Date: Fri, 11 Aug 2017 12:28:57 -0300
From: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
To: Michal =?iso-8859-1?Q?Such=E1nek?= <msuchanek@suse.de>
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Huewe <peterhuewe@gmx.de>, Marcel Selhorst <tpmdd@selhorst.net>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        linux-kernel@vger.kernel.org, tpmdd-devel@lists.sourceforge.net
Subject: Re: [PATCH] Do not disable driver and bus shutdown hook when class
 shutdown hook is set.
Message-ID: <20170811152857.cgjvlkiilskv76o3@khazad-dum.debian.net>
References: <20170809213420.2391-1-msuchanek@suse.de>
 <20170809215202.GA21867@obsidianresearch.com>
 <20170810121811.2741dccc@kitsune.suse.cz>
 <20170810163057.GA21485@obsidianresearch.com>
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On Fri, 11 Aug 2017, Michal Such?nek wrote:
> On 2017-08-10 18:30, Jason Gunthorpe wrote:
> > On Thu, Aug 10, 2017 at 12:18:11PM +0200, Michal Such?nek wrote:
> > > > Existing bus implementations do properly chain to driver shutdown (eg
> > > > look at mmc_bus_shutdown) and it appears to have been written like
> > > 
> > > Neither isa nor ibmebus does. These are two random buses I tried to
> > > look at.
> > 
> > I'm not following, I see this:
> > 
> > static void ibmebus_bus_device_shutdown(struct device *dev)
> > {
> >         struct platform_device *of_dev = to_platform_device(dev);
> >         struct platform_driver *drv = to_platform_driver(dev->driver);
> > 
> >         if (dev->driver && drv->shutdown)
> >                 drv->shutdown(of_dev);
> > }
> > 
> > It looks to me like in this case the struct device_driver shutdown is
> > not used, and instead the struct platform_driver shutdown is called.
> 
> And it is not used even if a device driver sets it and expects it to run.

Which is the kind of landmine it is best avoided in drivers/, so it
would be nice to get WARN_ON() during device register when
dev->shutdown() methods *that are going to be ignored* because of
class/bus handlers are non-NULL...

Either that, or the device->shutdown() methods should always be called,
and drivers that should not/need not have them should be fixed...

-- 
  Henrique Holschuh