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1/******************************************************************************
2 * Talks to Xen Store to figure out what devices we have (backend half).
3 *
4 * Copyright (C) 2005 Rusty Russell, IBM Corporation
5 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
6 * Copyright (C) 2005, 2006 XenSource Ltd
7 * Copyright (C) 2007 Solarflare Communications, Inc.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
35
36#define DPRINTK(fmt, ...) \
37 pr_debug("(%s:%d) " fmt "\n", \
38 __func__, __LINE__, ##__VA_ARGS__)
39
40#include <linux/kernel.h>
41#include <linux/err.h>
42#include <linux/string.h>
43#include <linux/ctype.h>
44#include <linux/fcntl.h>
45#include <linux/mm.h>
46#include <linux/notifier.h>
47#include <linux/export.h>
48#include <linux/semaphore.h>
49
50#include <asm/page.h>
51#include <asm/xen/hypervisor.h>
52#include <asm/hypervisor.h>
53#include <xen/xenbus.h>
54#include <xen/features.h>
55
56#include "xenbus.h"
57
58/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
59static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
60{
61 int domid, err;
62 const char *devid, *type, *frontend;
63 unsigned int typelen;
64
65 type = strchr(nodename, '/');
66 if (!type)
67 return -EINVAL;
68 type++;
69 typelen = strcspn(type, "/");
70 if (!typelen || type[typelen] != '/')
71 return -EINVAL;
72
73 devid = strrchr(nodename, '/') + 1;
74
75 err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
76 "frontend", NULL, &frontend,
77 NULL);
78 if (err)
79 return err;
80 if (strlen(frontend) == 0)
81 err = -ERANGE;
82 if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
83 err = -ENOENT;
84 kfree(frontend);
85
86 if (err)
87 return err;
88
89 if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
90 typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
91 return -ENOSPC;
92 return 0;
93}
94
95static int xenbus_uevent_backend(const struct device *dev,
96 struct kobj_uevent_env *env)
97{
98 const struct xenbus_device *xdev;
99 const struct xenbus_driver *drv;
100 const struct xen_bus_type *bus;
101
102 DPRINTK("");
103
104 if (dev == NULL)
105 return -ENODEV;
106
107 xdev = to_xenbus_device(dev);
108 bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
109
110 if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
111 return -ENOMEM;
112
113 /* stuff we want to pass to /sbin/hotplug */
114 if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
115 return -ENOMEM;
116
117 if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
118 return -ENOMEM;
119
120 if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
121 return -ENOMEM;
122
123 if (dev->driver) {
124 drv = to_xenbus_driver(dev->driver);
125 if (drv && drv->uevent)
126 return drv->uevent(xdev, env);
127 }
128
129 return 0;
130}
131
132/* backend/<typename>/<frontend-uuid>/<name> */
133static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
134 const char *dir,
135 const char *type,
136 const char *name)
137{
138 char *nodename;
139 int err;
140
141 nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
142 if (!nodename)
143 return -ENOMEM;
144
145 DPRINTK("%s\n", nodename);
146
147 err = xenbus_probe_node(bus, type, nodename);
148 kfree(nodename);
149 return err;
150}
151
152/* backend/<typename>/<frontend-domid> */
153static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
154 const char *domid)
155{
156 char *nodename;
157 int err = 0;
158 char **dir;
159 unsigned int i, dir_n = 0;
160
161 DPRINTK("");
162
163 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
164 if (!nodename)
165 return -ENOMEM;
166
167 dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
168 if (IS_ERR(dir)) {
169 kfree(nodename);
170 return PTR_ERR(dir);
171 }
172
173 for (i = 0; i < dir_n; i++) {
174 err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
175 if (err)
176 break;
177 }
178 kfree(dir);
179 kfree(nodename);
180 return err;
181}
182
183static bool frontend_will_handle(struct xenbus_watch *watch,
184 const char *path, const char *token)
185{
186 return watch->nr_pending == 0;
187}
188
189static void frontend_changed(struct xenbus_watch *watch,
190 const char *path, const char *token)
191{
192 xenbus_otherend_changed(watch, path, token, 0);
193}
194
195static struct xen_bus_type xenbus_backend = {
196 .root = "backend",
197 .levels = 3, /* backend/type/<frontend>/<id> */
198 .get_bus_id = backend_bus_id,
199 .probe = xenbus_probe_backend,
200 .otherend_will_handle = frontend_will_handle,
201 .otherend_changed = frontend_changed,
202 .bus = {
203 .name = "xen-backend",
204 .match = xenbus_match,
205 .uevent = xenbus_uevent_backend,
206 .probe = xenbus_dev_probe,
207 .remove = xenbus_dev_remove,
208 .dev_groups = xenbus_dev_groups,
209 },
210};
211
212static void backend_changed(struct xenbus_watch *watch,
213 const char *path, const char *token)
214{
215 DPRINTK("");
216
217 xenbus_dev_changed(path, &xenbus_backend);
218}
219
220static struct xenbus_watch be_watch = {
221 .node = "backend",
222 .callback = backend_changed,
223};
224
225static int read_frontend_details(struct xenbus_device *xendev)
226{
227 return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
228}
229
230int xenbus_dev_is_online(struct xenbus_device *dev)
231{
232 return !!xenbus_read_unsigned(dev->nodename, "online", 0);
233}
234EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
235
236int __xenbus_register_backend(struct xenbus_driver *drv, struct module *owner,
237 const char *mod_name)
238{
239 drv->read_otherend_details = read_frontend_details;
240
241 return xenbus_register_driver_common(drv, &xenbus_backend,
242 owner, mod_name);
243}
244EXPORT_SYMBOL_GPL(__xenbus_register_backend);
245
246static int backend_probe_and_watch(struct notifier_block *notifier,
247 unsigned long event,
248 void *data)
249{
250 /* Enumerate devices in xenstore and watch for changes. */
251 xenbus_probe_devices(&xenbus_backend);
252 register_xenbus_watch(&be_watch);
253
254 return NOTIFY_DONE;
255}
256
257static int backend_reclaim_memory(struct device *dev, void *data)
258{
259 const struct xenbus_driver *drv;
260 struct xenbus_device *xdev;
261
262 if (!dev->driver)
263 return 0;
264 drv = to_xenbus_driver(dev->driver);
265 if (drv && drv->reclaim_memory) {
266 xdev = to_xenbus_device(dev);
267 if (down_trylock(&xdev->reclaim_sem))
268 return 0;
269 drv->reclaim_memory(xdev);
270 up(&xdev->reclaim_sem);
271 }
272 return 0;
273}
274
275/*
276 * Returns 0 always because we are using shrinker to only detect memory
277 * pressure.
278 */
279static unsigned long backend_shrink_memory_count(struct shrinker *shrinker,
280 struct shrink_control *sc)
281{
282 bus_for_each_dev(&xenbus_backend.bus, NULL, NULL,
283 backend_reclaim_memory);
284 return 0;
285}
286
287static int __init xenbus_probe_backend_init(void)
288{
289 struct shrinker *backend_memory_shrinker;
290 static struct notifier_block xenstore_notifier = {
291 .notifier_call = backend_probe_and_watch
292 };
293 int err;
294
295 DPRINTK("");
296
297 /* Register ourselves with the kernel bus subsystem */
298 err = bus_register(&xenbus_backend.bus);
299 if (err)
300 return err;
301
302 register_xenstore_notifier(&xenstore_notifier);
303
304 backend_memory_shrinker = shrinker_alloc(0, "xen-backend");
305 if (!backend_memory_shrinker) {
306 pr_warn("shrinker allocation failed\n");
307 return 0;
308 }
309
310 backend_memory_shrinker->count_objects = backend_shrink_memory_count;
311
312 shrinker_register(backend_memory_shrinker);
313
314 return 0;
315}
316subsys_initcall(xenbus_probe_backend_init);
1/******************************************************************************
2 * Talks to Xen Store to figure out what devices we have (backend half).
3 *
4 * Copyright (C) 2005 Rusty Russell, IBM Corporation
5 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
6 * Copyright (C) 2005, 2006 XenSource Ltd
7 * Copyright (C) 2007 Solarflare Communications, Inc.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34#define DPRINTK(fmt, args...) \
35 pr_debug("xenbus_probe (%s:%d) " fmt ".\n", \
36 __func__, __LINE__, ##args)
37
38#include <linux/kernel.h>
39#include <linux/err.h>
40#include <linux/string.h>
41#include <linux/ctype.h>
42#include <linux/fcntl.h>
43#include <linux/mm.h>
44#include <linux/notifier.h>
45#include <linux/export.h>
46
47#include <asm/page.h>
48#include <asm/pgtable.h>
49#include <asm/xen/hypervisor.h>
50#include <asm/hypervisor.h>
51#include <xen/xenbus.h>
52#include <xen/features.h>
53
54#include "xenbus_comms.h"
55#include "xenbus_probe.h"
56
57/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
58static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
59{
60 int domid, err;
61 const char *devid, *type, *frontend;
62 unsigned int typelen;
63
64 type = strchr(nodename, '/');
65 if (!type)
66 return -EINVAL;
67 type++;
68 typelen = strcspn(type, "/");
69 if (!typelen || type[typelen] != '/')
70 return -EINVAL;
71
72 devid = strrchr(nodename, '/') + 1;
73
74 err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
75 "frontend", NULL, &frontend,
76 NULL);
77 if (err)
78 return err;
79 if (strlen(frontend) == 0)
80 err = -ERANGE;
81 if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
82 err = -ENOENT;
83 kfree(frontend);
84
85 if (err)
86 return err;
87
88 if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
89 typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
90 return -ENOSPC;
91 return 0;
92}
93
94static int xenbus_uevent_backend(struct device *dev,
95 struct kobj_uevent_env *env)
96{
97 struct xenbus_device *xdev;
98 struct xenbus_driver *drv;
99 struct xen_bus_type *bus;
100
101 DPRINTK("");
102
103 if (dev == NULL)
104 return -ENODEV;
105
106 xdev = to_xenbus_device(dev);
107 bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
108
109 if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
110 return -ENOMEM;
111
112 /* stuff we want to pass to /sbin/hotplug */
113 if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
114 return -ENOMEM;
115
116 if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
117 return -ENOMEM;
118
119 if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
120 return -ENOMEM;
121
122 if (dev->driver) {
123 drv = to_xenbus_driver(dev->driver);
124 if (drv && drv->uevent)
125 return drv->uevent(xdev, env);
126 }
127
128 return 0;
129}
130
131/* backend/<typename>/<frontend-uuid>/<name> */
132static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
133 const char *dir,
134 const char *type,
135 const char *name)
136{
137 char *nodename;
138 int err;
139
140 nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
141 if (!nodename)
142 return -ENOMEM;
143
144 DPRINTK("%s\n", nodename);
145
146 err = xenbus_probe_node(bus, type, nodename);
147 kfree(nodename);
148 return err;
149}
150
151/* backend/<typename>/<frontend-domid> */
152static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
153 const char *domid)
154{
155 char *nodename;
156 int err = 0;
157 char **dir;
158 unsigned int i, dir_n = 0;
159
160 DPRINTK("");
161
162 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
163 if (!nodename)
164 return -ENOMEM;
165
166 dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
167 if (IS_ERR(dir)) {
168 kfree(nodename);
169 return PTR_ERR(dir);
170 }
171
172 for (i = 0; i < dir_n; i++) {
173 err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
174 if (err)
175 break;
176 }
177 kfree(dir);
178 kfree(nodename);
179 return err;
180}
181
182static void frontend_changed(struct xenbus_watch *watch,
183 const char **vec, unsigned int len)
184{
185 xenbus_otherend_changed(watch, vec, len, 0);
186}
187
188static struct xen_bus_type xenbus_backend = {
189 .root = "backend",
190 .levels = 3, /* backend/type/<frontend>/<id> */
191 .get_bus_id = backend_bus_id,
192 .probe = xenbus_probe_backend,
193 .otherend_changed = frontend_changed,
194 .bus = {
195 .name = "xen-backend",
196 .match = xenbus_match,
197 .uevent = xenbus_uevent_backend,
198 .probe = xenbus_dev_probe,
199 .remove = xenbus_dev_remove,
200 .shutdown = xenbus_dev_shutdown,
201 .dev_attrs = xenbus_dev_attrs,
202 },
203};
204
205static void backend_changed(struct xenbus_watch *watch,
206 const char **vec, unsigned int len)
207{
208 DPRINTK("");
209
210 xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
211}
212
213static struct xenbus_watch be_watch = {
214 .node = "backend",
215 .callback = backend_changed,
216};
217
218static int read_frontend_details(struct xenbus_device *xendev)
219{
220 return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
221}
222
223int xenbus_dev_is_online(struct xenbus_device *dev)
224{
225 int rc, val;
226
227 rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
228 if (rc != 1)
229 val = 0; /* no online node present */
230
231 return val;
232}
233EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
234
235int xenbus_register_backend(struct xenbus_driver *drv)
236{
237 drv->read_otherend_details = read_frontend_details;
238
239 return xenbus_register_driver_common(drv, &xenbus_backend);
240}
241EXPORT_SYMBOL_GPL(xenbus_register_backend);
242
243static int backend_probe_and_watch(struct notifier_block *notifier,
244 unsigned long event,
245 void *data)
246{
247 /* Enumerate devices in xenstore and watch for changes. */
248 xenbus_probe_devices(&xenbus_backend);
249 register_xenbus_watch(&be_watch);
250
251 return NOTIFY_DONE;
252}
253
254static int __init xenbus_probe_backend_init(void)
255{
256 static struct notifier_block xenstore_notifier = {
257 .notifier_call = backend_probe_and_watch
258 };
259 int err;
260
261 DPRINTK("");
262
263 /* Register ourselves with the kernel bus subsystem */
264 err = bus_register(&xenbus_backend.bus);
265 if (err)
266 return err;
267
268 register_xenstore_notifier(&xenstore_notifier);
269
270 return 0;
271}
272subsys_initcall(xenbus_probe_backend_init);