drm/radeon/kms: fix for radeon on systems >4GB without hardware iommu
[linux-2.6.git] / block / noop-iosched.c
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>
10
11 struct noop_data {
12         struct list_head queue;
13 };
14
15 static void noop_merged_requests(struct request_queue *q, struct request *rq,
16                                  struct request *next)
17 {
18         list_del_init(&next->queuelist);
19 }
20
21 static int noop_dispatch(struct request_queue *q, int force)
22 {
23         struct noop_data *nd = q->elevator->elevator_data;
24
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;
31         }
32         return 0;
33 }
34
35 static void noop_add_request(struct request_queue *q, struct request *rq)
36 {
37         struct noop_data *nd = q->elevator->elevator_data;
38
39         list_add_tail(&rq->queuelist, &nd->queue);
40 }
41
42 static struct request *
43 noop_former_request(struct request_queue *q, struct request *rq)
44 {
45         struct noop_data *nd = q->elevator->elevator_data;
46
47         if (rq->queuelist.prev == &nd->queue)
48                 return NULL;
49         return list_entry(rq->queuelist.prev, struct request, queuelist);
50 }
51
52 static struct request *
53 noop_latter_request(struct request_queue *q, struct request *rq)
54 {
55         struct noop_data *nd = q->elevator->elevator_data;
56
57         if (rq->queuelist.next == &nd->queue)
58                 return NULL;
59         return list_entry(rq->queuelist.next, struct request, queuelist);
60 }
61
62 static void *noop_init_queue(struct request_queue *q)
63 {
64         struct noop_data *nd;
65
66         nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
67         if (!nd)
68                 return NULL;
69         INIT_LIST_HEAD(&nd->queue);
70         return nd;
71 }
72
73 static void noop_exit_queue(struct elevator_queue *e)
74 {
75         struct noop_data *nd = e->elevator_data;
76
77         BUG_ON(!list_empty(&nd->queue));
78         kfree(nd);
79 }
80
81 static struct elevator_type elevator_noop = {
82         .ops = {
83                 .elevator_merge_req_fn          = noop_merged_requests,
84                 .elevator_dispatch_fn           = noop_dispatch,
85                 .elevator_add_req_fn            = noop_add_request,
86                 .elevator_former_req_fn         = noop_former_request,
87                 .elevator_latter_req_fn         = noop_latter_request,
88                 .elevator_init_fn               = noop_init_queue,
89                 .elevator_exit_fn               = noop_exit_queue,
90         },
91         .elevator_name = "noop",
92         .elevator_owner = THIS_MODULE,
93 };
94
95 static int __init noop_init(void)
96 {
97         elv_register(&elevator_noop);
98
99         return 0;
100 }
101
102 static void __exit noop_exit(void)
103 {
104         elv_unregister(&elevator_noop);
105 }
106
107 module_init(noop_init);
108 module_exit(noop_exit);
109
110
111 MODULE_AUTHOR("Jens Axboe");
112 MODULE_LICENSE("GPL");
113 MODULE_DESCRIPTION("No-op IO scheduler");