From: Vladimir Oltean <olteanv@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>,
"David S. Miller" <davem@davemloft.net>
Cc: Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
bridge@lists.linux-foundation.org,
Roopa Prabhu <roopa@nvidia.com>,
Nikolay Aleksandrov <nikolay@nvidia.com>,
Jiri Pirko <jiri@resnulli.us>, Ido Schimmel <idosch@idosch.org>,
Claudiu Manoil <claudiu.manoil@nxp.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
UNGLinuxDriver@microchip.com, Vadym Kochan <vkochan@marvell.com>,
Taras Chornyi <tchornyi@marvell.com>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Ioana Ciornei <ioana.ciornei@nxp.com>,
Ivan Vecera <ivecera@redhat.com>,
linux-omap@vger.kernel.org
Subject: Re: [PATCH v2 net-next 02/11] net: bridge: offload all port flags at once in br_setport
Date: Tue, 9 Feb 2021 20:36:36 +0200 [thread overview]
Message-ID: <20210209183636.l5h4zyknk5q4kvgl@skbuf> (raw)
In-Reply-To: <20210209182724.b4funpoqh6kgoj6z@skbuf>
On Tue, Feb 09, 2021 at 08:27:24PM +0200, Vladimir Oltean wrote:
> But there's an interesting side effect of allowing
> br_switchdev_set_port_flag to run concurrently (notifier call chains use
> a rw_semaphore and only take the read side). Basically now drivers that
> cache the brport flags in their entirety are broken, because there isn't
> any guarantee that bits outside the mask are valid any longer (we can
> even enforce that by masking the flags with the mask when notifying
> them). They would need to do the same trick of updating just the masked
> part of their cached flags. Except for the fact that they would need
> some sort of spinlock too, I don't think that the basic bitwise
> operations are atomic or anything like that. I'm a bit reluctant to add
> a spinlock in prestera, rocker, mlxsw just for this purpose. What do you
> think?
My take on things is that I can change those drivers to do what ocelot
and sja1105 do, which is to just have some bool values like this:
if (flags.mask & BR_LEARNING)
ocelot_port->learn_ena = !!(flags.val & BR_LEARNING);
which eliminates concurrency to the shared unsigned long brport_flags
variable. No locking, no complications.
next prev parent reply other threads:[~2021-02-09 18:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 15:19 [PATCH v2 net-next 00/11] Cleanup in brport flags switchdev offload for DSA Vladimir Oltean
2021-02-09 15:19 ` [PATCH v2 net-next 01/11] net: switchdev: propagate extack to port attributes Vladimir Oltean
2021-02-09 18:00 ` Ido Schimmel
2021-02-09 15:19 ` [PATCH v2 net-next 02/11] net: bridge: offload all port flags at once in br_setport Vladimir Oltean
2021-02-09 18:27 ` Vladimir Oltean
2021-02-09 18:36 ` Vladimir Oltean [this message]
2021-02-09 15:19 ` [PATCH v2 net-next 03/11] net: bridge: don't print in br_switchdev_set_port_flag Vladimir Oltean
2021-02-09 17:36 ` Vladimir Oltean
2021-02-09 18:26 ` Ido Schimmel
2021-02-09 15:19 ` [PATCH v2 net-next 04/11] net: bridge: offload initial and final port flags through switchdev Vladimir Oltean
2021-02-09 18:51 ` Ido Schimmel
2021-02-09 20:20 ` Vladimir Oltean
2021-02-09 22:01 ` Ido Schimmel
2021-02-09 22:51 ` Vladimir Oltean
2021-02-10 10:59 ` Ido Schimmel
2021-02-10 23:23 ` Vladimir Oltean
2021-02-11 7:44 ` Ido Schimmel
2021-02-11 9:35 ` Vladimir Oltean
2021-02-11 22:20 ` Ido Schimmel
2021-02-09 15:19 ` [PATCH v2 net-next 05/11] net: dsa: stop setting initial and final brport flags Vladimir Oltean
2021-02-09 15:19 ` [PATCH v2 net-next 06/11] net: squash switchdev attributes PRE_BRIDGE_FLAGS and BRIDGE_FLAGS Vladimir Oltean
2021-02-09 15:19 ` [PATCH v2 net-next 07/11] net: dsa: kill .port_egress_floods overengineering Vladimir Oltean
2021-02-09 20:37 ` Vladimir Oltean
2021-02-09 21:29 ` Florian Fainelli
2021-02-09 15:19 ` [PATCH v2 net-next 08/11] net: bridge: put SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS on the blocking call chain Vladimir Oltean
2021-02-09 15:19 ` [PATCH v2 net-next 09/11] net: mscc: ocelot: use separate flooding PGID for broadcast Vladimir Oltean
2021-02-09 15:19 ` [PATCH v2 net-next 10/11] net: mscc: ocelot: offload bridge port flags to device Vladimir Oltean
2021-02-09 15:19 ` [PATCH v2 net-next 11/11] net: dsa: sja1105: " Vladimir Oltean
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