diff options
Diffstat (limited to 'drivers/xen/xenbus/xenbus_probe_backend.c')
| -rw-r--r-- | drivers/xen/xenbus/xenbus_probe_backend.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c new file mode 100644 index 000000000..9c09f89d8 --- /dev/null +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -0,0 +1,313 @@ +/****************************************************************************** + * 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(struct device *dev, + struct kobj_uevent_env *env) +{ + struct xenbus_device *xdev; + struct xenbus_driver *drv; + 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 struct shrinker backend_memory_shrinker = { + .count_objects = backend_shrink_memory_count, + .seeks = DEFAULT_SEEKS, +}; + +static int __init xenbus_probe_backend_init(void) +{ + 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); + + if (register_shrinker(&backend_memory_shrinker, "xen-backend")) + pr_warn("shrinker registration failed\n"); + + return 0; +} +subsys_initcall(xenbus_probe_backend_init); |