Re: [PATCH v2 12/14] torture: Replace cpu_up/down with device_online/offline

[Paul E. McKenney]

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@xxxxxxx>
> > > > CC: Davidlohr Bueso <dave@xxxxxxxxxxxx>
> > > > CC: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> > > > CC: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
> > > > CC: linux-kernel@xxxxxxxxxxxxxxx
> > > 
> > > 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.)

							Thanx, Paul