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From: Vladimir Oltean <olteanv@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>, Florian Fainelli <f.fainelli@gmail.com>
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>,
	Saravana Kannan <saravanak@google.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	p.rosenberger@kunbus.com, woojung.huh@microchip.com,
	UNGLinuxDriver@microchip.com, vivien.didelot@gmail.com,
	davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] Fix for KSZ DSA switch shutdown
Date: Sat, 11 Sep 2021 14:44:30 +0300	[thread overview]
Message-ID: <20210911114430.rvlee7cyes2xhzws@skbuf> (raw)
In-Reply-To: <20210910145852.4te2zjkchnajb3qw@skbuf>

On Fri, Sep 10, 2021 at 05:58:52PM +0300, Vladimir Oltean wrote:
> On Fri, Sep 10, 2021 at 01:51:56PM +0200, Andrew Lunn wrote:
> > > It does not really scale but we also don't have that many DSA masters to
> > > support, I believe I can name them all: bcmgenet, stmmac, bcmsysport, enetc,
> > > mv643xx_eth, cpsw, macb.
> > 
> > fec, mvneta, mvpp2, i210/igb.
> 
> I can probably double that list only with Freescale/NXP Ethernet
> drivers, some of which are not even submitted to mainline. To name some
> mainline drivers: gianfar, dpaa-eth, dpaa2-eth, dpaa2-switch, ucc_geth.
> Also consider that DSA/switchdev drivers can also be DSA masters of
> their own, we have boards doing that too.
> 
> Anyway, I've decided to at least try and accept the fact that DSA
> masters will unregister their net_device on shutdown, and attempt to do
> something sane for all DSA switches in that case.
> 
> Attached are two patches (they are fairly big so I won't paste them
> inline, and I would like initial feedback before posting them to the
> list).
> 
> As mentioned in those patches, the shutdown ordering guarantee is still
> very important, I still have no clue what goes on there, what we need to
> do, etc.

So to answer my own question, there is a comment above device_link_add:

 * A side effect of the link creation is re-ordering of dpm_list and the
 * devices_kset list by moving the consumer device and all devices depending
 * on it to the ends of these lists (that does not happen to devices that have
 * not been registered when this function is called).

so the fact that DSA uses device_link_add towards its master is not
exactly for nothing. device_shutdown() walks devices_kset from the back,
so this is our guarantee that DSA's shutdown happens before the master's
shutdown.

So these patches should be okay. Any other comments? If not, I will
formally submit them tomorrow towards the net tree.

  reply	other threads:[~2021-09-11 11:44 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-09  9:53 [PATCH 0/3] Fix for KSZ DSA switch shutdown Lino Sanfilippo
2021-09-09  9:53 ` [PATCH 1/3] net: dsa: introduce function dsa_tree_shutdown() Lino Sanfilippo
2021-09-09  9:53 ` [PATCH 2/3] net: dsa: microchip: provide the function ksz_switch_shutdown() Lino Sanfilippo
2021-09-09  9:53 ` [PATCH 3/3] net: dsa: microchip: tear down DSA tree at system shutdown Lino Sanfilippo
2021-09-09 10:14 ` [PATCH 0/3] Fix for KSZ DSA switch shutdown Vladimir Oltean
2021-09-09 11:08   ` Lino Sanfilippo
2021-09-09 11:42     ` Vladimir Oltean
2021-09-09 12:56       ` Vladimir Oltean
2021-09-09 13:19         ` Aw: " Lino Sanfilippo
2021-09-09 14:29           ` Lino Sanfilippo
2021-09-09 15:17             ` Andrew Lunn
2021-09-09 16:41               ` Lino Sanfilippo
2021-09-09 15:11           ` Andrew Lunn
2021-09-09 16:46             ` Lino Sanfilippo
2021-09-09 17:55               ` Andrew Lunn
2021-09-09 15:47           ` Vladimir Oltean
2021-09-09 16:00             ` Florian Fainelli
2021-09-10  1:32               ` Saravana Kannan
2021-09-09 16:37             ` Lino Sanfilippo
2021-09-09 16:44               ` Florian Fainelli
2021-09-09 17:07                 ` Lino Sanfilippo
2021-09-09 22:54                   ` Vladimir Oltean
2021-09-09 23:23                     ` Vladimir Oltean
2021-09-10  1:08                       ` Vladimir Oltean
2021-09-10  2:15                     ` Florian Fainelli
2021-09-10 11:51                       ` Andrew Lunn
2021-09-10 14:58                         ` Vladimir Oltean
2021-09-11 11:44                           ` Vladimir Oltean [this message]
2021-09-12 20:19                           ` Lino Sanfilippo
2021-09-12 20:29                             ` Vladimir Oltean
2021-09-13 10:32                               ` Aw: " Lino Sanfilippo
2021-09-13 10:44                                 ` Vladimir Oltean
2021-09-13 11:01                                   ` Aw: " Lino Sanfilippo
2021-09-14 18:48                                     ` Vladimir Oltean
2021-09-15  5:42                                       ` Lino Sanfilippo
2021-09-18 19:37                                         ` Lino Sanfilippo
2021-09-18 22:04                                           ` Vladimir Oltean
2021-09-19  0:29                                             ` Vladimir Oltean
2021-09-09 12:40 ` Andrew Lunn

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