From: Jiri Pirko <jiri@resnulli.us>
To: Ido Schimmel <idosch@idosch.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
netdev@vger.kernel.org, davem@davemloft.net,
vivien.didelot@savoirfairelinux.com, andrew@lunn.ch
Subject: Re: [PATCH net-next 0/4] net: switchdev: Avoid sleep in atomic with DSA
Date: Tue, 10 Jan 2017 17:13:55 +0100 [thread overview]
Message-ID: <20170110161355.GE1827@nanopsycho> (raw)
In-Reply-To: <20170110160852.GA18050@splinter.mtl.com>
Tue, Jan 10, 2017 at 05:08:52PM CET, idosch@idosch.org wrote:
>On Tue, Jan 10, 2017 at 03:18:07PM +0100, Jiri Pirko wrote:
>> Tue, Jan 10, 2017 at 02:25:06PM CET, idosch@idosch.org wrote:
>> >On Tue, Jan 10, 2017 at 01:08:46PM +0100, Jiri Pirko wrote:
>> >> Mon, Jan 09, 2017 at 10:14:36PM CET, idosch@idosch.org wrote:
>> >> >On Mon, Jan 09, 2017 at 12:56:48PM -0800, Florian Fainelli wrote:
>> >> >> 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?
>> >> >
>> >> >Truth be told, I don't quite understand why switchdev infra even tries
>> >> >to dump the VLANs from the device. Like, in which situations is this
>> >> >going to be different from what the software bridge reports? Sure, you
>> >> >can set the VLAN filters with SELF and skip the software bridge, but how
>> >> >does that make sense in a model where you want to reflect the software
>> >> >datapath?
>> >>
>> >> But the vlans added by rtnl_bridge_setlink & SELF are not tracked by the
>> >> bridge and therefore driver needs to dump them. You would have to pass
>> >> some flag down to driver when adding SWITCHDEV_OBJ_ID_PORT_VLAN
>> >> indicating the need to track the vlan and dump it. Right?
>> >
>> >Right, but back to my question - what's the use case for the SELF flag
>> >in the switchdev model? Why would I configure a VLAN filter in the
>> >hardware but not in the software bridge? The whole point is reflecting
>> >the software bridge to the hardware.
>>
>> I agree. For the bridge-switchdev usecase, I don't see a reason to use
>> SELF for vlans as well. Do you suggest to simply remove this possibility?
>
>Yes. This would also solve Florian's problem.
I agree, for switchdev usecase it makes no sense to implement this. I
vote for removing that.
>
>Florian, what do you think?
next prev parent reply other threads:[~2017-01-10 16:13 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-09 19:44 [PATCH net-next 0/4] net: switchdev: Avoid sleep in atomic with DSA Florian Fainelli
2017-01-09 19:45 ` [PATCH net-next 1/4] net: switchdev: Prepare for deferred functions modifying objects Florian Fainelli
2017-01-09 19:45 ` [PATCH net-next 2/4] net: switchdev: Add object dump deferred operation Florian Fainelli
2017-01-09 19:45 ` [PATCH net-next 3/4] net: switchdev: Add switchdev_port_bridge_getlink_deferred Florian Fainelli
2017-01-09 20:11 ` Marcelo Ricardo Leitner
2017-01-09 20:13 ` Florian Fainelli
2017-01-09 20:28 ` Marcelo Ricardo Leitner
2017-01-09 20:29 ` Florian Fainelli
2017-01-10 0:25 ` kbuild test robot
2017-01-09 19:45 ` [PATCH net-next 4/4] net: dsa: Utilize switchdev_port_bridge_getlink_deferred() Florian Fainelli
2017-01-09 20:48 ` [PATCH net-next 0/4] net: switchdev: Avoid sleep in atomic with DSA Ido Schimmel
2017-01-09 20:56 ` Florian Fainelli
2017-01-09 21:14 ` Ido Schimmel
2017-01-09 21:23 ` Andrew Lunn
2017-01-09 21:29 ` Ido Schimmel
2017-01-10 12:08 ` Jiri Pirko
2017-01-10 13:25 ` Ido Schimmel
2017-01-10 14:18 ` Jiri Pirko
2017-01-10 16:08 ` Ido Schimmel
2017-01-10 16:13 ` Jiri Pirko [this message]
2017-01-11 1:42 ` Florian Fainelli
2017-01-11 14:59 ` Andrew Lunn
2017-01-09 21:19 ` Vivien Didelot
2017-01-11 1:26 ` David Miller
2017-01-09 21:05 ` Andrew Lunn
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170110161355.GE1827@nanopsycho \
--to=jiri@resnulli.us \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=f.fainelli@gmail.com \
--cc=idosch@idosch.org \
--cc=netdev@vger.kernel.org \
--cc=vivien.didelot@savoirfairelinux.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).