xen: separate out frontend xenbus
Impact: refactor
Make a distinct frontend xenbus, in preparation for adding a backend xenbus.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
[corresponds to 2fd433a4188f in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git
with adjustments to reflect changes in the code which is moved]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
new file mode 100644
index 0000000..04c4f01
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -0,0 +1,275 @@
+#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 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,
+ .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 __init xenbus_probe_frontend_init(void)
+{
+ int err;
+
+ DPRINTK("");
+
+ /* Register ourselves with the kernel bus subsystem */
+ err = bus_register(&xenbus_frontend.bus);
+ if (err) {
+ printk(KERN_CRIT "%s didn't register bus!\n", __func__);
+ return err;
+ }
+ printk(KERN_CRIT "%s bus registered ok\n", __func__);
+
+ if (!xen_initial_domain()) {
+ /* Enumerate devices in xenstore and watch for changes. */
+ xenbus_probe_devices(&xenbus_frontend);
+ printk(KERN_CRIT "%s devices probed ok\n", __func__);
+ register_xenbus_watch(&fe_watch);
+ printk(KERN_CRIT "%s watch add ok ok\n", __func__);
+ printk(KERN_CRIT "%s all done\n", __func__);
+ }
+
+ return 0;
+}
+
+module_init(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