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