Re: [PATCH] drivers/irqchip: Remove function callback casts

Marc Zyngier
2020-05-24T16:16:45Z

On 2020-05-24 17:06, Oscar Carter wrote:
> Hi Marc,
>
> On Sun, May 24, 2020 at 12:46:34PM +0100, Marc Zyngier wrote:
>> On Sun, 24 May 2020 10:09:10 +0200
>> Oscar Carter <oscar.carter@gmx.com> wrote:
>>
>> Hi Oscar,
>>
>> Thanks for this. Comments below.
>>
>> > In an effort to enable -Wcast-function-type in the top-level Makefile to
>> > support Control Flow Integrity builds, remove all the function callback
>> > casts.
>> >
>> > To do this, modify the IRQCHIP_ACPI_DECLARE macro initializing the
>> > acpi_probe_entry struct directly instead of use the existent macro
>> > ACPI_DECLARE_PROBE_ENTRY.
>> >
>> > In this new initialization use the probe_subtbl field instead of the
>> > probe_table field use in the ACPI_DECLARE_PROBE_ENTRY macro.
>>
>> Please add *why* this is a valid transformation (probe_table and
>> probe_subtbl are part of a union).
>
> Ok, I will add a more detailed explanation.
>
>> > Signed-off-by: Oscar Carter <oscar.carter@gmx.com>
>> > ---
>> > include/linux/irqchip.h | 10 ++++++++--
>> > 1 file changed, 8 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/include/linux/irqchip.h b/include/linux/irqchip.h
>> > index 950e4b2458f0..1f464fd10df0 100644
>> > --- a/include/linux/irqchip.h
>> > +++ b/include/linux/irqchip.h
>> > @@ -39,8 +39,14 @@
>> > * @fn: initialization function
>> > */
>> > #define IRQCHIP_ACPI_DECLARE(name, subtable, validate, data, fn) \
>> > - ACPI_DECLARE_PROBE_ENTRY(irqchip, name, ACPI_SIG_MADT, \
>> > - subtable, validate, data, fn)
>> > + static const struct acpi_probe_entry __acpi_probe_##name \
>> > + __used __section(__irqchip_acpi_probe_table) = { \
>> > + .id = ACPI_SIG_MADT, \
>> > + .type = subtable, \
>> > + .subtable_valid = validate, \
>> > + .probe_subtbl = (acpi_tbl_entry_handler)fn, \
>> > + .driver_data = data, \
>> > + }
>> >
>>
>> I'd rather you add an ACPI_DECLARE_SUBTABLE_PROBE_ENTRY to acpi.h, and
>> use that here so that we can keep the ACPI gunk in a single place.
>
> Ok, I will do the changes you suggested and I will resend a new
> version.
> Later, I will also send a series to clean up the checkpatch warnings
> and
> errors for the acpi.h header.

Not necessarily a good idea. Churn for the sake of keeping checkpatch
at bay is pretty pointless. Do fix bugs if you spot any, but please
exercise judgement.

Thanks,

M.
--
Jazz is not dead. It just smells funny...