ia64/xen-unstable

view linux-2.6-xen-sparse/drivers/xen/blkback/interface.c @ 13233:d275951acf10

[LINUX] Extend the event-channel interfaces to provide helper methods
for creating interdomain event channels bound to IRQ handlers.
Signed-off-by: Keir Fraser <keir@xensource.com>
author kaf24@localhost.localdomain
date Sat Dec 30 18:23:27 2006 +0000 (2006-12-30)
parents c3e20511c745
children c9ac0bace498
line source
1 /******************************************************************************
2 * arch/xen/drivers/blkif/backend/interface.c
3 *
4 * Block-device interface management.
5 *
6 * Copyright (c) 2004, Keir Fraser
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License version 2
10 * as published by the Free Software Foundation; or, when distributed
11 * separately from the Linux kernel or incorporated into other
12 * software packages, subject to the following license:
13 *
14 * Permission is hereby granted, free of charge, to any person obtaining a copy
15 * of this source file (the "Software"), to deal in the Software without
16 * restriction, including without limitation the rights to use, copy, modify,
17 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
18 * and to permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
20 *
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
30 * IN THE SOFTWARE.
31 */
33 #include "common.h"
34 #include <xen/evtchn.h>
35 #include <linux/kthread.h>
37 static kmem_cache_t *blkif_cachep;
39 blkif_t *blkif_alloc(domid_t domid)
40 {
41 blkif_t *blkif;
43 blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL);
44 if (!blkif)
45 return ERR_PTR(-ENOMEM);
47 memset(blkif, 0, sizeof(*blkif));
48 blkif->domid = domid;
49 spin_lock_init(&blkif->blk_ring_lock);
50 atomic_set(&blkif->refcnt, 1);
51 init_waitqueue_head(&blkif->wq);
52 blkif->st_print = jiffies;
53 init_waitqueue_head(&blkif->waiting_to_free);
55 return blkif;
56 }
58 static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
59 {
60 struct gnttab_map_grant_ref op;
61 int ret;
63 gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
64 GNTMAP_host_map, shared_page, blkif->domid);
66 lock_vm_area(blkif->blk_ring_area);
67 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
68 unlock_vm_area(blkif->blk_ring_area);
69 BUG_ON(ret);
71 if (op.status) {
72 DPRINTK(" Grant table operation failure !\n");
73 return op.status;
74 }
76 blkif->shmem_ref = shared_page;
77 blkif->shmem_handle = op.handle;
79 return 0;
80 }
82 static void unmap_frontend_page(blkif_t *blkif)
83 {
84 struct gnttab_unmap_grant_ref op;
85 int ret;
87 gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
88 GNTMAP_host_map, blkif->shmem_handle);
90 lock_vm_area(blkif->blk_ring_area);
91 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
92 unlock_vm_area(blkif->blk_ring_area);
93 BUG_ON(ret);
94 }
96 int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn)
97 {
98 blkif_sring_t *sring;
99 int err;
101 /* Already connected through? */
102 if (blkif->irq)
103 return 0;
105 if ( (blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE)) == NULL )
106 return -ENOMEM;
108 err = map_frontend_page(blkif, shared_page);
109 if (err) {
110 free_vm_area(blkif->blk_ring_area);
111 return err;
112 }
114 sring = (blkif_sring_t *)blkif->blk_ring_area->addr;
115 BACK_RING_INIT(&blkif->blk_ring, sring, PAGE_SIZE);
117 err = bind_interdomain_evtchn_to_irqhandler(
118 blkif->domid, evtchn, blkif_be_int, 0, "blkif-backend", blkif);
119 if (err < 0)
120 {
121 unmap_frontend_page(blkif);
122 free_vm_area(blkif->blk_ring_area);
123 return err;
124 }
125 blkif->irq = err;
127 return 0;
128 }
130 void blkif_disconnect(blkif_t *blkif)
131 {
132 if (blkif->xenblkd) {
133 kthread_stop(blkif->xenblkd);
134 blkif->xenblkd = NULL;
135 }
137 atomic_dec(&blkif->refcnt);
138 wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
139 atomic_inc(&blkif->refcnt);
141 if (blkif->irq) {
142 unbind_from_irqhandler(blkif->irq, blkif);
143 blkif->irq = 0;
144 }
146 if (blkif->blk_ring.sring) {
147 unmap_frontend_page(blkif);
148 free_vm_area(blkif->blk_ring_area);
149 blkif->blk_ring.sring = NULL;
150 }
151 }
153 void blkif_free(blkif_t *blkif)
154 {
155 if (!atomic_dec_and_test(&blkif->refcnt))
156 BUG();
157 kmem_cache_free(blkif_cachep, blkif);
158 }
160 void __init blkif_interface_init(void)
161 {
162 blkif_cachep = kmem_cache_create("blkif_cache", sizeof(blkif_t),
163 0, 0, NULL, NULL);
164 }