Hi Jim:
> > On Thu, Aug 17, 2006 at 01:35:30PM -0600, Jim Cromie wrote:
> >> Um.. I just looked at asb100.c, and Im seeing static decls like:
> >> static DEVICE_ATTR(..)
> >>
> >> Unless Im misunderstanding something, this is sufficient to preclude
> >> supporting a 2nd device.
> >> IOW, to support multiple devices, drivers would need to create
> >> attributes, groups, etc out of
> >> kalloc'd memory, sacrificing the (heavy) use of static initialization in
> >> hwmon/*.c
> Greg KH wrote:
> > No, you are incorrect, it will work just fine. The dynamic thing is the
> > struct device, not the functions that make up the file callbacks.
... nor the accompanying struct attributes, nor the struct attribute_group.
* Jim Cromie <jim.cromie at gmail.com> [2006-08-17 15:45:06 -0600]:
> Im not speaking of the callbacks themselves, rather the
> device_attributes that
> keep references to them. Assuming 2 'static DEVICE_ATTR()'s,
> that are init'd with names "in0_max", "in1_max". theyre separate
> attributes,
> reusing the same show,store functions, thru separate refs. Correct ?
>
> Are you saying that I could reuse a statically defined group (ie the
> device_attrs within it)
> to create another set of attr-files ?
I won't presume to speak for Greg, but yes I think that works fine too.
It's a reasonable question though. I wondered about it for a little bit
when I saw that struct attribute_group seems to be missing two const
modifiers, i.e.:
--- linux-2.6.18-rc4-mm1.orig/include/linux/sysfs.h
+++ linux-2.6.18-rc4-mm1/include/linux/sysfs.h
@@ -24,7 +24,7 @@ struct attribute {
struct attribute_group {
const char * name;
- struct attribute ** attrs;
+ const struct attribute * const * attrs;
};
But actually compiling a kernel with the above introduces a ton of warnings.
All those I examined could be fixed by adding const to struct attribute
declarations (AFAICT nobody is actually modifying any data through those
pointers), but I haven't looked at them all, and it's late here, blah...
Anyway, Jim if you look at the actual implementation of sysfs_add_group()
it should become apparent that the attribute structures can be shared.
Regards,
--
Mark M. Hoffman
mhoffman at lightlink.com
