freebsd-skq/sys/dev/xen/xenstore/xenstore_dev.c
royger 37c8d086a5 xen: fix xenstore dev
Xenstore user-space device has two problems currently:
 - It does not correctly handle concurrent clients, because it's storing
   each client data in dev->si_drv1.
 - It does not correctly free this data when the client closes the device.

In order to solve both of this issues store the per-client data using
cdevpriv, which also comes with a hook in order to perform the necessary
cleanup on device close.

While there also make the device eternal.

Sponsored by: Citrix Systems R&D
Reported and Tested by: thompsa
MFC after: 2 weeks
2015-02-16 09:53:43 +00:00

294 lines
7.1 KiB
C

/*
* xenstore_dev.c
*
* Driver giving user-space access to the kernel's connection to the
* XenStore service.
*
* Copyright (c) 2005, Christian Limpach
* Copyright (c) 2005, Rusty Russell, IBM Corporation
*
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/cdefs.h>
#include <sys/errno.h>
#include <sys/uio.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/conf.h>
#include <sys/module.h>
#include <xen/xen-os.h>
#include <xen/hypervisor.h>
#include <xen/xenstore/xenstorevar.h>
#include <xen/xenstore/xenstore_internal.h>
struct xs_dev_transaction {
LIST_ENTRY(xs_dev_transaction) list;
struct xs_transaction handle;
};
struct xs_dev_data {
/* In-progress transaction. */
LIST_HEAD(xdd_list_head, xs_dev_transaction) transactions;
/* Partial request. */
unsigned int len;
union {
struct xsd_sockmsg msg;
char buffer[PAGE_SIZE];
} u;
/* Response queue. */
#define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1))
char read_buffer[PAGE_SIZE];
unsigned int read_cons, read_prod;
};
static int
xs_dev_read(struct cdev *dev, struct uio *uio, int ioflag)
{
int error;
struct xs_dev_data *u;
error = devfs_get_cdevpriv((void **)&u);
if (error != 0)
return (error);
while (u->read_prod == u->read_cons) {
error = tsleep(u, PCATCH, "xsdread", hz/10);
if (error && error != EWOULDBLOCK)
return (error);
}
while (uio->uio_resid > 0) {
if (u->read_cons == u->read_prod)
break;
error = uiomove(&u->read_buffer[MASK_READ_IDX(u->read_cons)],
1, uio);
if (error)
return (error);
u->read_cons++;
}
return (0);
}
static void
xs_queue_reply(struct xs_dev_data *u, char *data, unsigned int len)
{
int i;
for (i = 0; i < len; i++, u->read_prod++)
u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
KASSERT((u->read_prod - u->read_cons) <= sizeof(u->read_buffer),
("xenstore reply too big"));
wakeup(u);
}
static int
xs_dev_write(struct cdev *dev, struct uio *uio, int ioflag)
{
int error;
struct xs_dev_data *u;
struct xs_dev_transaction *trans;
void *reply;
int len = uio->uio_resid;
error = devfs_get_cdevpriv((void **)&u);
if (error != 0)
return (error);
if ((len + u->len) > sizeof(u->u.buffer))
return (EINVAL);
error = uiomove(u->u.buffer + u->len, len, uio);
if (error)
return (error);
u->len += len;
if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
return (0);
switch (u->u.msg.type) {
case XS_TRANSACTION_START:
case XS_TRANSACTION_END:
case XS_DIRECTORY:
case XS_READ:
case XS_GET_PERMS:
case XS_RELEASE:
case XS_GET_DOMAIN_PATH:
case XS_WRITE:
case XS_MKDIR:
case XS_RM:
case XS_SET_PERMS:
error = xs_dev_request_and_reply(&u->u.msg, &reply);
if (!error) {
if (u->u.msg.type == XS_TRANSACTION_START) {
trans = malloc(sizeof(*trans), M_XENSTORE,
M_WAITOK);
trans->handle.id = strtoul(reply, NULL, 0);
LIST_INSERT_HEAD(&u->transactions, trans, list);
} else if (u->u.msg.type == XS_TRANSACTION_END) {
LIST_FOREACH(trans, &u->transactions, list)
if (trans->handle.id == u->u.msg.tx_id)
break;
#if 0 /* XXX does this mean the list is empty? */
BUG_ON(&trans->list == &u->transactions);
#endif
LIST_REMOVE(trans, list);
free(trans, M_XENSTORE);
}
xs_queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg));
xs_queue_reply(u, (char *)reply, u->u.msg.len);
free(reply, M_XENSTORE);
}
break;
default:
error = EINVAL;
break;
}
if (error == 0)
u->len = 0;
return (error);
}
static void
xs_dev_dtor(void *arg)
{
struct xs_dev_data *u = arg;
struct xs_dev_transaction *trans, *tmp;
LIST_FOREACH_SAFE(trans, &u->transactions, list, tmp) {
xs_transaction_end(trans->handle, 1);
LIST_REMOVE(trans, list);
free(trans, M_XENSTORE);
}
free(u, M_XENSTORE);
}
static int
xs_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
struct xs_dev_data *u;
int error;
u = malloc(sizeof(*u), M_XENSTORE, M_WAITOK|M_ZERO);
LIST_INIT(&u->transactions);
error = devfs_set_cdevpriv(u, xs_dev_dtor);
if (error != 0)
free(u, M_XENSTORE);
return (error);
}
static struct cdevsw xs_dev_cdevsw = {
.d_version = D_VERSION,
.d_read = xs_dev_read,
.d_write = xs_dev_write,
.d_open = xs_dev_open,
.d_name = "xs_dev",
};
/*------------------ Private Device Attachment Functions --------------------*/
/**
* \brief Identify instances of this device type in the system.
*
* \param driver The driver performing this identify action.
* \param parent The NewBus parent device for any devices this method adds.
*/
static void
xs_dev_identify(driver_t *driver __unused, device_t parent)
{
/*
* A single device instance for our driver is always present
* in a system operating under Xen.
*/
BUS_ADD_CHILD(parent, 0, driver->name, 0);
}
/**
* \brief Probe for the existance of the Xenstore device
*
* \param dev NewBus device_t for this instance.
*
* \return Always returns 0 indicating success.
*/
static int
xs_dev_probe(device_t dev)
{
device_set_desc(dev, "Xenstore user-space device");
return (0);
}
/**
* \brief Attach the Xenstore device.
*
* \param dev NewBus device_t for this instance.
*
* \return On success, 0. Otherwise an errno value indicating the
* type of failure.
*/
static int
xs_dev_attach(device_t dev)
{
struct cdev *xs_cdev;
xs_cdev = make_dev_credf(MAKEDEV_ETERNAL, &xs_dev_cdevsw, 0, NULL,
UID_ROOT, GID_WHEEL, 0400, "xen/xenstore");
if (xs_cdev == NULL)
return (EINVAL);
return (0);
}
/*-------------------- Private Device Attachment Data -----------------------*/
static device_method_t xs_dev_methods[] = {
/* Device interface */
DEVMETHOD(device_identify, xs_dev_identify),
DEVMETHOD(device_probe, xs_dev_probe),
DEVMETHOD(device_attach, xs_dev_attach),
DEVMETHOD_END
};
DEFINE_CLASS_0(xs_dev, xs_dev_driver, xs_dev_methods, 0);
devclass_t xs_dev_devclass;
DRIVER_MODULE(xs_dev, xenstore, xs_dev_driver, xs_dev_devclass,
NULL, NULL);