[PATCH v1 1/2] firewire: Simplify storing pointers in device id struct

On all current Linux architectures sizeof(long) == sizeof(void *) and
this is used a lot through the kernel. For example it enables the usual
practice to store pointers in ieee1394_device_id's .driver_data member.

This works fine, but involves casting and thus isn't type-safe.
Additionally with the CHERI architecture extension there are machines
with sizeof(void *) > sizeof(long) for with the traditional approach of
storing a pointer in .driver_data doesn't work.

By replacing the plain unsigned long .driver_data by an anonymous union,
most of the casting can be dropped and it yields a working solution for
CHERI.

All users of struct ieee1394_device_id are initialized in a way that is
compatible with the new definition, so no adaptions are needed there.

Signed-off-by: Uwe Kleine-König (The Capable Hub) <[email protected]>
---
 include/linux/mod_devicetable.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 5b1725fe9707..2ee6b66ca9a2 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -61,7 +61,10 @@ struct ieee1394_device_id {
 	__u32 model_id;
 	__u32 specifier_id;
 	__u32 version;
-	kernel_ulong_t driver_data;
+	union {
+		kernel_ulong_t driver_data;
+		const void *driver_data_ptr;
+	};
 };
 
 
-- 
2.47.3