linux-kernel - Re: [PATCH] Do not disable driver and bus shutdown hook when class shutdown hook is set.

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Date:   Fri, 11 Aug 2017 14:50:56 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:     Michal Suchanek <msuchanek@...e.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        linux-kernel@...r.kernel.org, tpmdd-devel@...ts.sourceforge.net
Subject: Re: [PATCH] Do not disable driver and bus shutdown hook when class
 shutdown hook is set.

On Wed, Aug 09, 2017 at 03:52:02PM -0600, Jason Gunthorpe wrote:
> On Wed, Aug 09, 2017 at 11:34:20PM +0200, Michal Suchanek wrote:
> > Disabling the driver hook by setting class hook is totally sound design
> > not prone to error as evidenced by the single implementation of the
> > class hook.
> 
> It was done this was for consistency, if you look at the full code:
> 
>                 if (dev->class && dev->class->shutdown) {
>                         if (initcall_debug)
>                                 dev_info(dev, "shutdown\n");
>                         dev->class->shutdown(dev);
>                 } else if (dev->bus && dev->bus->shutdown) {
>                         if (initcall_debug)
>                                 dev_info(dev, "shutdown\n");
>                         dev->bus->shutdown(dev);
>                 } else if (dev->driver && dev->driver->shutdown) {
>                         if (initcall_debug)
>                                 dev_info(dev, "shutdown\n");
>                         dev->driver->shutdown(dev);
>                 }
> 
> The bus disables the driver callback, on the expectation that the bus
> implementation will do it.
> 
> Existing bus implementations do properly chain to driver shutdown (eg
> look at mmc_bus_shutdown) and it appears to have been written like
> this so that the bus can insert code before and after calling the
> driver shutdown.
> 
> Making class act differently from bus seems very confusing, IHMO,
> which why the TPM patch was written to follow the existing pattern.
> 
> Jason

There's also more fundamental problem. There are Fixes tags but no
real regression. Even if this patch made sense I would not consider
it as a bug fix.

/Jarkko