Validation of forward_delay seems wrong...

Validation of forward_delay seems wrong...

[Andrew Lunn]

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

Re: Validation of forward_delay seems wrong...

[Nikolay Aleksandrov]

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

Re: Validation of forward_delay seems wrong...

[Nikolay Aleksandrov]

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.

Re: Validation of forward_delay seems wrong...

[Andrew Lunn]

> 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.

Hi Nikola

Yes, that is a mess.

arch/alpha/include/asm/param.h:# define USER_HZ						1024
arch/ia64/include/asm/param.h:# define USER_HZ						HZ
include/asm-generic/param.h:# define USER_HZ						100

And ia64 does
# define HZ             CONFIG_HZ

So it seems pretty hard for user space to get this right in a generic
fashion.

	Andrew