Re: More info about kobj_attribute store and show functions

[Lucas Tanure <tanure@xxxxxxxxx>]

Greg, 

I'm still trying to understand the sysfs. 

I indeed read the documentation, I was using your "Sample kobject implementation" as base of my code. But as 4h of work there some points that I didn't understand yet.

Thanks

--

Lucas Tanure 
+55 (19) 988176559

On Wed, Sep 3, 2014 at 9:23 PM, Greg KH <greg@xxxxxxxxx> wrote:

On Wed, Sep 03, 2014 at 09:10:41PM -0300, Lucas Tanure wrote:
> (Forget the last e-mail, please, stupid Gmail)
>
> Hi,
>
> I'm looking for some information about :
>
> struct kobj_attribute {
>         struct attribute attr;
>         ssize_t (*show)(struct kobject *kobj, struct kobj_attribute
> *attr, char *buf);
>         ssize_t (*store)(struct kobject *kobj, struct kobj_attribute
> *attr, const char *buf, size_t count);
> };
>
>
> My function to handle the operation:
>
> static ssize_t my_store(struct kobject *kobj, struct kobj_attribute *attr,
> const char *buf, size_t count) {
>  char *buffer;
>
>         buffer = (char*) kcalloc(count, sizeof(char), GFP_KERNEL);
>
>         copy_from_user(buffer, buf, count);
>         .....
>         .....
>         etc....
> }
>

> So, this *const char *buf, *where ti come from ? Kernel space?

I'm guessing you didn't read the kobject documentation that is in the
kernel tree?

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