Re: [char-misc-next 04/11 V2] uuid: extract macros for assigning raw arrays

On Wed, May 27, 2015 at 05:24:01PM +0000, Winkler, Tomas wrote:

quoted

On Wed, May 27, 2015 at 06:42:13PM +0300, Tomas Winkler wrote:

quoted

In order for mei client devices to use device id based on uuid we
have to use common types between user space (file2alias.c).
Similarly to vmbus,  mei  uses raw 16 byte array for that.
To leverage on existing infrastructure around uuid_le type
defined in uuid.h we add helper macros to handle conversions between
raw 16 byte array and uuid_{le,be} types.

You aren't adding a helper macro, you are just redefining the existing
macros using a different one. 

Not exactly I'm using both the one I've added for device ids and the old one for all the other flows.

 But I can't see why this is needed, what

quoted

does this solve that vmbus and other uses of the existing macros don't
need?  In other words, what makes mei so special that it needs a "lower"
level macro than every other subsystem?

It's not special there is actually a lot of code duplication around uuid handling 
every subsystem is using their own macros but it can be consolidated around uuid.h
 
So vmbus can use that 
Instead of 
/*
 * Network GUID
 * {f8615163-df3e-46c5-913f-f2d2f965ed0e}
 */
#define HV_NIC_GUID \
        .guid = { \
                        0x63, 0x51, 0x61, 0xf8, 0x3e, 0xdf, 0xc5, 0x46, \
                        0x91, 0x3f, 0xf2, 0xd2, 0xf9, 0x65, 0xed, 0x0e \
                }

The can use the new macro to make it more readable, something in spirit of:

#define HV_NIC_GUID __UUID_LE(f8615163-df3e-46c5-913f-f2d2f965ed0e)

Why the "__" usage here?  That signifies a "private" namespace, why add
that to the user visible header files?

And are you going to send patches for vmbus and other drivers to fix
everything up to use these new macros?  Someone has to...

thanks,

greg k-h