From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
To: David Miller <davem@davemloft.net>, razor@blackwall.org
Cc: netdev@vger.kernel.org, roopa@cumulusnetworks.com,
stephen@networkplumber.org
Subject: Re: [PATCH net-next 0/2] bridge: mdb: add support for extended attributes
Date: Thu, 18 Feb 2016 21:51:26 +0100 [thread overview]
Message-ID: <56C62ECE.6000900@cumulusnetworks.com> (raw)
In-Reply-To: <20160218.153740.101157132273397459.davem@davemloft.net>
On 02/18/2016 09:37 PM, David Miller wrote:
> From: Nikolay Aleksandrov <razor@blackwall.org>
> Date: Tue, 16 Feb 2016 12:46:52 +0100
>
>> Note that the reason we can't simply add an attribute after
>> MDBA_MDB_ENTRY_INFO is that current users (e.g. iproute2) walk over
>> the attribute list directly without checking for the attribute type.
>
> Honestly that sounds like a bug in iproute2 to me...
>
I agree, but changing this in the kernel would make older iproute2 versions
incompatible with newer kernels, possibly outputting garbage from the additional
attributes, besides we still will have to turn MDBA_MDB_ENTRY_INFO into a nested
attribute and insert the struct with a header as that's the per-mdb entry attribute
currently.
Alternatively I have a version that uses a request flag in the dump request and
sends back an alternative/"extended" version of the mdbs where every field is
a netlink attribute and is extensible, thus keeping the old format in place
and offering extended attribute support to anyone who requests it.
I just thought this version is a middle ground between the two solutions and
still doesn't break user-space while being extensible.
There're no more holes in the mdb entry struct to reuse.. :-)
Cheers,
Nik
next prev parent reply other threads:[~2016-02-18 20:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-16 11:46 [PATCH net-next 0/2] bridge: mdb: add support for extended attributes Nikolay Aleksandrov
2016-02-16 11:46 ` [PATCH net-next 1/2] bridge: mdb: reduce the indentation level in br_mdb_fill_info Nikolay Aleksandrov
2016-02-16 11:46 ` [PATCH net-next 2/2] bridge: mdb: add support for more attributes and export timer Nikolay Aleksandrov
2016-02-18 20:37 ` [PATCH net-next 0/2] bridge: mdb: add support for extended attributes David Miller
2016-02-18 20:51 ` Nikolay Aleksandrov [this message]
2016-02-19 20:26 ` David Miller
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