FreeBSD/Linux Kernel Cross Reference
sys/xen/xenbus/xenbusb_back.c

     /******************************************************************************
      * Talks to Xen Store to figure out what devices we have.
      *
      * Copyright (C) 2009, 2010 Spectra Logic Corporation
      * Copyright (C) 2008 Doug Rabson
      * Copyright (C) 2005 Rusty Russell, IBM Corporation
      * Copyright (C) 2005 Mike Wray, Hewlett-Packard
      * Copyright (C) 2005 XenSource Ltd
      * 
     * This file may be 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.
     */
    
    /**
     * \file xenbusb_back.c
     *
     * XenBus management of the NewBus bus containing the backend instances of
     * Xen split devices.
     */
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/sbuf.h>
    #include <sys/sysctl.h>
    #include <sys/syslog.h>
    #include <sys/systm.h>
    #include <sys/sx.h>
    #include <sys/taskqueue.h>
    
    #include <machine/xen/xen-os.h>
    #include <machine/stdarg.h>
    
    #include <xen/gnttab.h>
    #include <xen/xenbus/xenbusvar.h>
    #include <xen/xenbus/xenbusb.h>
    
    /*------------------ Private Device Attachment Functions  --------------------*/
    /**
     * \brief Probe for the existance of the XenBus back bus.
     *
     * \param dev  NewBus device_t for this XenBus back bus instance.
     *
     * \return  Always returns 0 indicating success.
     */
    static int 
    xenbusb_back_probe(device_t dev)
    {
            device_set_desc(dev, "Xen Backend Devices");
    
            return (0);
    }
    
    /**
     * \brief Attach the XenBus back bus.
     *
     * \param dev  NewBus device_t for this XenBus back bus instance.
     *
     * \return  On success, 0. Otherwise an errno value indicating the
     *          type of failure.
     */
    static int
    xenbusb_back_attach(device_t dev)
    {
            struct xenbusb_softc *xbs;
            int error;
    
            xbs = device_get_softc(dev);
            error = xenbusb_attach(dev, "backend", /*id_components*/2);
    
            /*
             * Backend devices operate to serve other domains,
             * so there is no need to hold up boot processing
             * while connections to foreign domains are made.
             */
            mtx_lock(&xbs->xbs_lock);
           if ((xbs->xbs_flags & XBS_ATTACH_CH_ACTIVE) != 0) {
                   xbs->xbs_flags &= ~XBS_ATTACH_CH_ACTIVE;
                   mtx_unlock(&xbs->xbs_lock);
                   config_intrhook_disestablish(&xbs->xbs_attach_ch);
           } else {
                   mtx_unlock(&xbs->xbs_lock);
           }
   
           return (error);
   }
   
   /**
    * \brief Enumerate all devices of the given type on this bus.
    *
    * \param dev   NewBus device_t for this XenBus backend bus instance.
    * \param type  String indicating the device sub-tree (e.g. "vfb", "vif")
    *              to enumerate. 
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    *
    * Devices that are found are entered into the NewBus hierarchy via
    * xenbusb_add_device().  xenbusb_add_device() ignores duplicate detects
    * and ignores duplicate devices, so it can be called unconditionally
    * for any device found in the XenStore.
    *
    * The backend XenStore hierarchy has the following format:
    *
    *     backend/<device type>/<frontend vm id>/<device id>
    *
    */
   static int
   xenbusb_back_enumerate_type(device_t dev, const char *type)
   {
           struct xenbusb_softc *xbs;
           const char **vms;
           u_int vm_idx;
           u_int vm_count;
           int error;
   
           xbs = device_get_softc(dev);
           error = xs_directory(XST_NIL, xbs->xbs_node, type, &vm_count, &vms);
           if (error)
                   return (error);
           for (vm_idx = 0; vm_idx < vm_count; vm_idx++) {
                   struct sbuf *vm_path;
                   const char *vm;
                   const char **devs;
                   u_int dev_idx;
                   u_int dev_count;
   
                   vm = vms[vm_idx];
   
                   vm_path = xs_join(type, vm);
                   error = xs_directory(XST_NIL, xbs->xbs_node, sbuf_data(vm_path),
                       &dev_count, &devs);
                   sbuf_delete(vm_path);
                   if (error)
                           break;
   
                   for (dev_idx = 0; dev_idx < dev_count; dev_idx++) {
                           const char *dev_num;
                           struct sbuf *id;
                           
                           dev_num = devs[dev_idx];
                           id = xs_join(vm, dev_num);
                           xenbusb_add_device(dev, type, sbuf_data(id));
                           sbuf_delete(id);
                   }
                   free(devs, M_XENSTORE);
           }
   
           free(vms, M_XENSTORE);
   
           return (0);
   }
   
   /**
    * \brief Determine and store the XenStore path for the other end of
    *        a split device whose local end is represented by ivars.
    *
    * \param dev    NewBus device_t for this XenBus backend bus instance.
    * \param ivars  Instance variables from the XenBus child device for
    *               which to perform this function.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    *
    * If successful, the xd_otherend_path field of the child's instance
    * variables will be updated.
    *
    */
   static int
   xenbusb_back_get_otherend_node(device_t dev, struct xenbus_device_ivars *ivars)
   {
           char *otherend_path;
           int error;
   
           if (ivars->xd_otherend_path != NULL) {
                   free(ivars->xd_otherend_path, M_XENBUS);
                   ivars->xd_otherend_path = NULL;
           }
                   
           error = xs_gather(XST_NIL, ivars->xd_node,
               "frontend-id", "%i", &ivars->xd_otherend_id,
               "frontend", NULL, &otherend_path,
               NULL);
   
           if (error == 0) {
                   ivars->xd_otherend_path = strdup(otherend_path, M_XENBUS);
                   ivars->xd_otherend_path_len = strlen(otherend_path);
                   free(otherend_path, M_XENSTORE);
           }
           return (error);
   }
   
   /**
    * \brief Backend XenBus method implementing responses to peer state changes.
    * 
    * \param bus       The XenBus bus parent of child.
    * \param child     The XenBus child whose peer stat has changed.
    * \param state     The current state of the peer.
    */
   static void
   xenbusb_back_otherend_changed(device_t bus, device_t child,
                                 enum xenbus_state peer_state)
   {
           /* Perform default processing of state. */
           xenbusb_otherend_changed(bus, child, peer_state);
   
           /*
            * "Online" devices are never fully detached in the
            * newbus sense.  Only the front<->back connection is
            * torn down.  If the front returns to the initialising
            * state after closing a previous connection, signal
            * our willingness to reconnect and that all necessary
            * XenStore data for feature negotiation is present.
            */
           if (peer_state == XenbusStateInitialising
            && xenbus_dev_is_online(child) != 0
            && xenbus_get_state(child) == XenbusStateClosed)
                   xenbus_set_state(child, XenbusStateInitWait);
   }
   
   /**
    * \brief Backend XenBus method implementing responses to local
    *        XenStore changes.
    * 
    * \param bus    The XenBus bus parent of child.
    * \param child  The XenBus child whose peer stat has changed.
    * \param_path   The tree relative sub-path to the modified node.  The empty
    *               string indicates the root of the tree was destroyed.
    */
   static void
   xenbusb_back_localend_changed(device_t bus, device_t child, const char *path)
   {
   
           xenbusb_localend_changed(bus, child, path);
   
           if (strcmp(path, "/state") != 0
            && strcmp(path, "/online") != 0)
                   return;
   
           if (xenbus_get_state(child) != XenbusStateClosed
            || xenbus_dev_is_online(child) != 0)
                   return;
   
           /*
            * Cleanup the hotplug entry in the XenStore if
            * present.  The control domain expects any userland
            * component associated with this device to destroy
            * this node in order to signify it is safe to 
            * teardown the device.  However, not all backends
            * rely on userland components, and those that
            * do should either use a communication channel
            * other than the XenStore, or ensure the hotplug
            * data is already cleaned up.
            *
            * This removal ensures that no matter what path
            * is taken to mark a back-end closed, the control
            * domain will understand that it is closed.
            */
           xs_rm(XST_NIL, xenbus_get_node(child), "hotplug-status");
   }
   
   /*-------------------- Private Device Attachment Data  -----------------------*/
   static device_method_t xenbusb_back_methods[] = { 
           /* Device interface */ 
           DEVMETHOD(device_identify,      xenbusb_identify),
           DEVMETHOD(device_probe,         xenbusb_back_probe), 
           DEVMETHOD(device_attach,        xenbusb_back_attach), 
           DEVMETHOD(device_detach,        bus_generic_detach), 
           DEVMETHOD(device_shutdown,      bus_generic_shutdown), 
           DEVMETHOD(device_suspend,       bus_generic_suspend), 
           DEVMETHOD(device_resume,        xenbusb_resume), 
   
           /* Bus Interface */ 
           DEVMETHOD(bus_print_child,      xenbusb_print_child),
           DEVMETHOD(bus_read_ivar,        xenbusb_read_ivar), 
           DEVMETHOD(bus_write_ivar,       xenbusb_write_ivar), 
           DEVMETHOD(bus_alloc_resource,   bus_generic_alloc_resource),
           DEVMETHOD(bus_release_resource, bus_generic_release_resource),
           DEVMETHOD(bus_activate_resource, bus_generic_activate_resource),
           DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource),
   
           /* XenBus Bus Interface */
           DEVMETHOD(xenbusb_enumerate_type, xenbusb_back_enumerate_type),
           DEVMETHOD(xenbusb_get_otherend_node, xenbusb_back_get_otherend_node),
           DEVMETHOD(xenbusb_otherend_changed, xenbusb_back_otherend_changed),
           DEVMETHOD(xenbusb_localend_changed, xenbusb_back_localend_changed),
           { 0, 0 } 
   }; 
   
   DEFINE_CLASS_0(xenbusb_back, xenbusb_back_driver, xenbusb_back_methods,
                  sizeof(struct xenbusb_softc));
   devclass_t xenbusb_back_devclass; 
   
   DRIVER_MODULE(xenbusb_back, xenstore, xenbusb_back_driver,
                 xenbusb_back_devclass, 0, 0);

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