From: Greg KH <greg@kroah.com>
To: Len Baker <len.baker@gmx.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
Kees Cook <keescook@chromium.org>,
Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
Mark Gross <mgross@linux.intel.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
ibm-acpi-devel@lists.sourceforge.net,
platform-driver-x86@vger.kernel.org,
linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] platform/x86: thinkpad_acpi: Prefer struct_size over open coded arithmetic
Date: Sat, 25 Sep 2021 13:07:20 +0200 [thread overview]
Message-ID: <YU8C6B5zw5t4vsh7@kroah.com> (raw)
In-Reply-To: <20210925081856.GD1660@titan>
On Sat, Sep 25, 2021 at 12:40:44PM +0200, Len Baker wrote:
> Hi,
>
> On Tue, Sep 21, 2021 at 05:15:35PM +0200, Greg KH wrote:
> >
> > First off, why is a single driver doing so many odd things with
> > attribute groups? Why not just use them the way that the rest of the
> > kernel does? Why does this driver need this special handling and no one
> > else does?
>
> Is [1] the correct way to deal with devices attributes? I think so.
>
> [1] https://www.kernel.org/doc/html/latest/driver-api/driver-model/driver.html#attributes
No, do not use driver_create_file(), see:
http://kroah.com/log/blog/2013/06/26/how-to-create-a-sysfs-file-correctly/
as a more up to date thing.
Someone should fix that in-kernel documentation one day :)
> > I think the default way of handling if an attribute is enabled or not,
> > should suffice here, and make things much simpler overall as all of this
> > crazy attribute handling can just be removed.
>
> Sorry but what is the default way? Would it be correct to check if the
> file exists?
Use the is_visable() callback for the attribute group to enable/disable
the creation of the sysfs file.
> > Bonus would also be that I think it would fix the race conditions that
> > happen when trying to create attributes after the device is bound to the
> > driver that I think the existing driver has today.
> >
> > > > (I see the caller uses +2? Why? It seems to be using each of hotkey_attributes,
> > > > plus 1 more attr, plus a final NULL?)
> > >
> > > The +2 is actually for 2 extra attributes (making the total number
> > > of extra attributes +3 because the sizeof(struct attribute_set_obj)
> > > already includes 1 extra).
> > >
> > > FWIW these 2 extra attributes are for devices with a
> > > a physical rfkill on/off switch and for the device being
> > > a convertible capable of reporting laptop- vs tablet-mode.
> >
> > Again, using the default way to show (or not show) attributes should
> > solve this issue. Why not just use that instead?
>
> What is the default way? Would it be correct to use device_create_file()
> and device_remove_file()?
Put all the attributes into an attribute group and attach it to the
driver. The driver core will create/remove the files when needed. The
link above should help explain that a bit better, and I can point you at
examples if needed.
Does that help?
thanks,
greg k-h
next prev parent reply other threads:[~2021-09-25 11:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-18 15:05 [PATCH] platform/x86: thinkpad_acpi: Prefer struct_size over open coded arithmetic Len Baker
2021-09-20 5:58 ` Kees Cook
2021-09-21 13:46 ` Hans de Goede
2021-09-21 15:15 ` Greg KH
2021-09-21 15:38 ` Hans de Goede
2021-09-21 15:45 ` Greg KH
2021-09-25 10:40 ` Len Baker
2021-09-25 11:07 ` Greg KH [this message]
2021-09-25 13:33 ` Len Baker
2021-09-25 10:37 ` Len Baker
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