blob: 5ebb7233076f75b9ea6395952d3b52ae1cef45d8 [file] [log] [blame]
/******************************************************************************
* Talks to Xen Store to figure out what devices we have (backend half).
*
* Copyright (C) 2005 Rusty Russell, IBM Corporation
* Copyright (C) 2005 Mike Wray, Hewlett-Packard
* Copyright (C) 2005, 2006 XenSource Ltd
* Copyright (C) 2007 Solarflare Communications, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation; or, when distributed
* separately from the Linux kernel or incorporated into other
* software packages, subject to the following license:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#define DPRINTK(fmt, ...) \
pr_debug("(%s:%d) " fmt "\n", \
__func__, __LINE__, ##__VA_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/notifier.h>
#include <linux/export.h>
#include <linux/semaphore.h>
#include <asm/page.h>
#include <asm/xen/hypervisor.h>
#include <asm/hypervisor.h>
#include <xen/xenbus.h>
#include <xen/features.h>
#include "xenbus.h"
/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
{
int domid, err;
const char *devid, *type, *frontend;
unsigned int typelen;
type = strchr(nodename, '/');
if (!type)
return -EINVAL;
type++;
typelen = strcspn(type, "/");
if (!typelen || type[typelen] != '/')
return -EINVAL;
devid = strrchr(nodename, '/') + 1;
err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
"frontend", NULL, &frontend,
NULL);
if (err)
return err;
if (strlen(frontend) == 0)
err = -ERANGE;
if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
err = -ENOENT;
kfree(frontend);
if (err)
return err;
if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
return -ENOSPC;
return 0;
}
static int xenbus_uevent_backend(const struct device *dev,
struct kobj_uevent_env *env)
{
const struct xenbus_device *xdev;
const struct xenbus_driver *drv;
const struct xen_bus_type *bus;
DPRINTK("");
if (dev == NULL)
return -ENODEV;
xdev = to_xenbus_device(dev);
bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
return -ENOMEM;
/* stuff we want to pass to /sbin/hotplug */
if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
return -ENOMEM;
if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
return -ENOMEM;
if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
return -ENOMEM;
if (dev->driver) {
drv = to_xenbus_driver(dev->driver);
if (drv && drv->uevent)
return drv->uevent(xdev, env);
}
return 0;
}
/* backend/<typename>/<frontend-uuid>/<name> */
static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
const char *dir,
const char *type,
const char *name)
{
char *nodename;
int err;
nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
if (!nodename)
return -ENOMEM;
DPRINTK("%s\n", nodename);
err = xenbus_probe_node(bus, type, nodename);
kfree(nodename);
return err;
}
/* backend/<typename>/<frontend-domid> */
static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
const char *domid)
{
char *nodename;
int err = 0;
char **dir;
unsigned int i, dir_n = 0;
DPRINTK("");
nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
if (!nodename)
return -ENOMEM;
dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
if (IS_ERR(dir)) {
kfree(nodename);
return PTR_ERR(dir);
}
for (i = 0; i < dir_n; i++) {
err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
if (err)
break;
}
kfree(dir);
kfree(nodename);
return err;
}
static bool frontend_will_handle(struct xenbus_watch *watch,
const char *path, const char *token)
{
return watch->nr_pending == 0;
}
static void frontend_changed(struct xenbus_watch *watch,
const char *path, const char *token)
{
xenbus_otherend_changed(watch, path, token, 0);
}
static struct xen_bus_type xenbus_backend = {
.root = "backend",
.levels = 3, /* backend/type/<frontend>/<id> */
.get_bus_id = backend_bus_id,
.probe = xenbus_probe_backend,
.otherend_will_handle = frontend_will_handle,
.otherend_changed = frontend_changed,
.bus = {
.name = "xen-backend",
.match = xenbus_match,
.uevent = xenbus_uevent_backend,
.probe = xenbus_dev_probe,
.remove = xenbus_dev_remove,
.dev_groups = xenbus_dev_groups,
},
};
static void backend_changed(struct xenbus_watch *watch,
const char *path, const char *token)
{
DPRINTK("");
xenbus_dev_changed(path, &xenbus_backend);
}
static struct xenbus_watch be_watch = {
.node = "backend",
.callback = backend_changed,
};
static int read_frontend_details(struct xenbus_device *xendev)
{
return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
}
int xenbus_dev_is_online(struct xenbus_device *dev)
{
return !!xenbus_read_unsigned(dev->nodename, "online", 0);
}
EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
int __xenbus_register_backend(struct xenbus_driver *drv, struct module *owner,
const char *mod_name)
{
drv->read_otherend_details = read_frontend_details;
return xenbus_register_driver_common(drv, &xenbus_backend,
owner, mod_name);
}
EXPORT_SYMBOL_GPL(__xenbus_register_backend);
static int backend_probe_and_watch(struct notifier_block *notifier,
unsigned long event,
void *data)
{
/* Enumerate devices in xenstore and watch for changes. */
xenbus_probe_devices(&xenbus_backend);
register_xenbus_watch(&be_watch);
return NOTIFY_DONE;
}
static int backend_reclaim_memory(struct device *dev, void *data)
{
const struct xenbus_driver *drv;
struct xenbus_device *xdev;
if (!dev->driver)
return 0;
drv = to_xenbus_driver(dev->driver);
if (drv && drv->reclaim_memory) {
xdev = to_xenbus_device(dev);
if (down_trylock(&xdev->reclaim_sem))
return 0;
drv->reclaim_memory(xdev);
up(&xdev->reclaim_sem);
}
return 0;
}
/*
* Returns 0 always because we are using shrinker to only detect memory
* pressure.
*/
static unsigned long backend_shrink_memory_count(struct shrinker *shrinker,
struct shrink_control *sc)
{
bus_for_each_dev(&xenbus_backend.bus, NULL, NULL,
backend_reclaim_memory);
return 0;
}
static int __init xenbus_probe_backend_init(void)
{
struct shrinker *backend_memory_shrinker;
static struct notifier_block xenstore_notifier = {
.notifier_call = backend_probe_and_watch
};
int err;
DPRINTK("");
/* Register ourselves with the kernel bus subsystem */
err = bus_register(&xenbus_backend.bus);
if (err)
return err;
register_xenstore_notifier(&xenstore_notifier);
backend_memory_shrinker = shrinker_alloc(0, "xen-backend");
if (!backend_memory_shrinker) {
pr_warn("shrinker allocation failed\n");
return 0;
}
backend_memory_shrinker->count_objects = backend_shrink_memory_count;
shrinker_register(backend_memory_shrinker);
return 0;
}
subsys_initcall(xenbus_probe_backend_init);