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 @@
+#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 <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 struct device_attribute xenbus_frontend_dev_attrs[] = {
+        __ATTR_NULL
+};
+
+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_frontend_dev_attrs,
+
+                .suspend        = xenbus_dev_suspend,
+                .resume         = xenbus_dev_resume,
+        },
+};
+
+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 int frontend_probe_and_watch(struct notifier_block *notifier,
+                                   unsigned long event,
+                                   void *data)
+{
+        /* 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");