From: David Miller <davem@davemloft.net>
To: olteanv@gmail.com
Cc: kuba@kernel.org, andrew@lunn.ch, vivien.didelot@gmail.com,
f.fainelli@gmail.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, bridge@lists.linux-foundation.org,
roopa@nvidia.com, nikolay@nvidia.com, jiri@resnulli.us,
idosch@idosch.org, claudiu.manoil@nxp.com,
alexandre.belloni@bootlin.com, UNGLinuxDriver@microchip.com,
vkochan@marvell.com, tchornyi@marvell.com,
grygorii.strashko@ti.com, ioana.ciornei@nxp.com,
ivecera@redhat.com, linux-omap@vger.kernel.org
Subject: Re: [PATCH v3 net-next 07/11] net: prep switchdev drivers for concurrent SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS
Date: Wed, 10 Feb 2021 15:34:06 -0800 (PST) [thread overview]
Message-ID: <20210210.153406.1774734837784815987.davem@davemloft.net> (raw)
In-Reply-To: <20210210091445.741269-8-olteanv@gmail.com>
From: Vladimir Oltean <olteanv@gmail.com>
Date: Wed, 10 Feb 2021 11:14:41 +0200
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
>
> Because the bridge will start offloading SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS
> while not serialized by any lock such as the br->lock spinlock, existing
> drivers that treat that attribute and cache the brport flags might no
> longer work correctly.
>
> The issue is that the brport flags are a single unsigned long bitmask,
> and the bridge only guarantees the validity of the changed bits, not the
> full state. So when offloading two concurrent switchdev attributes, such
> as one for BR_LEARNING and another for BR_FLOOD, it might happen that
> the flags having BR_FLOOD are written into the cached value, and this in
> turn disables the BR_LEARNING bit which was set previously.
>
> We can fix this across the board by keeping individual boolean variables
> for each brport flag. Note that mlxsw and prestera were setting the
> BR_LEARNING_SYNC flag too, but that appears to be just dead code, so I
> removed it.
>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
This needs updating because, as discussed, there is no race.
next prev parent reply other threads:[~2021-02-10 23:35 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 9:14 [PATCH v3 net-next 00/11] Cleanup in brport flags switchdev offload for DSA Vladimir Oltean
2021-02-10 9:14 ` [PATCH v3 net-next 01/11] net: switchdev: propagate extack to port attributes Vladimir Oltean
2021-02-11 4:12 ` Florian Fainelli
2021-02-10 9:14 ` [PATCH v3 net-next 02/11] net: bridge: offload all port flags at once in br_setport Vladimir Oltean
2021-02-10 9:14 ` [PATCH v3 net-next 03/11] net: bridge: don't print in br_switchdev_set_port_flag Vladimir Oltean
2021-02-10 9:14 ` [PATCH v3 net-next 04/11] net: dsa: configure proper brport flags when ports leave the bridge Vladimir Oltean
2021-02-11 4:16 ` Florian Fainelli
2021-02-10 9:14 ` [PATCH v3 net-next 05/11] net: squash switchdev attributes PRE_BRIDGE_FLAGS and BRIDGE_FLAGS Vladimir Oltean
2021-02-10 9:14 ` [PATCH v3 net-next 06/11] net: dsa: kill .port_egress_floods overengineering Vladimir Oltean
2021-02-11 4:18 ` Florian Fainelli
2021-02-10 9:14 ` [PATCH v3 net-next 07/11] net: prep switchdev drivers for concurrent SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS Vladimir Oltean
2021-02-10 10:12 ` Ido Schimmel
2021-02-10 10:23 ` Vladimir Oltean
2021-02-10 23:34 ` David Miller [this message]
2021-02-10 9:14 ` [PATCH v3 net-next 08/11] net: bridge: put SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS on the blocking call chain Vladimir Oltean
2021-02-10 10:14 ` Nikolay Aleksandrov
2021-02-10 9:14 ` [PATCH v3 net-next 09/11] net: mscc: ocelot: use separate flooding PGID for broadcast Vladimir Oltean
2021-02-11 4:19 ` Florian Fainelli
2021-02-10 9:14 ` [PATCH v3 net-next 10/11] net: mscc: ocelot: offload bridge port flags to device Vladimir Oltean
2021-02-11 4:20 ` Florian Fainelli
2021-02-10 9:14 ` [PATCH v3 net-next 11/11] net: dsa: sja1105: " Vladimir Oltean
2021-02-10 10:31 ` [PATCH v3 net-next 00/11] Cleanup in brport flags switchdev offload for DSA Nikolay Aleksandrov
2021-02-10 10:45 ` Vladimir Oltean
2021-02-10 10:52 ` Nikolay Aleksandrov
2021-02-10 11:01 ` Vladimir Oltean
2021-02-10 11:05 ` Nikolay Aleksandrov
2021-02-10 12:01 ` Vladimir Oltean
2021-02-10 12:10 ` Nikolay Aleksandrov
2021-02-10 12:21 ` Ido Schimmel
2021-02-10 12:29 ` Vladimir Oltean
2021-02-10 12:38 ` Ido Schimmel
2021-02-10 12:55 ` Vladimir Oltean
2021-02-10 12:59 ` Ido Schimmel
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