linux/drivers/xen/xenbus/xenbus_probe_frontend.c

420 lines
11 KiB
C
Raw Normal View History

#define DPRINTK(fmt, args...) \
pr_debug("xenbus_probe (%s:%d) " fmt ".\n", \
__func__, __LINE__, ##args)
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/notifier.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/module.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/xen/hypervisor.h>
#include <xen/xenbus.h>
#include <xen/events.h>
#include <xen/page.h>
#include <xen/platform_pci.h>
#include "xenbus_comms.h"
#include "xenbus_probe.h"
/* device/<type>/<id> => <type>-<id> */
static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
{
nodename = strchr(nodename, '/');
if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
return -EINVAL;
}
strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
if (!strchr(bus_id, '/')) {
printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
return -EINVAL;
}
*strchr(bus_id, '/') = '-';
return 0;
}
/* device/<typename>/<name> */
static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
const char *name)
{
char *nodename;
int err;
nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
if (!nodename)
return -ENOMEM;
DPRINTK("%s", nodename);
err = xenbus_probe_node(bus, type, nodename);
kfree(nodename);
return err;
}
static int xenbus_uevent_frontend(struct device *_dev,
struct kobj_uevent_env *env)
{
struct xenbus_device *dev = to_xenbus_device(_dev);
if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
return -ENOMEM;
return 0;
}
static void backend_changed(struct xenbus_watch *watch,
const char **vec, unsigned int len)
{
xenbus_otherend_changed(watch, vec, len, 1);
}
static const struct dev_pm_ops xenbus_pm_ops = {
.suspend = xenbus_dev_suspend,
.resume = xenbus_dev_resume,
.freeze = xenbus_dev_suspend,
.thaw = xenbus_dev_cancel,
.restore = xenbus_dev_resume,
};
static struct xen_bus_type xenbus_frontend = {
.root = "device",
.levels = 2, /* device/type/<id> */
.get_bus_id = frontend_bus_id,
.probe = xenbus_probe_frontend,
.otherend_changed = backend_changed,
.bus = {
.name = "xen",
.match = xenbus_match,
.uevent = xenbus_uevent_frontend,
.probe = xenbus_dev_probe,
.remove = xenbus_dev_remove,
.shutdown = xenbus_dev_shutdown,
.dev_attrs = xenbus_dev_attrs,
.pm = &xenbus_pm_ops,
},
};
static void frontend_changed(struct xenbus_watch *watch,
const char **vec, unsigned int len)
{
DPRINTK("");
xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
}
/* We watch for devices appearing and vanishing. */
static struct xenbus_watch fe_watch = {
.node = "device",
.callback = frontend_changed,
};
static int read_backend_details(struct xenbus_device *xendev)
{
return xenbus_read_otherend_details(xendev, "backend-id", "backend");
}
static int is_device_connecting(struct device *dev, void *data)
{
struct xenbus_device *xendev = to_xenbus_device(dev);
struct device_driver *drv = data;
struct xenbus_driver *xendrv;
/*
* A device with no driver will never connect. We care only about
* devices which should currently be in the process of connecting.
*/
if (!dev->driver)
return 0;
/* Is this search limited to a particular driver? */
if (drv && (dev->driver != drv))
return 0;
xendrv = to_xenbus_driver(dev->driver);
return (xendev->state < XenbusStateConnected ||
(xendev->state == XenbusStateConnected &&
xendrv->is_ready && !xendrv->is_ready(xendev)));
}
static int exists_connecting_device(struct device_driver *drv)
{
return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
is_device_connecting);
}
static int print_device_status(struct device *dev, void *data)
{
struct xenbus_device *xendev = to_xenbus_device(dev);
struct device_driver *drv = data;
/* Is this operation limited to a particular driver? */
if (drv && (dev->driver != drv))
return 0;
if (!dev->driver) {
/* Information only: is this too noisy? */
printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
xendev->nodename);
} else if (xendev->state < XenbusStateConnected) {
enum xenbus_state rstate = XenbusStateUnknown;
if (xendev->otherend)
rstate = xenbus_read_driver_state(xendev->otherend);
printk(KERN_WARNING "XENBUS: Timeout connecting "
"to device: %s (local state %d, remote state %d)\n",
xendev->nodename, xendev->state, rstate);
}
return 0;
}
/* We only wait for device setup after most initcalls have run. */
static int ready_to_wait_for_devices;
/*
* On a 5-minute timeout, wait for all devices currently configured. We need
* to do this to guarantee that the filesystems and / or network devices
* needed for boot are available, before we can allow the boot to proceed.
*
* This needs to be on a late_initcall, to happen after the frontend device
* drivers have been initialised, but before the root fs is mounted.
*
* A possible improvement here would be to have the tools add a per-device
* flag to the store entry, indicating whether it is needed at boot time.
* This would allow people who knew what they were doing to accelerate their
* boot slightly, but of course needs tools or manual intervention to set up
* those flags correctly.
*/
static void wait_for_devices(struct xenbus_driver *xendrv)
{
unsigned long start = jiffies;
struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
unsigned int seconds_waited = 0;
if (!ready_to_wait_for_devices || !xen_domain())
return;
while (exists_connecting_device(drv)) {
if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
if (!seconds_waited)
printk(KERN_WARNING "XENBUS: Waiting for "
"devices to initialise: ");
seconds_waited += 5;
printk("%us...", 300 - seconds_waited);
if (seconds_waited == 300)
break;
}
schedule_timeout_interruptible(HZ/10);
}
if (seconds_waited)
printk("\n");
bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
print_device_status);
}
int __xenbus_register_frontend(struct xenbus_driver *drv,
struct module *owner, const char *mod_name)
{
int ret;
drv->read_otherend_details = read_backend_details;
ret = xenbus_register_driver_common(drv, &xenbus_frontend,
owner, mod_name);
if (ret)
return ret;
/* If this driver is loaded as a module wait for devices to attach. */
wait_for_devices(drv);
return 0;
}
EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
static int backend_state;
static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
const char **v, unsigned int l)
{
xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
printk(KERN_DEBUG "XENBUS: backend %s %s\n",
v[XS_WATCH_PATH], xenbus_strstate(backend_state));
wake_up(&backend_state_wq);
}
static void xenbus_reset_wait_for_backend(char *be, int expected)
{
long timeout;
timeout = wait_event_interruptible_timeout(backend_state_wq,
backend_state == expected, 5 * HZ);
if (timeout <= 0)
printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
}
/*
* Reset frontend if it is in Connected or Closed state.
* Wait for backend to catch up.
* State Connected happens during kdump, Closed after kexec.
*/
static void xenbus_reset_frontend(char *fe, char *be, int be_state)
{
struct xenbus_watch be_watch;
printk(KERN_DEBUG "XENBUS: backend %s %s\n",
be, xenbus_strstate(be_state));
memset(&be_watch, 0, sizeof(be_watch));
be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
if (!be_watch.node)
return;
be_watch.callback = xenbus_reset_backend_state_changed;
backend_state = XenbusStateUnknown;
printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
register_xenbus_watch(&be_watch);
/* fall through to forward backend to state XenbusStateInitialising */
switch (be_state) {
case XenbusStateConnected:
xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
xenbus_reset_wait_for_backend(be, XenbusStateClosing);
case XenbusStateClosing:
xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
xenbus_reset_wait_for_backend(be, XenbusStateClosed);
case XenbusStateClosed:
xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
}
unregister_xenbus_watch(&be_watch);
printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
kfree(be_watch.node);
}
static void xenbus_check_frontend(char *class, char *dev)
{
int be_state, fe_state, err;
char *backend, *frontend;
frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
if (!frontend)
return;
err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
if (err != 1)
goto out;
switch (fe_state) {
case XenbusStateConnected:
case XenbusStateClosed:
printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
frontend, xenbus_strstate(fe_state));
backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
if (!backend || IS_ERR(backend))
goto out;
err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
if (err == 1)
xenbus_reset_frontend(frontend, backend, be_state);
kfree(backend);
break;
default:
break;
}
out:
kfree(frontend);
}
static void xenbus_reset_state(void)
{
char **devclass, **dev;
int devclass_n, dev_n;
int i, j;
devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
if (IS_ERR(devclass))
return;
for (i = 0; i < devclass_n; i++) {
dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
if (IS_ERR(dev))
continue;
for (j = 0; j < dev_n; j++)
xenbus_check_frontend(devclass[i], dev[j]);
kfree(dev);
}
kfree(devclass);
}
static int frontend_probe_and_watch(struct notifier_block *notifier,
unsigned long event,
void *data)
{
/* reset devices in Connected or Closed state */
if (xen_hvm_domain())
xenbus_reset_state();
/* Enumerate devices in xenstore and watch for changes. */
xenbus_probe_devices(&xenbus_frontend);
register_xenbus_watch(&fe_watch);
return NOTIFY_DONE;
}
static int __init xenbus_probe_frontend_init(void)
{
static struct notifier_block xenstore_notifier = {
.notifier_call = frontend_probe_and_watch
};
int err;
DPRINTK("");
/* Register ourselves with the kernel bus subsystem */
err = bus_register(&xenbus_frontend.bus);
if (err)
return err;
register_xenstore_notifier(&xenstore_notifier);
return 0;
}
subsys_initcall(xenbus_probe_frontend_init);
#ifndef MODULE
static int __init boot_wait_for_devices(void)
{
if (xen_hvm_domain() && !xen_platform_pci_unplug)
return -ENODEV;
ready_to_wait_for_devices = 1;
wait_for_devices(NULL);
return 0;
}
late_initcall(boot_wait_for_devices);
#endif
MODULE_LICENSE("GPL");