netdev - Re: [PATCH] macvlan: Support interface operstate properly

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Message-ID: <53A6C2CA-9C49-4F85-97F6-DD60276AFCC2@akamai.com>
Date:	Wed, 6 Apr 2016 21:26:33 +0000
From:	"Banerjee, Debabrata" <dbanerje@...mai.com>
To:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
	Patrick McHardy <kaber@...sh.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] macvlan: Support interface operstate properly

On 4/6/16, 5:03 PM, "Nikolay Aleksandrov" <nikolay@...ulusnetworks.com> wrote:

>On 04/06/2016 10:30 PM, Debabrata Banerjee wrote:
>> Set appropriate macvlan interface status based on lower device and our
>> status. Can be up, down, or lowerlayerdown.
>> 
>> Signed-off-by: Debabrata Banerjee <dbanerje@...mai.com>
>> 
>
>May I ask what is exactly that you're fixing here ? I recently had to make macvlan's
>operstates more accurate and I haven't experienced any wrong behaviour since commit
>de7d244d0a35 ("macvlan: make operstate and carrier more accurate").

Yes I saw the other patch, it's an improvement from when I started working on this. 

>Also it's the linkwatch's job to take care for the proper operstate, we can use
>netif_stacked_transfer_operstate to help it, but I don't think directly setting
>operstate is a good idea.

This patch was modeled after __hsr_set_operstate(). But I agree there's probably
better ways to do it. I'm not sure why netif_stacked_transfer_operstate() doesn't do
it itself, although in the case of a layered device, my patch actually uses the other
possible state, which is lowerlayerdown. Without the patch operstate goes directly to
down.

>
>One more thing - you cannot use netdev_state_change() under the write_lock as it
>may sleep.

You're right, I can resubmit moving the call out of the critical section, if the patch
will be taken.