netdev - Re: [PATCH next 0/5] link-status fixes for mii-monitoring

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Message-Id: <20170327.211210.674299237092414810.davem@davemloft.net>
Date:   Mon, 27 Mar 2017 21:12:10 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     mahesh@...dewar.net
Cc:     j.vosburgh@...il.com, andy@...yhouse.net, vfalico@...il.com,
        nikolay@...hat.com, edumazet@...gle.com, netdev@...r.kernel.org,
        maheshb@...gle.com
Subject: Re: [PATCH next 0/5] link-status fixes for mii-monitoring

From: Mahesh Bandewar <mahesh@...dewar.net>
Date: Mon, 27 Mar 2017 11:37:24 -0700

> From: Mahesh Bandewar <maheshb@...gle.com>
> 
> The mii monitoring is divided into two phases - inspect and commit. The
> inspect phase technically should not make any changes to the state and
> defer it to the commit phase. However detected link state inconsistencies
> on several machines and discovered that it's the result of some
> inconsistent update to link states and assumption that you *always* get
> rtnl-mutex. In reality when trylock() fails to acquire rtnl-mutex, the
> commit phase is postponed until next mii-mon run. At the next round
> because of the state change performed in the previous inspect-run, this
> round does not detect any changes and would skip calling commit phase.
> This would result in an inconsistent state until next link event happens
> (if it ever happens).
> 
> During the the commit phase, it's always assumed that speed and duplex
> fetch is always successful, but that's always not the case. However the
> slave state is marked UP irrespective of speed / duplex fetch operation.
> If the speed / duplex fetch operation results in insane values for either
> of these two fields, then keeping internal link state UP is not going to
> provide fruitful results either.
> 
> Please see into individual patches for more details.

Looks good, series applied, thanks.