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

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Date:   Tue, 28 Jul 2020 00:26:45 +0200
From:   Michal Kubecek <mkubecek@...e.cz>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Jacob Keller <jacob.e.keller@...el.com>, netdev@...r.kernel.org,
        Jamie Gloudon <jamie.gloudon@....fr>
Subject: Re: [ethtool] ethtool: fix netlink bitmasks when sent as NOMASK

On Tue, Jul 28, 2020 at 12:11:04AM +0200, Andrew Lunn wrote:
> 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.

This is a different issue, the last call to dump_link_modes() in
dump_peer_modes() should be

	ret = dump_link_modes(nlctx, attr, false, LM_CLASS_FEC,

(third parameter needs to be false, not true).

Michal

> 
> 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