23:47, Andrew Lunn wrote:
>> Hi Nikolay
>>
>> The man page says that the bridge forward_delay is in units of
>> seconds, and should be between 2 and 30.
>>
>> I've tested on a couple of different kernel versions, and this appears
>> to be not working correctly:
>>
>> ip link set br0 type bridge forward_delay 2
>> RTNETLINK answers: Numerical result out of range
>>
>> ip link set br0 type bridge forward_delay 199
>> RTNETLINK answers: Numerical result out of range
>>
>> ip link set br0 type bridge forward_delay 200
>> # 
>>
>> ip link set br0 type bridge forward_delay 3000
>> #
>>
>> ip link set br0 type bridge forward_delay 3001
>> RTNETLINK answers: Numerical result out of range
>>
>> I've not checked what delay is actually being used here, but clearly
>> something is mixed up.
>>
>> grep HZ .config 
>> CONFIG_HZ_PERIODIC=y
>> # CONFIG_NO_HZ_IDLE is not set
>> # CONFIG_NO_HZ_FULL is not set
>> # CONFIG_NO_HZ is not set
>> CONFIG_HZ_FIXED=0
>> CONFIG_HZ_100=y
>> # CONFIG_HZ_200 is not set
>> # CONFIG_HZ_250 is not set
>> # CONFIG_HZ_300 is not set
>> # CONFIG_HZ_500 is not set
>> # CONFIG_HZ_1000 is not set
>> CONFIG_HZ=100
>>
>> Thanks
>> 	Andrew
>>
> 
> Hi Andrew,
> The man page is wrong, these have been in USER_HZ scaled clock_t format from the beginning.
> TBH a lot of the time/delay bridge config options are messed up like that.
> We've been discussing adding special _ms versions in iproute2 to make them
> more user-friendly and understandable. Will cook a patch for the man page.
> 
> Cheers,
>  Nik
> 
> 

Err, I meant it is seconds just scaled, if it wasn't clear.