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![Gustavo A. R. Silva](/assets/img/avatar_default.png)
In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. Addresses-Coverity-ID: 146562 Addresses-Coverity-ID: 146563 Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
502 lines
13 KiB
C
502 lines
13 KiB
C
#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/proc_fs.h>
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#include <linux/notifier.h>
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#include <linux/kthread.h>
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#include <linux/mutex.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/xenbus.h>
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#include <xen/events.h>
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#include <xen/page.h>
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#include <xen/xen.h>
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#include <xen/platform_pci.h>
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#include "xenbus.h"
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/* device/<type>/<id> => <type>-<id> */
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static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
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{
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nodename = strchr(nodename, '/');
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if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
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pr_warn("bad frontend %s\n", nodename);
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return -EINVAL;
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}
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strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
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if (!strchr(bus_id, '/')) {
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pr_warn("bus_id %s no slash\n", bus_id);
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return -EINVAL;
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}
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*strchr(bus_id, '/') = '-';
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return 0;
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}
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/* device/<typename>/<name> */
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static int xenbus_probe_frontend(struct xen_bus_type *bus, 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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/* ignore console/0 */
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if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
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DPRINTK("Ignoring buggy device entry console/0");
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return 0;
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}
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nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
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if (!nodename)
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return -ENOMEM;
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DPRINTK("%s", 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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static int xenbus_uevent_frontend(struct device *_dev,
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struct kobj_uevent_env *env)
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{
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struct xenbus_device *dev = to_xenbus_device(_dev);
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if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
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return -ENOMEM;
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return 0;
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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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xenbus_otherend_changed(watch, path, token, 1);
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}
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static void xenbus_frontend_delayed_resume(struct work_struct *w)
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{
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struct xenbus_device *xdev = container_of(w, struct xenbus_device, work);
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xenbus_dev_resume(&xdev->dev);
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}
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static int xenbus_frontend_dev_resume(struct device *dev)
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{
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/*
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* If xenstored is running in this domain, we cannot access the backend
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* state at the moment, so we need to defer xenbus_dev_resume
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*/
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if (xen_store_domain_type == XS_LOCAL) {
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struct xenbus_device *xdev = to_xenbus_device(dev);
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schedule_work(&xdev->work);
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return 0;
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}
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return xenbus_dev_resume(dev);
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}
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static int xenbus_frontend_dev_probe(struct device *dev)
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{
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if (xen_store_domain_type == XS_LOCAL) {
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struct xenbus_device *xdev = to_xenbus_device(dev);
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INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
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}
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return xenbus_dev_probe(dev);
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}
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static const struct dev_pm_ops xenbus_pm_ops = {
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.suspend = xenbus_dev_suspend,
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.resume = xenbus_frontend_dev_resume,
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.freeze = xenbus_dev_suspend,
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.thaw = xenbus_dev_cancel,
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.restore = xenbus_dev_resume,
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};
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static struct xen_bus_type xenbus_frontend = {
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.root = "device",
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.levels = 2, /* device/type/<id> */
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.get_bus_id = frontend_bus_id,
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.probe = xenbus_probe_frontend,
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.otherend_changed = backend_changed,
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.bus = {
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.name = "xen",
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.match = xenbus_match,
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.uevent = xenbus_uevent_frontend,
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.probe = xenbus_frontend_dev_probe,
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.remove = xenbus_dev_remove,
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.shutdown = xenbus_dev_shutdown,
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.dev_groups = xenbus_dev_groups,
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.pm = &xenbus_pm_ops,
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},
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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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DPRINTK("");
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xenbus_dev_changed(path, &xenbus_frontend);
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}
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/* We watch for devices appearing and vanishing. */
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static struct xenbus_watch fe_watch = {
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.node = "device",
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.callback = frontend_changed,
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};
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static int read_backend_details(struct xenbus_device *xendev)
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{
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return xenbus_read_otherend_details(xendev, "backend-id", "backend");
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}
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static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)
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{
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struct xenbus_device *xendev = to_xenbus_device(dev);
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struct device_driver *drv = data;
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struct xenbus_driver *xendrv;
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/*
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* A device with no driver will never connect. We care only about
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* devices which should currently be in the process of connecting.
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*/
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if (!dev->driver)
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return 0;
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/* Is this search limited to a particular driver? */
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if (drv && (dev->driver != drv))
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return 0;
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if (ignore_nonessential) {
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/* With older QEMU, for PVonHVM guests the guest config files
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* could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
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* which is nonsensical as there is no PV FB (there can be
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* a PVKB) running as HVM guest. */
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if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
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return 0;
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if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
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return 0;
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}
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xendrv = to_xenbus_driver(dev->driver);
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return (xendev->state < XenbusStateConnected ||
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(xendev->state == XenbusStateConnected &&
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xendrv->is_ready && !xendrv->is_ready(xendev)));
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}
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static int essential_device_connecting(struct device *dev, void *data)
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{
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return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
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}
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static int non_essential_device_connecting(struct device *dev, void *data)
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{
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return is_device_connecting(dev, data, false);
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}
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static int exists_essential_connecting_device(struct device_driver *drv)
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{
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return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
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essential_device_connecting);
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}
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static int exists_non_essential_connecting_device(struct device_driver *drv)
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{
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return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
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non_essential_device_connecting);
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}
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static int print_device_status(struct device *dev, void *data)
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{
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struct xenbus_device *xendev = to_xenbus_device(dev);
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struct device_driver *drv = data;
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/* Is this operation limited to a particular driver? */
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if (drv && (dev->driver != drv))
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return 0;
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if (!dev->driver) {
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/* Information only: is this too noisy? */
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pr_info("Device with no driver: %s\n", xendev->nodename);
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} else if (xendev->state < XenbusStateConnected) {
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enum xenbus_state rstate = XenbusStateUnknown;
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if (xendev->otherend)
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rstate = xenbus_read_driver_state(xendev->otherend);
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pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n",
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xendev->nodename, xendev->state, rstate);
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}
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return 0;
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}
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/* We only wait for device setup after most initcalls have run. */
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static int ready_to_wait_for_devices;
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static bool wait_loop(unsigned long start, unsigned int max_delay,
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unsigned int *seconds_waited)
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{
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if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
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if (!*seconds_waited)
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pr_warn("Waiting for devices to initialise: ");
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*seconds_waited += 5;
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pr_cont("%us...", max_delay - *seconds_waited);
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if (*seconds_waited == max_delay) {
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pr_cont("\n");
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return true;
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}
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}
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schedule_timeout_interruptible(HZ/10);
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return false;
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}
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/*
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* On a 5-minute timeout, wait for all devices currently configured. We need
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* to do this to guarantee that the filesystems and / or network devices
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* needed for boot are available, before we can allow the boot to proceed.
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*
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* This needs to be on a late_initcall, to happen after the frontend device
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* drivers have been initialised, but before the root fs is mounted.
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*
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* A possible improvement here would be to have the tools add a per-device
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* flag to the store entry, indicating whether it is needed at boot time.
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* This would allow people who knew what they were doing to accelerate their
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* boot slightly, but of course needs tools or manual intervention to set up
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* those flags correctly.
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*/
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static void wait_for_devices(struct xenbus_driver *xendrv)
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{
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unsigned long start = jiffies;
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struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
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unsigned int seconds_waited = 0;
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if (!ready_to_wait_for_devices || !xen_domain())
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return;
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while (exists_non_essential_connecting_device(drv))
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if (wait_loop(start, 30, &seconds_waited))
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break;
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/* Skips PVKB and PVFB check.*/
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while (exists_essential_connecting_device(drv))
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if (wait_loop(start, 270, &seconds_waited))
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break;
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if (seconds_waited)
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printk("\n");
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bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
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print_device_status);
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}
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int __xenbus_register_frontend(struct xenbus_driver *drv, struct module *owner,
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const char *mod_name)
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{
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int ret;
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drv->read_otherend_details = read_backend_details;
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ret = xenbus_register_driver_common(drv, &xenbus_frontend,
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owner, mod_name);
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if (ret)
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return ret;
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/* If this driver is loaded as a module wait for devices to attach. */
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wait_for_devices(drv);
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return 0;
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}
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EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
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static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
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static int backend_state;
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static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
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const char *path, const char *token)
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{
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if (xenbus_scanf(XBT_NIL, path, "", "%i",
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&backend_state) != 1)
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backend_state = XenbusStateUnknown;
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printk(KERN_DEBUG "XENBUS: backend %s %s\n",
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path, xenbus_strstate(backend_state));
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wake_up(&backend_state_wq);
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}
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static void xenbus_reset_wait_for_backend(char *be, int expected)
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{
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long timeout;
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timeout = wait_event_interruptible_timeout(backend_state_wq,
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backend_state == expected, 5 * HZ);
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if (timeout <= 0)
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pr_info("backend %s timed out\n", be);
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}
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/*
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* Reset frontend if it is in Connected or Closed state.
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* Wait for backend to catch up.
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* State Connected happens during kdump, Closed after kexec.
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*/
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static void xenbus_reset_frontend(char *fe, char *be, int be_state)
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{
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struct xenbus_watch be_watch;
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printk(KERN_DEBUG "XENBUS: backend %s %s\n",
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be, xenbus_strstate(be_state));
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memset(&be_watch, 0, sizeof(be_watch));
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be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
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if (!be_watch.node)
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return;
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be_watch.callback = xenbus_reset_backend_state_changed;
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backend_state = XenbusStateUnknown;
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pr_info("triggering reconnect on %s\n", be);
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register_xenbus_watch(&be_watch);
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/* fall through to forward backend to state XenbusStateInitialising */
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switch (be_state) {
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case XenbusStateConnected:
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xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
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xenbus_reset_wait_for_backend(be, XenbusStateClosing);
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/* fall through */
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case XenbusStateClosing:
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xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
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xenbus_reset_wait_for_backend(be, XenbusStateClosed);
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/* fall through */
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case XenbusStateClosed:
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xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
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xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
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}
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unregister_xenbus_watch(&be_watch);
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pr_info("reconnect done on %s\n", be);
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kfree(be_watch.node);
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}
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static void xenbus_check_frontend(char *class, char *dev)
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{
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int be_state, fe_state, err;
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char *backend, *frontend;
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frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
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if (!frontend)
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return;
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err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
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if (err != 1)
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goto out;
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switch (fe_state) {
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case XenbusStateConnected:
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case XenbusStateClosed:
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printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
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frontend, xenbus_strstate(fe_state));
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backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
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if (!backend || IS_ERR(backend))
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goto out;
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err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
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if (err == 1)
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xenbus_reset_frontend(frontend, backend, be_state);
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kfree(backend);
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break;
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default:
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break;
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}
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out:
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kfree(frontend);
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}
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static void xenbus_reset_state(void)
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{
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char **devclass, **dev;
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int devclass_n, dev_n;
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int i, j;
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devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
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if (IS_ERR(devclass))
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return;
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for (i = 0; i < devclass_n; i++) {
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dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
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if (IS_ERR(dev))
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continue;
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for (j = 0; j < dev_n; j++)
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xenbus_check_frontend(devclass[i], dev[j]);
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kfree(dev);
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}
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kfree(devclass);
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}
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static int frontend_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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/* reset devices in Connected or Closed state */
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if (xen_hvm_domain())
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xenbus_reset_state();
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/* Enumerate devices in xenstore and watch for changes. */
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xenbus_probe_devices(&xenbus_frontend);
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register_xenbus_watch(&fe_watch);
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return NOTIFY_DONE;
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}
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static int __init xenbus_probe_frontend_init(void)
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{
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static struct notifier_block xenstore_notifier = {
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.notifier_call = frontend_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_frontend.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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return 0;
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}
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subsys_initcall(xenbus_probe_frontend_init);
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#ifndef MODULE
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static int __init boot_wait_for_devices(void)
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{
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if (!xen_has_pv_devices())
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return -ENODEV;
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ready_to_wait_for_devices = 1;
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wait_for_devices(NULL);
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return 0;
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}
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late_initcall(boot_wait_for_devices);
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#endif
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MODULE_LICENSE("GPL");
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