More info about kobj_attribute store and show functions

Sept. 4, 2014

      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);

if (count == 13) {
 if (buffer) {
        copy_from_user(buffer, buf, count);
printk("A %s",buffer);
 if (0) {
if (strcmp(buffer, eudyptula_id) == 0)
 return count;
        printk("erro na strcmp\n");
}
 else
printk("erro na copia\n");
 }
}
return -EINVAL;
}

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

--
Lucas Tanure
+55 (19) 988176559