xenstore_dev.c

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    1 /*
    2  * xenstore_dev.c
    3  * 
    4  * Driver giving user-space access to the kernel's connection to the
    5  * XenStore service.
    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/10.2/sys/xen/xenstore/xenstore_dev.c 279562 2015-03-03 10:11:58Z royger $");
   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 <xen/xen-os.h>
   48 
   49 #include <xen/hypervisor.h>
   50 #include <xen/xenstore/xenstorevar.h>
   51 #include <xen/xenstore/xenstore_internal.h>
   52 
   53 struct xs_dev_transaction {
   54         LIST_ENTRY(xs_dev_transaction) list;
   55         struct xs_transaction handle;
   56 };
   57 
   58 struct xs_dev_data {
   59         /* In-progress transaction. */
   60         LIST_HEAD(xdd_list_head, xs_dev_transaction) transactions;
   61 
   62         /* Partial request. */
   63         unsigned int len;
   64         union {
   65                 struct xsd_sockmsg msg;
   66                 char buffer[PAGE_SIZE];
   67         } u;
   68 
   69         /* Response queue. */
   70 #define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1))
   71         char read_buffer[PAGE_SIZE];
   72         unsigned int read_cons, read_prod;
   73 };
   74 
   75 static int 
   76 xs_dev_read(struct cdev *dev, struct uio *uio, int ioflag)
   77 {
   78         int error;
   79         struct xs_dev_data *u;
   80 
   81         error = devfs_get_cdevpriv((void **)&u);
   82         if (error != 0)
   83                 return (error);
   84 
   85         while (u->read_prod == u->read_cons) {
   86                 error = tsleep(u, PCATCH, "xsdread", hz/10);
   87                 if (error && error != EWOULDBLOCK)
   88                         return (error);
   89         }
   90 
   91         while (uio->uio_resid > 0) {
   92                 if (u->read_cons == u->read_prod)
   93                         break;
   94                 error = uiomove(&u->read_buffer[MASK_READ_IDX(u->read_cons)],
   95                     1, uio);
   96                 if (error)
   97                         return (error);
   98                 u->read_cons++;
   99         }
  100         return (0);
  101 }
  102 
  103 static void
  104 xs_queue_reply(struct xs_dev_data *u, char *data, unsigned int len)
  105 {
  106         int i;
  107 
  108         for (i = 0; i < len; i++, u->read_prod++)
  109                 u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
  110 
  111         KASSERT((u->read_prod - u->read_cons) <= sizeof(u->read_buffer),
  112             ("xenstore reply too big"));
  113 
  114         wakeup(u);
  115 }
  116 
  117 static int 
  118 xs_dev_write(struct cdev *dev, struct uio *uio, int ioflag)
  119 {
  120         int error;
  121         struct xs_dev_data *u;
  122         struct xs_dev_transaction *trans;
  123         void *reply;
  124         int len = uio->uio_resid;
  125 
  126         error = devfs_get_cdevpriv((void **)&u);
  127         if (error != 0)
  128                 return (error);
  129 
  130         if ((len + u->len) > sizeof(u->u.buffer))
  131                 return (EINVAL);
  132 
  133         error = uiomove(u->u.buffer + u->len, len, uio);
  134         if (error)
  135                 return (error);
  136 
  137         u->len += len;
  138         if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
  139                 return (0);
  140 
  141         switch (u->u.msg.type) {
  142         case XS_TRANSACTION_START:
  143         case XS_TRANSACTION_END:
  144         case XS_DIRECTORY:
  145         case XS_READ:
  146         case XS_GET_PERMS:
  147         case XS_RELEASE:
  148         case XS_GET_DOMAIN_PATH:
  149         case XS_WRITE:
  150         case XS_MKDIR:
  151         case XS_RM:
  152         case XS_SET_PERMS:
  153                 error = xs_dev_request_and_reply(&u->u.msg, &reply);
  154                 if (!error) {
  155                         if (u->u.msg.type == XS_TRANSACTION_START) {
  156                                 trans = malloc(sizeof(*trans), M_XENSTORE,
  157                                     M_WAITOK);
  158                                 trans->handle.id = strtoul(reply, NULL, 0);
  159                                 LIST_INSERT_HEAD(&u->transactions, trans, list);
  160                         } else if (u->u.msg.type == XS_TRANSACTION_END) {
  161                                 LIST_FOREACH(trans, &u->transactions, list)
  162                                         if (trans->handle.id == u->u.msg.tx_id)
  163                                                 break;
  164 #if 0 /* XXX does this mean the list is empty? */
  165                                 BUG_ON(&trans->list == &u->transactions);
  166 #endif
  167                                 LIST_REMOVE(trans, list);
  168                                 free(trans, M_XENSTORE);
  169                         }
  170                         xs_queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg));
  171                         xs_queue_reply(u, (char *)reply, u->u.msg.len);
  172                         free(reply, M_XENSTORE);
  173                 }
  174                 break;
  175 
  176         default:
  177                 error = EINVAL;
  178                 break;
  179         }
  180 
  181         if (error == 0)
  182                 u->len = 0;
  183 
  184         return (error);
  185 }
  186 
  187 static void
  188 xs_dev_dtor(void *arg)
  189 {
  190         struct xs_dev_data *u = arg;
  191         struct xs_dev_transaction *trans, *tmp;
  192 
  193         LIST_FOREACH_SAFE(trans, &u->transactions, list, tmp) {
  194                 xs_transaction_end(trans->handle, 1);
  195                 LIST_REMOVE(trans, list);
  196                 free(trans, M_XENSTORE);
  197         }
  198 
  199         free(u, M_XENSTORE);
  200 }
  201 
  202 static int
  203 xs_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
  204 {
  205         struct xs_dev_data *u;
  206         int error;
  207 
  208         u = malloc(sizeof(*u), M_XENSTORE, M_WAITOK|M_ZERO);
  209         LIST_INIT(&u->transactions);
  210         error = devfs_set_cdevpriv(u, xs_dev_dtor);
  211         if (error != 0)
  212                 free(u, M_XENSTORE);
  213 
  214         return (error);
  215 }
  216 
  217 static struct cdevsw xs_dev_cdevsw = {
  218         .d_version = D_VERSION, 
  219         .d_read = xs_dev_read,
  220         .d_write = xs_dev_write,
  221         .d_open = xs_dev_open,
  222         .d_name = "xs_dev",
  223 };
  224 
  225 void
  226 xs_dev_init()
  227 {
  228 
  229         make_dev_credf(MAKEDEV_ETERNAL, &xs_dev_cdevsw, 0, NULL,
  230             UID_ROOT, GID_WHEEL, 0400, "xen/xenstore");
  231 }

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FreeBSD/Linux Kernel Cross Reference sys/xen/xenstore/xenstore_dev.c

FreeBSD/Linux Kernel Cross Reference
sys/xen/xenstore/xenstore_dev.c