netdev - Re: [ethtool] ethtool: fix netlink bitmasks when sent as NOMASK

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Date:   Tue, 28 Jul 2020 00:11:04 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Jacob Keller <jacob.e.keller@...el.com>
Cc:     Michal Kubecek <mkubecek@...e.cz>, netdev@...r.kernel.org,
        Jamie Gloudon <jamie.gloudon@....fr>
Subject: Re: [ethtool] ethtool: fix netlink bitmasks when sent as NOMASK

On Mon, Jul 27, 2020 at 02:47:00PM -0700, Jacob Keller wrote:
> The ethtool netlink API can send bitsets without an associated bitmask.
> These do not get displayed properly, because the dump_link_modes, and
> bitset_get_bit to not check whether the provided bitset is a NOMASK
> bitset. This results in the inability to display peer advertised link
> modes.
> 
> The dump_link_modes and bitset_get_bit functions are designed so they
> can print either the values or the mask. For a nomask bitmap, this
> doesn't make sense. There is no mask.
> 
> Modify dump_link_modes to check ETHTOOL_A_BITSET_NOMASK. For compact
> bitmaps, always check and print the ETHTOOL_A_BITSET_VALUE bits,
> regardless of the request to display the mask or the value. For full
> size bitmaps, the set of provided bits indicates the valid values,
> without using ETHTOOL_A_BITSET_VALUE fields. Thus, do not skip printing
> bits without this attribute if nomask is set. This essentially means
> that dump_link_modes will treat a NOMASK bitset as having a mask
> equivalent to all of its set bits.
> 
> For bitset_get_bit, also check for ETHTOOL_A_BITSET_NOMASK. For compact
> bitmaps, always use ETHTOOL_A_BITSET_BIT_VALUE as in dump_link_modes.
> For full bitmaps, if nomask is set, then always return true of the bit
> is in the set, rather than only if it provides an
> ETHTOOL_A_BITSET_BIT_VALUE. This will then correctly report the set
> bits.
> 
> This fixes display of link partner advertised fields when using the
> netlink API.

Hi Jacob

This is close

Netlink
	Link partner advertised link modes:  10baseT/Half 10baseT/Full
	                                     100baseT/Half 100baseT/Full
	                                     1000baseT/Full
	Link partner advertised pause frame use: No
	Link partner advertised auto-negotiation: Yes
	Link partner advertised FEC modes: No

IOCTL
	Link partner advertised link modes:  10baseT/Half 10baseT/Full 
	                                     100baseT/Half 100baseT/Full 
	                                     1000baseT/Full 
	Link partner advertised pause frame use: No
	Link partner advertised auto-negotiation: Yes
	Link partner advertised FEC modes: Not reported

So just the FEC modes differ.

However, i don't think this was part of the original issue, so:

Tested-by: Andrew Lunn <andrew@...n.ch>

It would be nice to get the FEC modes fixed.

    Andrew