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From: Andrew Lunn <andrew@lunn.ch>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Kurt Kanzenbach <kurt@linutronix.de>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	devicetree@vger.kernel.org,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Richard Cochran <richardcochran@gmail.com>,
	Kamil Alkhouri <kamil.alkhouri@hs-offenburg.de>,
	ilias.apalodimas@linaro.org
Subject: Re: [PATCH v4 2/7] net: dsa: Add DSA driver for Hirschmann Hellcreek switches
Date: Tue, 1 Sep 2020 17:59:45 +0200	[thread overview]
Message-ID: <20200901155945.GG2403519@lunn.ch> (raw)
In-Reply-To: <20200901142243.2jrurmfmh6znosxd@skbuf>

> > >
> > > What is the register lock protecting against, exactly?
> > 
> > A lot of the register operations work by:
> > 
> >  * Select port, priority, vlan or counter
> >  * Configure it
> > 
> > These sequences have to be atomic. That's what I wanted to ensure.
> > 
> 
> So, let me rephrase. Is there any code path that is broken, even if only
> theoretically, if you remove the reg_lock?

Maybe, at the moment, RTNL is keeping things atomic. But that is
because there is no HWMON, or MDIO bus. Those sort of operations don't
take the RTNL, and so would be an issue. I've also never audited the
network stack to check RTNL really is held at all the network stack
entry points to a DSA driver. It would be an interesting excesses to
scatter some ASSERT_RTNL() in a DSA driver and see what happens.

	Andrew

  reply	other threads:[~2020-09-01 16:01 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-01 12:50 [PATCH v4 0/7] Hirschmann Hellcreek DSA driver Kurt Kanzenbach
2020-09-01 12:50 ` [PATCH v4 1/7] net: dsa: Add tag handling for Hirschmann Hellcreek switches Kurt Kanzenbach
2020-09-01 12:50 ` [PATCH v4 2/7] net: dsa: Add DSA driver " Kurt Kanzenbach
2020-09-01 13:40   ` Vladimir Oltean
2020-09-01 14:05     ` Kurt Kanzenbach
2020-09-01 14:22       ` Vladimir Oltean
2020-09-01 15:59         ` Andrew Lunn [this message]
2020-09-01 16:36           ` Richard Cochran
2020-09-01 18:53             ` David Miller
2020-09-02  5:59               ` Kurt Kanzenbach
2020-09-01 15:11   ` kernel test robot
2020-09-01 12:50 ` [PATCH v4 3/7] net: dsa: hellcreek: Add PTP clock support Kurt Kanzenbach
2020-09-01 12:50 ` [PATCH v4 4/7] net: dsa: hellcreek: Add support for hardware timestamping Kurt Kanzenbach
2020-09-01 12:50 ` [PATCH v4 5/7] net: dsa: hellcreek: Add PTP status LEDs Kurt Kanzenbach
2020-09-03 16:32   ` Florian Fainelli
2020-09-01 12:50 ` [PATCH v4 6/7] dt-bindings: Add vendor prefix for Hirschmann Kurt Kanzenbach
2020-09-01 12:50 ` [PATCH v4 7/7] dt-bindings: net: dsa: Add documentation for Hellcreek switches Kurt Kanzenbach
2020-09-03 16:27   ` Rob Herring
2020-09-03 16:29   ` Florian Fainelli

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