Problem: plist_add undefined!

Problem: plist_add undefined!

[Monica Puig-Pey]

Hi there,

As I told in previous posts in this list I'm developing drivers for the

linux-rt kernel version in Ubuntu 10.04, based on 2.6.31 with rt_preempt 
patch.

Currently I'm studying how to use priority lists (linux/plist.h) in a 
module. I read some pages from the Linux Kernel Development book to 
learn how linked list work in the kernel.

I made and easy example, shown below, trying to put three elements, with 
their priorities, in a plist_head.

Then, I had two problems:

* First error:

   An error is produced when using the MACROs:
     - PLIST_HEAD_INIT(head, _lock)
     - PLIST_NODE_INIT(node, __prio)

   it says :


/home/monica/Escritorio/plists/priolist.c: In function 'init_module': 
/home/monica/Escritorio/plists/priolist.c:67: error: expected expression 
before '.' token


   --> To solve this I used the functions:


- static inline void plist_head_init(struct plist_head *head, struct 
spinlock *lock)

- static inline void plist_node_init(struct plist_node *node, int prio)

   But I still have the problem with the MACRO




* Second error, problem using plist_add:

   It says:


“WARNING: "plist_add" [/home/monica/Escritorio/plists/priolist.ko] 
undefined! ”

   I made the module GPL, I don't know what am I doing wrong.

Does anybody have an idea what is happening?

Thanks in advance for any help,

Cheers,

         Monica

CODE:

#include <linux/module.h>	
#include <linux/kernel.h>
#include <linux/ioport.h>
#include <linux/plist.h>
#include <linux/spinlock.h>


MODULE_LICENSE("GPL");

#define pid_miguel 1
#define fichero_miguel 1
#define prio_miguel 10


#define pid_monica 2
#define fichero_monica 1
#define prio_monica 30

#define pid_hector 3
#define fichero_hector 1
#define prio_hector 20



static DEFINE_SPINLOCK(lock);


struct misdatos
{
   int pid;
   int fichero;
   struct plist_node token_del_plist;
};


int init_module(void)
{


   struct plist_head mi_lista_de_datos;
   //struct spinlock lock;
   struct misdatos datos_miguel;
   struct misdatos datos_monica;
   struct misdatos datos_hector;

   struct misdatos *elemento_iterador;

   // Inicializo mi lista
   //PLIST_HEAD_INIT( mi_lista_de_datos, lock);
   plist_head_init( &mi_lista_de_datos, &lock);

   // Creo mis datos
   datos_miguel.pid = pid_miguel;
   datos_miguel.fichero = fichero_miguel;

   datos_monica.pid = pid_monica;
   datos_monica.fichero = fichero_monica;

   datos_hector.pid = pid_hector;
   datos_hector.fichero = fichero_hector;

   // Inicializamos los nodos CON LA PRIORIDAD
   //PLIST_NODE_INIT(datos_miguel.token_del_plist, prio_miguel);
   //PLIST_NODE_INIT(datos_monica.token_del_plist, prio_monica);
   //PLIST_NODE_INIT(datos_hector.token_del_plist, prio_hector);
   plist_node_init(&datos_miguel.token_del_plist, prio_miguel);
   plist_node_init(&datos_monica.token_del_plist, prio_monica);
   plist_node_init(&datos_hector.token_del_plist, prio_hector);


   // Los agnadimos
   plist_add(&(datos_miguel.token_del_plist), &mi_lista_de_datos);
   plist_add(&(datos_monica.token_del_plist), &mi_lista_de_datos);
   plist_add(&(datos_hector.token_del_plist), &mi_lista_de_datos);




plist_for_each_entry(elemento_iterador, &mi_lista_de_datos, token_del_plist)

   {

printk(KERN_INFO "El pid es : %d, con prioridad %d\n", 
elemento_iterador->pid, elemento_iterador->token_del_plist.prio);

   }
   return 0;
}

void cleanup_module(void)
{
printk(KERN_INFO "cleanup_module() called\n");

}
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Problem: plist_add undefined!

[Steven Rostedt]

On Tue, 2011-12-20 at 10:24 +0100, Monica Puig-Pey wrote:
> Hi there,
> 
> As I told in previous posts in this list I'm developing drivers for the
> 
> linux-rt kernel version in Ubuntu 10.04, based on 2.6.31 with rt_preempt 
> patch.
> 
> Currently I'm studying how to use priority lists (linux/plist.h) in a 
> module. I read some pages from the Linux Kernel Development book to 
> learn how linked list work in the kernel.
> 
> I made and easy example, shown below, trying to put three elements, with 
> their priorities, in a plist_head.
> 
> Then, I had two problems:
> 
> * First error:
> 
>    An error is produced when using the MACROs:
>      - PLIST_HEAD_INIT(head, _lock)
>      - PLIST_NODE_INIT(node, __prio)

Right, the macros are for static declarations. Either global variables
or a variable marked as static:

struct plist_head myhead = PLIST_HEAD_INIT(myhead, mylock);

or

int foo() {
	static struct plist_head bar = PLIST_HEAD_INIT(bar, mylock);

	[...]
}

or

struct foo bar = {
	.zoop = PLIST_HEAD_INIT(bar.zoop, mylock),
};


> 
>    it says :
> 
> 
> /home/monica/Escritorio/plists/priolist.c: In function 'init_module': 
> /home/monica/Escritorio/plists/priolist.c:67: error: expected expression 
> before '.' token
> 
> 
>    --> To solve this I used the functions:
> 
> 
> - static inline void plist_head_init(struct plist_head *head, struct 
> spinlock *lock)
> 
> - static inline void plist_node_init(struct plist_node *node, int prio)

Right, for runtime code you must use these.


> 
>    But I still have the problem with the MACRO
> 
> 
> 
> 
> * Second error, problem using plist_add:
> 
>    It says:
> 
> 
> “WARNING: "plist_add" [/home/monica/Escritorio/plists/priolist.ko] 
> undefined! ”

Simple, plist_add() isn't exported to modules.

Hmm, none of the plist functions are. I guess it wouldn't hurt to make
them EXPORT_SYMBOL_GPL()

Maybe we'll do that. Is this just for learning or are you planing on
adding a real GPL module to Linux that uses plists. For learning, it may
not be worth adding these symbols, but if you have a legit reason for
modules to use plists, than I don't see any harm in exporting them.

-- Steve

> 
>    I made the module GPL, I don't know what am I doing wrong.
> 
> Does anybody have an idea what is happening?
> 
> Thanks in advance for any help,
> 
> Cheers,
> 


--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html