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/*
* Oh dear. Task queues were removed from Linux 2.6 and replaced by work
* queues. Unfortunately the semantics is not the same. With task queues we
* can defer work until a particular event occurs -- this is not
* straightforwardly done with work queues (queued work is performed asap, or
* after some fixed timeout). Conversely, work queues are a (slightly) neater
* way of deferring work to a process context than using task queues in 2.4.
*
* This is a bit of a needless reimplementation -- should have just pulled
* the code from 2.4, but I tried leveraging work queues to simplify things.
* They didn't help. :-(
*/
#ifndef __QUEUES_H__
#define __QUEUES_H__
#include <linux/version.h>
#include <linux/list.h>
#include <linux/workqueue.h>
struct tq_struct {
void (*fn)(void *);
void *arg;
struct list_head list;
unsigned long pending;
};
#define INIT_TQUEUE(_name, _fn, _arg) \
do { \
INIT_LIST_HEAD(&(_name)->list); \
(_name)->pending = 0; \
(_name)->fn = (_fn); (_name)->arg = (_arg); \
} while ( 0 )
#define DECLARE_TQUEUE(_name, _fn, _arg) \
struct tq_struct _name = { (_fn), (_arg), LIST_HEAD_INIT((_name).list), 0 }
typedef struct {
struct list_head list;
spinlock_t lock;
} task_queue;
#define DECLARE_TASK_QUEUE(_name) \
task_queue _name = { LIST_HEAD_INIT((_name).list), SPIN_LOCK_UNLOCKED }
static inline int queue_task(struct tq_struct *tqe, task_queue *tql)
{
unsigned long flags;
if ( test_and_set_bit(0, &tqe->pending) )
return 0;
spin_lock_irqsave(&tql->lock, flags);
list_add_tail(&tqe->list, &tql->list);
spin_unlock_irqrestore(&tql->lock, flags);
return 1;
}
static inline void run_task_queue(task_queue *tql)
{
struct list_head head, *ent;
struct tq_struct *tqe;
unsigned long flags;
void (*fn)(void *);
void *arg;
spin_lock_irqsave(&tql->lock, flags);
list_add(&head, &tql->list);
list_del_init(&tql->list);
spin_unlock_irqrestore(&tql->lock, flags);
while ( !list_empty(&head) )
{
ent = head.next;
list_del_init(ent);
tqe = list_entry(ent, struct tq_struct, list);
fn = tqe->fn;
arg = tqe->arg;
wmb();
tqe->pending = 0;
fn(arg);
}
}
#endif /* __QUEUES_H__ */
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