Messages in this thread | | | Date | Fri, 29 Nov 2019 09:13:45 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH v2 12/14] torture: Replace cpu_up/down with device_online/offline |
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On 11/28/19 13:02, Paul E. McKenney wrote: > On Thu, Nov 28, 2019 at 05:00:26PM +0000, Qais Yousef wrote: > > On 11/28/19 16:56, Qais Yousef wrote: > > > On 11/27/19 13:47, Paul E. McKenney wrote: > > > > On Mon, Nov 25, 2019 at 11:27:52AM +0000, Qais Yousef wrote: > > > > > The core device API performs extra housekeeping bits that are missing > > > > > from directly calling cpu_up/down. > > > > > > > > > > See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and > > > > > serialization during LPM") for an example description of what might go > > > > > wrong. > > > > > > > > > > This also prepares to make cpu_up/down a private interface for anything > > > > > but the cpu subsystem. > > > > > > > > > > Signed-off-by: Qais Yousef <qais.yousef@arm.com> > > > > > CC: Davidlohr Bueso <dave@stgolabs.net> > > > > > CC: "Paul E. McKenney" <paulmck@kernel.org> > > > > > CC: Josh Triplett <josh@joshtriplett.org> > > > > > CC: linux-kernel@vger.kernel.org > > > > > > > > Looks fine from an rcutorture viewpoint, but why not provide an API > > > > that pulled lock_device_hotplug() and unlock_device_hotplug() into the > > > > online/offline calls? > > > > > > I *think* the right way to do what you say is by doing lock_device_hotplug() > > > inside device_{online, offline}() - which affects all drivers not just the CPU. > > Or there could be a CPU-specific wrapper function that did the needed > locking. (Whether this is worth it or not of course depends on the > number of invocations.)
Okay I see what you mean now. driver/base/memory.c have {add,remove}_memory() that does what you say. I think we can replicate this in driver/base/cpu.c too.
I can certainly do that, better as an improvement on top as I need to audit the code to make sure the critical sections weren't relying on this lock to protect something else beside the online/offline operation.
Thanks!
-- Qais Yousef
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