Re: [net-next-2.6 PATCH] ethtool: update get_rx_ntuple to correctly interpret string count

On Tue, 2011-01-04 at 17:06 -0800, Alexander Duyck wrote:

On 1/4/2011 4:01 PM, Ben Hutchings wrote:

quoted

On Tue, 2011-01-04 at 15:29 -0800, Alexander Duyck wrote:

quoted

Currently any strings returned via the get_rx_ntuple call will just be
dropped because the num_strings will be zero.  In order to correct this I
am updating things so that the return value of get_rx_ntuple is the number
of strings that were written, or a negative value if there was an error.

[...]

Nothing implements ethtool_ops::get_rx_ntuple, anyway.

The fallback implementation is totally bogus, too.  Maximum of 1024
filters?  Erm, sfc can handle more than that.  And doing complex string
formatting in the kernel, even though all the parsing is in ethtool?

Please, let's write off ETHTOOL_GRXNTUPLE as a failed experiment and
replace it with a command that behaves more like ETHTOOL_GRXCLSRLALL.

Ben.

In order to address several different issues in the perfect filters 
provided by 82599 I found it necessary to implement get_rx_ntuple so 
that the driver could maintain the filter list inside of the driver 
instead of having it maintained by the stack.  In doing so though I 
found the bug.

I agree the fallback implementation has a limitation on the number and 
format of filters it supports.  However declaring the function a "failed 
experiment" and just dropping it isn't exactly constructive since we 
have customers that are making use of the feature.

[...]

We can at least drop that fallback implementation since it apparently
doesn't work properly for either of the drivers that currently use it.

In the medium term, I do want to replace it with a binary interface and
move that formatting to ethtool.  ETHTOOL_GRXNTUPLE could be kept around
for a while for ixgbe only, while your customers have a chance to get
the updated ethtool.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
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