From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next 0/4] net: switchdev: Avoid sleep in atomic with DSA Date: Tue, 10 Jan 2017 20:26:24 -0500 (EST) Message-ID: <20170110.202624.599513931685652148.davem@davemloft.net> References: <20170109194503.10713-1-f.fainelli@gmail.com> <20170109204849.GA28310@splinter> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: idosch@idosch.org, netdev@vger.kernel.org, vivien.didelot@savoirfairelinux.com, andrew@lunn.ch, jiri@resnulli.us To: f.fainelli@gmail.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:33790 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754822AbdAKB00 (ORCPT ); Tue, 10 Jan 2017 20:26:26 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Florian Fainelli Date: Mon, 9 Jan 2017 12:56:48 -0800 > On 01/09/2017 12:48 PM, Ido Schimmel wrote: >> Hi Florian, >> >> On Mon, Jan 09, 2017 at 11:44:59AM -0800, Florian Fainelli wrote: >>> Hi all, >>> >>> This patch series is to resolve a sleeping function called in atomic context >>> debug splat that we observe with DSA. >>> >>> Let me know what you think, I was also wondering if we should just always >>> make switchdev_port_vlan_fill() set SWITCHDEV_F_DEFER, but was afraid this >>> could cause invalid contexts to be used for rocker, mlxsw, i40e etc. >> >> Isn't this a bit of overkill? All the drivers you mention fill the VLAN >> dump from their cache and don't require sleeping. Even b53 that you >> mention in the last patch does that, but reads the PVID from the device, >> which entails taking a mutex. > > Correct. > >> >> Can't you just cache the PVID as well? I think this will solve your >> problem. Didn't look too much into the b53 code, so maybe I'm missing >> something. Seems that mv88e6xxx has a similar problem. > > I suppose we could indeed cache the PVID for b53, but for mv88e6xxx it > seems like we need to perform a bunch of VTU operations, and those > access HW registers, Andrew, Vivien, how do you want to solve that, do > we want to introduce a general VLAN cache somewhere in switchdev/DSA/driver? I would definitely prefer to see cached state used instead of this deferred operation stuff.