Re: [PATCH v2] dell-wmi: Improve unknown hotkey handling

["Pali Rohár" <pali.rohar@gmail.com>]

On Friday 20 November 2015 17:30:13 Andy Lutomirski wrote:
> On Fri, Nov 20, 2015 at 5:27 PM, Andy Lutomirski <luto@kernel.org> wrote:
> > If DMI lists a hotkey that we don't recognize, log and ignore it
> > instead of trying to map it to keycode 0.  I haven't seen this happen,
> > but it will help maintain the key map in the future and it will help
> > avoid sending bogus events.
> >
> > This also improves the message that we log when we get an unknown key
> > event.
> >
> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
> > ---
> >
> > Changes from v1:
> >  - Use KEY_RESERVED instead of zero and document why that's okay
> >  - Fix scancode vs keycode confusion in the log message (whoops!)
> >  - Switch from hardcoded 256 to ARRAY_SIZE
> >
> >  drivers/platform/x86/dell-wmi.c | 25 +++++++++++++++++++++----
> >  1 file changed, 21 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
> > index d2daf5417cd7..cb96ef03fa79 100644
> > --- a/drivers/platform/x86/dell-wmi.c
> > +++ b/drivers/platform/x86/dell-wmi.c
> 
> 
> > +               /* Uninitialized entries are 0 aka KEY_RESERVED. */
> > +               BUILD_BUG_ON(KEY_RESERVED != 0);
> > +               u16 keycode = (bios_entry->keycode <
> > +                              ARRAY_SIZE(bios_to_linux_keycode)) ?
> > +                       bios_to_linux_keycode[bios_entry->keycode] :
> > +                       KEY_RESERVED;
> 
> Oops.  BUILD_BUG_ON should be below u16 keycode = ... to avoid a
> warning.  Feel free to fix it up.  I can also send a v3.

KEY_RESERVED is zero by definition and exported to user space. So this
should not be redefined otherwise Linux ABI will be broken too.

So I think BUILD_BUG_ON is not needed there.

-- 
Pali Rohár
pali.rohar@gmail.com