From: Andrew Lunn <andrew@lunn.ch>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>,
Vivien Didelot <vivien.didelot@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org
Subject: Re: [PATCH net] net: dsa: fix unintended change of bridge interface STP state
Date: Wed, 20 Feb 2019 18:27:15 +0100 [thread overview]
Message-ID: <20190220172715.GL13075@lunn.ch> (raw)
In-Reply-To: <b7f73796-8545-c953-d71b-c0b0adb85965@gmail.com>
On Wed, Feb 20, 2019 at 09:22:30AM -0800, Florian Fainelli wrote:
> On 2/20/19 2:32 AM, Russell King wrote:
> > When a DSA port is added to a bridge and brought up, the resulting STP
> > state programmed into the hardware depends on the order that these
> > operations are performed. However, the Linux bridge code believes that
> > the port is in disabled mode.
> >
> > If the DSA port is first added to a bridge and then brought up, it will
> > be in blocking mode. If it is brought up and then added to the bridge,
> > it will be in disabled mode.
> >
> > This difference is caused by DSA always setting the STP mode in
> > dsa_port_enable() whether or not this port is part of a bridge. Since
> > bridge always sets the STP state when the port is added, brought up or
> > taken down, it is unnecessary for us to manipulate the STP state.
> >
> > Apparently, this code was copied from Rocker, and the very next day a
> > similar fix for Rocker was merged but was not propagated to DSA. See
> > e47172ab7e41 ("rocker: put port in FORWADING state after leaving bridge")
> >
> > Fixes: b73adef67765 ("net: dsa: integrate with SWITCHDEV for HW bridging")
> > Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
>
> Nice example of cargo cult programming, thanks for fixing this!
Maybe now would be a good time to look at other drivers. Does the
Microsemi Ocelot driver have the same issue?
Andrew
next prev parent reply other threads:[~2019-02-20 17:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 10:32 [PATCH net] net: dsa: fix unintended change of bridge interface STP state Russell King
2019-02-20 16:38 ` Vivien Didelot
2019-02-20 17:22 ` Florian Fainelli
2019-02-20 17:27 ` Andrew Lunn [this message]
2019-02-20 18:38 ` Florian Fainelli
2019-02-20 19:09 ` David Miller
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