netdev - Re: [patch net] mlxsw: spectrum: Add FDB lock to prevent session interleaving

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Message-ID: <20160111084135.GA2246@nanopsycho.orion>
Date:	Mon, 11 Jan 2016 09:41:36 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, idosch@...lanox.com, eladr@...lanox.com,
	yotamg@...lanox.com, ogerlitz@...lanox.com
Subject: Re: [patch net] mlxsw: spectrum: Add FDB lock to prevent session
 interleaving

Mon, Jan 11, 2016 at 06:21:03AM CET, davem@...emloft.net wrote:
>From: Jiri Pirko <jiri@...nulli.us>
>Date: Sun, 10 Jan 2016 09:32:16 +0100
>
>> From: Ido Schimmel <idosch@...lanox.com>
>> 
>> Dumping the FDB (invoked with a process context) or handling FDB
>> notifications (polled periodicly in delayed work) might each entail
>> multiple EMAD transcations due to the number of entries.
>> 
>> While we only allow one EMAD transaction at a time, there is nothing
>> stopping the dump and notification processing sessions from
>> interleaving. However, this is forbidden by the hardware, so we need to
>> make sure only one of these sessions can run at a time.
>> 
>> Solve this by adding a mutex ('fdb_lock'), as both kernel threads can
>> sleep while waiting for the response EMAD.
>> 
>> Fixes: 56ade8fe3f ("mlxsw: spectrum: Add initial support for Spectrum ASIC")
>> Signed-off-by: Ido Schimmel <idosch@...lanox.com>
>> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>
>Jiri, I noticed you submitted both a net and a net-next variant of
>this same fix.  Please don't ever do that.
>
>it's easiest if I just apply the 'net' variant and handle the merge
>issues when I pull 'net' into 'net-next', so that how I'm going to
>handle this change.

Okay. I just wanted to help since the net-next patch differs. Thanks!