From: Greg KH <gregkh@linuxfoundation.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>,
Peter Rajnoha <prajnoha@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2] powerpc/vio: drop bus_type from parent device
Date: Thu, 30 Jul 2020 07:37:16 +0200 [thread overview]
Message-ID: <20200730053716.GA3862178@kroah.com> (raw)
In-Reply-To: <87ime56bax.fsf@mpe.ellerman.id.au>
On Thu, Jul 30, 2020 at 11:28:38AM +1000, Michael Ellerman wrote:
> [ Added Peter & Greg to Cc ]
>
> Thadeu Lima de Souza Cascardo <cascardo@canonical.com> writes:
> > Commit df44b479654f62b478c18ee4d8bc4e9f897a9844 ("kobject: return error
> > code if writing /sys/.../uevent fails") started returning failure when
> > writing to /sys/devices/vio/uevent.
> >
> > This causes an early udevadm trigger to fail. On some installer versions of
> > Ubuntu, this will cause init to exit, thus panicing the system very early
> > during boot.
> >
> > Removing the bus_type from the parent device will remove some of the extra
> > empty files from /sys/devices/vio/, but will keep the rest of the layout
> > for vio devices, keeping them under /sys/devices/vio/.
>
> What exactly does it change?
>
> I'm finding it hard to evaluate if this change is going to cause a
> regression somehow.
>
> I'm also not clear on why removing the bus type is correct, apart from
> whether it fixes the bug you're seeing.
>
> > It has been tested that uevents for vio devices don't change after this
> > fix, they still contain MODALIAS.
> >
> > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
> > Fixes: df44b479654f ("kobject: return error code if writing /sys/.../uevent fails")
>
> AFAICS there haven't been any other fixes for that commit. Do we know
> why it is only vio that was affected? (possibly because it's a fake bus
> to begin with?)
So there was an error previously, the core was ignoring it, and now it
isn't and to fix that you want to remove describing what bus a device is
on?
Huh???
>
> cheers
>
> > diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
> > index 37f1f25ba804..a94dab3972a0 100644
> > --- a/arch/powerpc/platforms/pseries/vio.c
> > +++ b/arch/powerpc/platforms/pseries/vio.c
> > @@ -36,7 +36,6 @@ static struct vio_dev vio_bus_device = { /* fake "parent" device */
> > .name = "vio",
> > .type = "",
> > .dev.init_name = "vio",
> > - .dev.bus = &vio_bus_type,
> > };
Wait, a static 'struct device'? You all are playing with fire there.
That's a reference counted object, and should never be declared like
that at all.
I see you register it, but never unregister it, why? Why is it even
needed?
And if you remove the bus type of it, it will show up in a different
part of sysfs, so I think this patch will show a user-visable change,
right?
thanks,
greg k-h
next prev parent reply other threads:[~2020-07-30 5:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 15:57 [PATCH v2] powerpc/vio: drop bus_type from parent device Thadeu Lima de Souza Cascardo
2020-07-30 1:28 ` Michael Ellerman
2020-07-30 5:37 ` Greg KH [this message]
2020-07-30 15:35 ` Thadeu Lima de Souza Cascardo
2020-07-31 0:53 ` Michael Ellerman
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