Re: [PATCH v2 5/8] platform/x86: fujitsu-laptop: track the last instantiated FUJ02E3 ACPI device
From: MichaÅ KÄpieÅ
Date: Tue May 23 2017 - 17:47:20 EST
> On Fri, May 19, 2017 at 09:44:45AM +0200, Micha?? K??pie?? wrote:
> > It is easier to simply store a module-wide
> > pointer to the last (most likely only) FUJ02E3 ACPI device found, make
> > the aforementioned API use it and cover our bases by warning the user if
> > firmware exposes multiple FUJ02E3 ACPI devices.
> > :
> > @@ -788,6 +789,9 @@ static int acpi_fujitsu_laptop_add(struct acpi_device *device)
> > if (!priv)
> > return -ENOMEM;
> > + WARN_ONCE(fext, "More than one FUJ02E3 ACPI device was found. Driver may not work as intended.");
> > + fext = device;
> > +
> > fujitsu_laptop = priv;
> > fujitsu_laptop->acpi_handle = device->handle;
> > sprintf(acpi_device_name(device), "%s",
> I thought WARN_ONCE() printed the warning when it was encountered for the
> first time and then suppressed it on all other occasions.
> If this is true
> then we'll get the warning even when there is only one FUJ02E3 in the
> system. Am I missing something?
Probably the fact that the first argument of the macro is a conditional
expression ("fext" is functionally equivalent to "fext != NULL" in this
case). In other words, the warning will only ever be issued if
acpi_fujitsu_laptop_add() is called at least twice - note the assignment
on the line following WARN_ONCE().