xenbus_dev.c

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    1 /*
    2  * xenbus_dev.c
    3  * 
    4  * Driver giving user-space access to the kernel's xenbus connection
    5  * to xenstore.
    6  * 
    7  * Copyright (c) 2005, Christian Limpach
    8  * Copyright (c) 2005, Rusty Russell, IBM Corporation
    9  * 
   10  * This file may be distributed separately from the Linux kernel, or
   11  * incorporated into other software packages, subject to the following license:
   12  * 
   13  * Permission is hereby granted, free of charge, to any person obtaining a copy
   14  * of this source file (the "Software"), to deal in the Software without
   15  * restriction, including without limitation the rights to use, copy, modify,
   16  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
   17  * and to permit persons to whom the Software is furnished to do so, subject to
   18  * the following conditions:
   19  * 
   20  * The above copyright notice and this permission notice shall be included in
   21  * all copies or substantial portions of the Software.
   22  * 
   23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   24  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   25  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   26  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   27  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   28  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   29  * IN THE SOFTWARE.
   30  */
   31 
   32 
   33 #include <sys/cdefs.h>
   34 __FBSDID("$FreeBSD: releng/8.0/sys/xen/xenbus/xenbus_dev.c 186557 2008-12-29 06:31:03Z kmacy $");
   35 
   36 #include <sys/types.h>
   37 #include <sys/cdefs.h>
   38 #include <sys/errno.h>
   39 #include <sys/uio.h>
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/proc.h>
   43 #include <sys/kernel.h>
   44 #include <sys/malloc.h>
   45 #include <sys/conf.h>
   46 
   47 #include <machine/xen/xen-os.h>
   48 #include <xen/hypervisor.h>
   49 #include <xen/xenbus/xenbusvar.h>
   50 #include <xen/xenbus/xenbus_comms.h>
   51 
   52 struct xenbus_dev_transaction {
   53         LIST_ENTRY(xenbus_dev_transaction) list;
   54         struct xenbus_transaction handle;
   55 };
   56 
   57 struct xenbus_dev_data {
   58         /* In-progress transaction. */
   59         LIST_HEAD(xdd_list_head, xenbus_dev_transaction) transactions;
   60 
   61         /* Partial request. */
   62         unsigned int len;
   63         union {
   64                 struct xsd_sockmsg msg;
   65                 char buffer[PAGE_SIZE];
   66         } u;
   67 
   68         /* Response queue. */
   69 #define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1))
   70         char read_buffer[PAGE_SIZE];
   71         unsigned int read_cons, read_prod;
   72 };
   73 
   74 static int 
   75 xenbus_dev_read(struct cdev *dev, struct uio *uio, int ioflag)
   76 {
   77         int error;
   78         struct xenbus_dev_data *u = dev->si_drv1;
   79 
   80         while (u->read_prod == u->read_cons) {
   81                 error = tsleep(u, PCATCH, "xbdread", hz/10);
   82                 if (error && error != EWOULDBLOCK)
   83                         return (error);
   84         }
   85 
   86         while (uio->uio_resid > 0) {
   87                 if (u->read_cons == u->read_prod)
   88                         break;
   89                 error = uiomove(&u->read_buffer[MASK_READ_IDX(u->read_cons)],
   90                     1, uio);
   91                 if (error)
   92                         return (error);
   93                 u->read_cons++;
   94         }
   95         return (0);
   96 }
   97 
   98 static void
   99 queue_reply(struct xenbus_dev_data *u, char *data, unsigned int len)
  100 {
  101         int i;
  102 
  103         for (i = 0; i < len; i++, u->read_prod++)
  104                 u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
  105 
  106         KASSERT((u->read_prod - u->read_cons) <= sizeof(u->read_buffer),
  107             ("xenstore reply too big"));
  108 
  109         wakeup(u);
  110 }
  111 
  112 static int 
  113 xenbus_dev_write(struct cdev *dev, struct uio *uio, int ioflag)
  114 {
  115         int error;
  116         struct xenbus_dev_data *u = dev->si_drv1;
  117         struct xenbus_dev_transaction *trans;
  118         void *reply;
  119         int len = uio->uio_resid;
  120 
  121         if ((len + u->len) > sizeof(u->u.buffer))
  122                 return (EINVAL);
  123 
  124         error = uiomove(u->u.buffer + u->len, len, uio);
  125         if (error)
  126                 return (error);
  127 
  128         u->len += len;
  129         if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
  130                 return (0);
  131 
  132         switch (u->u.msg.type) {
  133         case XS_TRANSACTION_START:
  134         case XS_TRANSACTION_END:
  135         case XS_DIRECTORY:
  136         case XS_READ:
  137         case XS_GET_PERMS:
  138         case XS_RELEASE:
  139         case XS_GET_DOMAIN_PATH:
  140         case XS_WRITE:
  141         case XS_MKDIR:
  142         case XS_RM:
  143         case XS_SET_PERMS:
  144                 error = xenbus_dev_request_and_reply(&u->u.msg, &reply);
  145                 if (!error) {
  146                         if (u->u.msg.type == XS_TRANSACTION_START) {
  147                                 trans = malloc(sizeof(*trans), M_DEVBUF,
  148                                     M_WAITOK);
  149                                 trans->handle.id = strtoul(reply, NULL, 0);
  150                                 LIST_INSERT_HEAD(&u->transactions, trans, list);
  151                         } else if (u->u.msg.type == XS_TRANSACTION_END) {
  152                                 LIST_FOREACH(trans, &u->transactions, list)
  153                                         if (trans->handle.id == u->u.msg.tx_id)
  154                                                 break;
  155 #if 0 /* XXX does this mean the list is empty? */
  156                                 BUG_ON(&trans->list == &u->transactions);
  157 #endif
  158                                 LIST_REMOVE(trans, list);
  159                                 free(trans, M_DEVBUF);
  160                         }
  161                         queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg));
  162                         queue_reply(u, (char *)reply, u->u.msg.len);
  163                         free(reply, M_DEVBUF);
  164                 }
  165                 break;
  166 
  167         default:
  168                 error = EINVAL;
  169                 break;
  170         }
  171 
  172         if (error == 0)
  173                 u->len = 0;
  174 
  175         return (error);
  176 }
  177 
  178 static int
  179 xenbus_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
  180 {
  181         struct xenbus_dev_data *u;
  182 
  183         if (xen_store_evtchn == 0)
  184                 return (ENOENT);
  185 #if 0 /* XXX figure out if equiv needed */
  186         nonseekable_open(inode, filp);
  187 #endif
  188         u = malloc(sizeof(*u), M_DEVBUF, M_WAITOK|M_ZERO);
  189         LIST_INIT(&u->transactions);
  190         dev->si_drv1 = u;
  191 
  192         return (0);
  193 }
  194 
  195 static int
  196 xenbus_dev_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
  197 {
  198         struct xenbus_dev_data *u = dev->si_drv1;
  199         struct xenbus_dev_transaction *trans, *tmp;
  200 
  201         LIST_FOREACH_SAFE(trans, &u->transactions, list, tmp) {
  202                 xenbus_transaction_end(trans->handle, 1);
  203                 LIST_REMOVE(trans, list);
  204                 free(trans, M_DEVBUF);
  205         }
  206 
  207         free(u, M_DEVBUF);
  208         return (0);
  209 }
  210 
  211 static struct cdevsw xenbus_dev_cdevsw = {
  212         .d_version = D_VERSION, 
  213         .d_read = xenbus_dev_read,
  214         .d_write = xenbus_dev_write,
  215         .d_open = xenbus_dev_open,
  216         .d_close = xenbus_dev_close,
  217         .d_name = "xenbus_dev",
  218 };
  219 
  220 static int
  221 xenbus_dev_sysinit(void)
  222 {
  223         make_dev(&xenbus_dev_cdevsw, 0, UID_ROOT, GID_WHEEL, 0400,
  224             "xen/xenbus");
  225 
  226         return (0);
  227 }
  228 SYSINIT(xenbus_dev_sysinit, SI_SUB_DRIVERS, SI_ORDER_MIDDLE,
  229     xenbus_dev_sysinit, NULL);

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

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