netdev - Re: [PATCH net-next v2] ibmvnic: Bail from ibmvnic

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Message-Id: <503418ff-323d-8eda-16c4-73c9918b38e7@linux.vnet.ibm.com>
Date:   Mon, 12 Mar 2018 15:12:18 -0500
From:   John Allen <jallen@...ux.vnet.ibm.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org,
        Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>
Subject: Re: [PATCH net-next v2] ibmvnic: Bail from ibmvnic_open if driver is
 already open

On 03/12/2018 03:10 PM, Andrew Lunn wrote:
>> The problem here is that our routine to change the mtu does a full reset on
>> the driver meaning that in the process we go from effectively "open" to
>> "closed" to "open" again.
>>
>> Consider the scenario where we change the mtu by running "ifdown <interface>",
>> editing the ifcfg file with the new mtu, and finally running "ifup <interface".
>> In this case, we call ibmvnic_close from the ifdown and as a result of the ifup,
>> we do the reset for the mtu change (which puts us back in the "open" state) and
>> call ibmvnic_open. After the reset, we are already in the "open" state and the
>> following call to open is redundant.
> 
> Hi John
> 
> So you are saying "ip link set mtu 4242 eth1" on a down interface will
> put it up. That i would say is broken. You should be fixing this,
> rather than papering over the cracks.

That's a good point. I'll work on a fix to address that.

-John

> 
>       Andrew
> 
>