netdev - Re: [PATCH] mpls: Do not decrement alive counter for unregister events

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Message-ID: <cd885b2c-15f3-6f72-6fa9-aaabaea58ccd@cumulusnetworks.com>
Date:   Mon, 13 Mar 2017 15:11:06 -0600
From:   David Ahern <dsa@...ulusnetworks.com>
To:     Robert Shearman <rshearma@...cade.com>, netdev@...r.kernel.org
Cc:     roopa@...ulusnetworks.com
Subject: Re: [PATCH] mpls: Do not decrement alive counter for unregister
 events

On 3/13/17 5:10 AM, Robert Shearman wrote:
> Doesn't this leave the problem that if the device's link goes down and
> then the device gets deleted the alive count will be decremented twice
> for the same path?

yes. and it exposes another bug in multipath selection.

> 
> Perhaps it would be better to change the condition for decrementing the
> alive count to be "!(nh->nh_flags & (RTNH_F_LINKDOWN | RTNH_F_DEAD))"?

or maybe the logic in mpls_ifup is the way to go -- reset the alive
counter based on the sum of each nexhop's status.

I'll send more patches soon.