drm/i915/crt: Flush register prior to waiting for vblank.
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / block / noop-iosched.c
blob232c4b38cd3769d31e0c79700a49f42915c683a6
1 /*
2 * elevator noop
3 */
4 #include <linux/blkdev.h>
5 #include <linux/elevator.h>
6 #include <linux/bio.h>
7 #include <linux/module.h>
8 #include <linux/slab.h>
9 #include <linux/init.h>
11 struct noop_data {
12 struct list_head queue;
15 static void noop_merged_requests(struct request_queue *q, struct request *rq,
16 struct request *next)
18 list_del_init(&next->queuelist);
21 static int noop_dispatch(struct request_queue *q, int force)
23 struct noop_data *nd = q->elevator->elevator_data;
25 if (!list_empty(&nd->queue)) {
26 struct request *rq;
27 rq = list_entry(nd->queue.next, struct request, queuelist);
28 list_del_init(&rq->queuelist);
29 elv_dispatch_sort(q, rq);
30 return 1;
32 return 0;
35 static void noop_add_request(struct request_queue *q, struct request *rq)
37 struct noop_data *nd = q->elevator->elevator_data;
39 list_add_tail(&rq->queuelist, &nd->queue);
42 static int noop_queue_empty(struct request_queue *q)
44 struct noop_data *nd = q->elevator->elevator_data;
46 return list_empty(&nd->queue);
49 static struct request *
50 noop_former_request(struct request_queue *q, struct request *rq)
52 struct noop_data *nd = q->elevator->elevator_data;
54 if (rq->queuelist.prev == &nd->queue)
55 return NULL;
56 return list_entry(rq->queuelist.prev, struct request, queuelist);
59 static struct request *
60 noop_latter_request(struct request_queue *q, struct request *rq)
62 struct noop_data *nd = q->elevator->elevator_data;
64 if (rq->queuelist.next == &nd->queue)
65 return NULL;
66 return list_entry(rq->queuelist.next, struct request, queuelist);
69 static void *noop_init_queue(struct request_queue *q)
71 struct noop_data *nd;
73 nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
74 if (!nd)
75 return NULL;
76 INIT_LIST_HEAD(&nd->queue);
77 return nd;
80 static void noop_exit_queue(struct elevator_queue *e)
82 struct noop_data *nd = e->elevator_data;
84 BUG_ON(!list_empty(&nd->queue));
85 kfree(nd);
88 static struct elevator_type elevator_noop = {
89 .ops = {
90 .elevator_merge_req_fn = noop_merged_requests,
91 .elevator_dispatch_fn = noop_dispatch,
92 .elevator_add_req_fn = noop_add_request,
93 .elevator_queue_empty_fn = noop_queue_empty,
94 .elevator_former_req_fn = noop_former_request,
95 .elevator_latter_req_fn = noop_latter_request,
96 .elevator_init_fn = noop_init_queue,
97 .elevator_exit_fn = noop_exit_queue,
99 .elevator_name = "noop",
100 .elevator_owner = THIS_MODULE,
103 static int __init noop_init(void)
105 elv_register(&elevator_noop);
107 return 0;
110 static void __exit noop_exit(void)
112 elv_unregister(&elevator_noop);
115 module_init(noop_init);
116 module_exit(noop_exit);
119 MODULE_AUTHOR("Jens Axboe");
120 MODULE_LICENSE("GPL");
121 MODULE_DESCRIPTION("No-op IO scheduler");