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

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Message-Id: <20160111.002103.979291218776108297.davem@davemloft.net>
Date:	Mon, 11 Jan 2016 00:21:03 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	jiri@...nulli.us
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

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.

Applied, thanks.