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Subject: Re: [PATCH net-next v5 09/22] ethtool: implement EVENT notifications
To:     Michal Kubecek <mkubecek@suse.cz>, Jiri Pirko <jiri@resnulli.us>
Cc:     David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Andrew Lunn <andrew@lunn.ch>,
        John Linville <linville@tuxdriver.com>,
        Stephen Hemminger <stephen@networkplumber.org>,
        linux-kernel@vger.kernel.org
References: <cover.1553532199.git.mkubecek@suse.cz>
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 <20190327130428.GB14297@nanopsycho> <20190327141443.GS26076@unicorn.suse.cz>
From:   Florian Fainelli <f.fainelli@gmail.com>
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Message-ID: <a3d94fdf-964a-5a2c-3d96-74a0323af37e@gmail.com>
Date:   Wed, 27 Mar 2019 19:14:43 -0700
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On 3/27/2019 7:14 AM, Michal Kubecek wrote:
> On Wed, Mar 27, 2019 at 02:04:28PM +0100, Jiri Pirko wrote:
>> Mon, Mar 25, 2019 at 06:08:21PM CET, mkubecek@suse.cz wrote:
>>> Three types of netlink notifications are introduced:
>>>
>>>  - ETHA_EVENT_NEWDEV to notify about newly registered network devices
>>>  - ETHA_EVENT_DELDEV to notify about unregistered network devices
>>>  - ETHA_EVENT_RENAMEDEV to notify about renamed network device
>>>
>>> The notifications are triggered by NETDEV_REGISTER, NETDEV_UNREGISTER and
>>> NETDEV_CHANGENAME notifiers.
>>>
>>> These notifications are intended for applications and daemons monitoring
>>> ethtool events to allow updating the list of existing devices without
>>> having to open another socket for rtnetlink.
>>
>> Wait. You duplicate events that are already going out through RTNETLINK.
>> App should open RTNETLINK in order to get those. Other apps are doing
>> that too. I don't think that duplications like this are desirable :/
> 
> Is there a way to filter or at least recognize these events when using
> rtnetlink? I couldn't find any. The only way seems to be getting every
> RTM_NEWLINK message (there can be quite a lot of those), always perform
> the lookup in my device list and recognize what happened - only to
> almost always find that nothing interesting. It is possible, sure, but
> I would really like to avoid it.

I am afraid you are right about this, would adding a filtering
capability specifically for this in rtnetlink be a better route?
-- 
Florian