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path: root/drivers/xen/xenbus/xenbus_probe_frontend.c
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Diffstat (limited to 'drivers/xen/xenbus/xenbus_probe_frontend.c')
-rw-r--r--drivers/xen/xenbus/xenbus_probe_frontend.c294
1 files changed, 294 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
new file mode 100644
index 000000000000..5bcc2d6cf129
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -0,0 +1,294 @@
1#define DPRINTK(fmt, args...) \
2 pr_debug("xenbus_probe (%s:%d) " fmt ".\n", \
3 __func__, __LINE__, ##args)
4
5#include <linux/kernel.h>
6#include <linux/err.h>
7#include <linux/string.h>
8#include <linux/ctype.h>
9#include <linux/fcntl.h>
10#include <linux/mm.h>
11#include <linux/proc_fs.h>
12#include <linux/notifier.h>
13#include <linux/kthread.h>
14#include <linux/mutex.h>
15#include <linux/io.h>
16
17#include <asm/page.h>
18#include <asm/pgtable.h>
19#include <asm/xen/hypervisor.h>
20#include <xen/xenbus.h>
21#include <xen/events.h>
22#include <xen/page.h>
23
24#include <xen/platform_pci.h>
25
26#include "xenbus_comms.h"
27#include "xenbus_probe.h"
28
29
30/* device/<type>/<id> => <type>-<id> */
31static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
32{
33 nodename = strchr(nodename, '/');
34 if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
35 printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
36 return -EINVAL;
37 }
38
39 strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
40 if (!strchr(bus_id, '/')) {
41 printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
42 return -EINVAL;
43 }
44 *strchr(bus_id, '/') = '-';
45 return 0;
46}
47
48/* device/<typename>/<name> */
49static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
50 const char *name)
51{
52 char *nodename;
53 int err;
54
55 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
56 if (!nodename)
57 return -ENOMEM;
58
59 DPRINTK("%s", nodename);
60
61 err = xenbus_probe_node(bus, type, nodename);
62 kfree(nodename);
63 return err;
64}
65
66static int xenbus_uevent_frontend(struct device *_dev,
67 struct kobj_uevent_env *env)
68{
69 struct xenbus_device *dev = to_xenbus_device(_dev);
70
71 if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
72 return -ENOMEM;
73
74 return 0;
75}
76
77
78static void backend_changed(struct xenbus_watch *watch,
79 const char **vec, unsigned int len)
80{
81 xenbus_otherend_changed(watch, vec, len, 1);
82}
83
84static struct device_attribute xenbus_frontend_dev_attrs[] = {
85 __ATTR_NULL
86};
87
88static struct xen_bus_type xenbus_frontend = {
89 .root = "device",
90 .levels = 2, /* device/type/<id> */
91 .get_bus_id = frontend_bus_id,
92 .probe = xenbus_probe_frontend,
93 .otherend_changed = backend_changed,
94 .bus = {
95 .name = "xen",
96 .match = xenbus_match,
97 .uevent = xenbus_uevent_frontend,
98 .probe = xenbus_dev_probe,
99 .remove = xenbus_dev_remove,
100 .shutdown = xenbus_dev_shutdown,
101 .dev_attrs = xenbus_frontend_dev_attrs,
102
103 .suspend = xenbus_dev_suspend,
104 .resume = xenbus_dev_resume,
105 },
106};
107
108static void frontend_changed(struct xenbus_watch *watch,
109 const char **vec, unsigned int len)
110{
111 DPRINTK("");
112
113 xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
114}
115
116
117/* We watch for devices appearing and vanishing. */
118static struct xenbus_watch fe_watch = {
119 .node = "device",
120 .callback = frontend_changed,
121};
122
123static int read_backend_details(struct xenbus_device *xendev)
124{
125 return xenbus_read_otherend_details(xendev, "backend-id", "backend");
126}
127
128static int is_device_connecting(struct device *dev, void *data)
129{
130 struct xenbus_device *xendev = to_xenbus_device(dev);
131 struct device_driver *drv = data;
132 struct xenbus_driver *xendrv;
133
134 /*
135 * A device with no driver will never connect. We care only about
136 * devices which should currently be in the process of connecting.
137 */
138 if (!dev->driver)
139 return 0;
140
141 /* Is this search limited to a particular driver? */
142 if (drv && (dev->driver != drv))
143 return 0;
144
145 xendrv = to_xenbus_driver(dev->driver);
146 return (xendev->state < XenbusStateConnected ||
147 (xendev->state == XenbusStateConnected &&
148 xendrv->is_ready && !xendrv->is_ready(xendev)));
149}
150
151static int exists_connecting_device(struct device_driver *drv)
152{
153 return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
154 is_device_connecting);
155}
156
157static int print_device_status(struct device *dev, void *data)
158{
159 struct xenbus_device *xendev = to_xenbus_device(dev);
160 struct device_driver *drv = data;
161
162 /* Is this operation limited to a particular driver? */
163 if (drv && (dev->driver != drv))
164 return 0;
165
166 if (!dev->driver) {
167 /* Information only: is this too noisy? */
168 printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
169 xendev->nodename);
170 } else if (xendev->state < XenbusStateConnected) {
171 enum xenbus_state rstate = XenbusStateUnknown;
172 if (xendev->otherend)
173 rstate = xenbus_read_driver_state(xendev->otherend);
174 printk(KERN_WARNING "XENBUS: Timeout connecting "
175 "to device: %s (local state %d, remote state %d)\n",
176 xendev->nodename, xendev->state, rstate);
177 }
178
179 return 0;
180}
181
182/* We only wait for device setup after most initcalls have run. */
183static int ready_to_wait_for_devices;
184
185/*
186 * On a 5-minute timeout, wait for all devices currently configured. We need
187 * to do this to guarantee that the filesystems and / or network devices
188 * needed for boot are available, before we can allow the boot to proceed.
189 *
190 * This needs to be on a late_initcall, to happen after the frontend device
191 * drivers have been initialised, but before the root fs is mounted.
192 *
193 * A possible improvement here would be to have the tools add a per-device
194 * flag to the store entry, indicating whether it is needed at boot time.
195 * This would allow people who knew what they were doing to accelerate their
196 * boot slightly, but of course needs tools or manual intervention to set up
197 * those flags correctly.
198 */
199static void wait_for_devices(struct xenbus_driver *xendrv)
200{
201 unsigned long start = jiffies;
202 struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
203 unsigned int seconds_waited = 0;
204
205 if (!ready_to_wait_for_devices || !xen_domain())
206 return;
207
208 while (exists_connecting_device(drv)) {
209 if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
210 if (!seconds_waited)
211 printk(KERN_WARNING "XENBUS: Waiting for "
212 "devices to initialise: ");
213 seconds_waited += 5;
214 printk("%us...", 300 - seconds_waited);
215 if (seconds_waited == 300)
216 break;
217 }
218
219 schedule_timeout_interruptible(HZ/10);
220 }
221
222 if (seconds_waited)
223 printk("\n");
224
225 bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
226 print_device_status);
227}
228
229int __xenbus_register_frontend(struct xenbus_driver *drv,
230 struct module *owner, const char *mod_name)
231{
232 int ret;
233
234 drv->read_otherend_details = read_backend_details;
235
236 ret = xenbus_register_driver_common(drv, &xenbus_frontend,
237 owner, mod_name);
238 if (ret)
239 return ret;
240
241 /* If this driver is loaded as a module wait for devices to attach. */
242 wait_for_devices(drv);
243
244 return 0;
245}
246EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
247
248static int frontend_probe_and_watch(struct notifier_block *notifier,
249 unsigned long event,
250 void *data)
251{
252 /* Enumerate devices in xenstore and watch for changes. */
253 xenbus_probe_devices(&xenbus_frontend);
254 register_xenbus_watch(&fe_watch);
255
256 return NOTIFY_DONE;
257}
258
259
260static int __init xenbus_probe_frontend_init(void)
261{
262 static struct notifier_block xenstore_notifier = {
263 .notifier_call = frontend_probe_and_watch
264 };
265 int err;
266
267 DPRINTK("");
268
269 /* Register ourselves with the kernel bus subsystem */
270 err = bus_register(&xenbus_frontend.bus);
271 if (err)
272 return err;
273
274 register_xenstore_notifier(&xenstore_notifier);
275
276 return 0;
277}
278subsys_initcall(xenbus_probe_frontend_init);
279
280#ifndef MODULE
281static int __init boot_wait_for_devices(void)
282{
283 if (xen_hvm_domain() && !xen_platform_pci_unplug)
284 return -ENODEV;
285
286 ready_to_wait_for_devices = 1;
287 wait_for_devices(NULL);
288 return 0;
289}
290
291late_initcall(boot_wait_for_devices);
292#endif
293
294MODULE_LICENSE("GPL");