#include <linux/module.h>
#include <linux/init.h>

MODULE_LICENSE("GPL");

static spinlock_t sl;

struct my_list {
   int counter;
   struct list_head link;
};
struct list_head rootptr;

static int show_listfunction_usage( void )
{
   int i;
   struct my_list *akt_element;
   struct list_head *loopvar, *tmp;

   for(i=0; i<5; i++) { // Liste anlegen
      // innerhalb der Critical Section darf nicht kmalloc() 
      // verwendet werden!
      akt_element = kmalloc(sizeof(struct my_list), GFP_USER);
      spin_lock(&sl);
      akt_element->counter = i;
      printk("adding: %p- %d\n", akt_element, i);
      list_add(&akt_element->link, &rootptr);
      spin_unlock(&sl);
   }
   spin_lock(&sl);
   list_for_each_safe(loopvar, tmp, &rootptr) { // Liste freigeben
      i = list_entry(loopvar, struct my_list, link)->counter;
      printk("delete: %p - %d\n", loopvar, i);
      list_del(loopvar);
      kfree(list_entry(loopvar,struct my_list, link));
   }
   spin_unlock(&sl);
   return 0;
}

static int __init modinit(void)
{
   INIT_LIST_HEAD(&rootptr);
   show_listfunction_usage();
   return -EIO;
}

static void __exit modexit(void)
{
   return;
}

module_init(modinit);
module_exit(modexit);