/* $NetBSD: xenbus_xs.c,v 1.23 2012/11/28 16:26:59 royger Exp $ */
/******************************************************************************
* xenbus_xs.c
*
* This is the kernel equivalent of the "xs" library. We don't need everything
* and we use xenbus_comms for communication.
*
* 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>
__KERNEL_RCSID(0, "$NetBSD: xenbus_xs.c,v 1.23 2012/11/28 16:26:59 royger Exp $");
#if 0
#define DPRINTK(fmt, args...) \
printf("xenbus_xs (%s:%d) " fmt ".\n", __func__, __LINE__, ##args)
#else
#define DPRINTK(fmt, args...) ((void)0)
#endif
#include <sys/types.h>
#include <sys/null.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/mutex.h>
#include <sys/kthread.h>
#include <xen/xen.h> /* for xendomain_is_dom0() */
#include <xen/xenbus.h>
#include "xenbus_comms.h"
#define streq(a, b) (strcmp((a), (b)) == 0)
struct xs_stored_msg {
SIMPLEQ_ENTRY(xs_stored_msg) msg_next;
struct xsd_sockmsg hdr;
union {
/* Queued replies. */
struct {
char *body;
} reply;
/* Queued watch events. */
struct {
struct xenbus_watch *handle;
char **vec;
unsigned int vec_size;
} watch;
} u;
};
struct xs_handle {
/* A list of replies. Currently only one will ever be outstanding. */
SIMPLEQ_HEAD(, xs_stored_msg) reply_list;
kmutex_t reply_lock;
kcondvar_t reply_cv;
kmutex_t xs_lock; /* serialize access to xenstore */
int suspend_spl;
};
static struct xs_handle xs_state;
/* List of registered watches, and a lock to protect it. */
static SLIST_HEAD(, xenbus_watch) watches;
static kmutex_t watches_lock;
/* List of pending watch callback events, and a lock to protect it. */
static SIMPLEQ_HEAD(, xs_stored_msg) watch_events;
static kmutex_t watch_events_lock;
static kcondvar_t watch_cv;
static int
get_error(const char *errorstring)
{
unsigned int i;
for (i = 0; !streq(errorstring, xsd_errors[i].errstring); i++) {
if (i == (sizeof(xsd_errors) / sizeof(xsd_errors[0]) - 1)) {
printf(
"XENBUS xen store gave: unknown error %s",
errorstring);
return EINVAL;
}
}
return xsd_errors[i].errnum;
}
static void *
read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
{
struct xs_stored_msg *msg;
char *body;
mutex_enter(&xs_state.reply_lock);
while (SIMPLEQ_EMPTY(&xs_state.reply_list)) {
cv_wait(&xs_state.reply_cv, &xs_state.reply_lock);
}
msg = SIMPLEQ_FIRST(&xs_state.reply_list);
SIMPLEQ_REMOVE_HEAD(&xs_state.reply_list, msg_next);
mutex_exit(&xs_state.reply_lock);
*type = msg->hdr.type;
if (len)
*len = msg->hdr.len;
body = msg->u.reply.body;
DPRINTK("read_reply: type %d body %s",
msg->hdr.type, body);
free(msg, M_DEVBUF);
return body;
}
#if 0
/* Emergency write. */
void
xenbus_debug_write(const char *str, unsigned int count)
{
struct xsd_sockmsg msg = { 0 };
msg.type = XS_DEBUG;
msg.len = sizeof("print") + count + 1;
xb_write(&msg, sizeof(msg));
xb_write("print", sizeof("print"));
xb_write(str, count);
xb_write("", 1);
}
#endif
int
xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void**reply)
{
int err = 0, s;
s = spltty();
mutex_enter(&xs_state.xs_lock);
err = xb_write(msg, sizeof(*msg) + msg->len);
if (err) {
msg->type = XS_ERROR;
*reply = NULL;
} else {
*reply = read_reply(&msg->type, &msg->len);
}
mutex_exit(&xs_state.xs_lock);
splx(s);
return err;
}
/* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */
static int
xs_talkv(struct xenbus_transaction *t,
enum xsd_sockmsg_type type,
const struct iovec *iovec,
unsigned int num_vecs,
unsigned int *len,
char **retbuf)
{
struct xsd_sockmsg msg;
unsigned int i;
int err, s;
void *ret;
msg.tx_id = (uint32_t)(unsigned long)t;
msg.req_id = 0;
msg.type = type;
msg.len = 0;
for (i = 0; i < num_vecs; i++)
msg.len += iovec[i].iov_len;
s = spltty();
mutex_enter(&xs_state.xs_lock);
DPRINTK("write msg");
err = xb_write(&msg, sizeof(msg));
DPRINTK("write msg err %d", err);
if (err) {
mutex_exit(&xs_state.xs_lock);
splx(s);
return (err);
}
for (i = 0; i < num_vecs; i++) {
DPRINTK("write iovect");
err = xb_write(iovec[i].iov_base, iovec[i].iov_len);
DPRINTK("write iovect err %d", err);
if (err) {
mutex_exit(&xs_state.xs_lock);
splx(s);
return (err);
}
}
DPRINTK("read");
ret = read_reply(&msg.type, len);
DPRINTK("read done");
mutex_exit(&xs_state.xs_lock);
splx(s);
if (msg.type == XS_ERROR) {
err = get_error(ret);
free(ret, M_DEVBUF);
return (err);
}
KASSERT(msg.type == type);
if (retbuf != NULL)
*retbuf = ret;
else
free(ret, M_DEVBUF);
return 0;
}
/* Simplified version of xs_talkv: single message. */
static int
xs_single(struct xenbus_transaction *t,
enum xsd_sockmsg_type type,
const char *string,
unsigned int *len,
char **ret)
{
struct iovec iovec;
/* xs_talkv only reads iovec */
iovec.iov_base = __UNCONST(string);
iovec.iov_len = strlen(string) + 1;
return xs_talkv(t, type, &iovec, 1, len, ret);
}
static unsigned int
count_strings(const char *strings, unsigned int len)
{
unsigned int num;
const char *p;
for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1)
num++;
return num;
}
/* Return the path to dir with /name appended. Buffer must be kfree()'ed. */
static char *
join(const char *dir, const char *name)
{
char *buffer;
buffer = malloc(strlen(dir) + strlen("/") + strlen(name) + 1,
M_DEVBUF, M_NOWAIT);
if (buffer == NULL)
return NULL;
strcpy(buffer, dir);
if (!streq(name, "")) {
strcat(buffer, "/");
strcat(buffer, name);
}
return buffer;
}
static char **
split(char *strings, unsigned int len, unsigned int *num)
{
char *p, **ret;
/* Count the strings. */
*num = count_strings(strings, len);
/* Transfer to one big alloc for easy freeing. */
ret = malloc(*num * sizeof(char *) + len, M_DEVBUF, M_NOWAIT);
if (!ret) {
free(strings, M_DEVBUF);
return NULL;
}
memcpy(&ret[*num], strings, len);
free(strings, M_DEVBUF);
strings = (char *)&ret[*num];
for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1)
ret[(*num)++] = p;
return ret;
}
int
xenbus_directory(struct xenbus_transaction *t,
const char *dir, const char *node, unsigned int *num,
char ***retbuf)
{
char *strings, *path;
unsigned int len;
int err;
path = join(dir, node);
if (path == NULL)
return ENOMEM;
err = xs_single(t, XS_DIRECTORY, path, &len, &strings);
DPRINTK("xs_single %d %d", err, len);
free(path, M_DEVBUF);
if (err)
return err;
DPRINTK("xs_single strings %s", strings);
*retbuf = split(strings, len, num);
if (*retbuf == NULL)
return ENOMEM;
return 0;
}
/* Check if a path exists. Return 1 if it does. */
int
xenbus_exists(struct xenbus_transaction *t,
const char *dir, const char *node)
{
char **d;
int dir_n, err;
err = xenbus_directory(t, dir, node, &dir_n, &d);
if (err)
return 0;
free(d, M_DEVBUF);
return 1;
}
/* Get the value of a single file.
* Returns a kmalloced value: call free() on it after use.
* len indicates length in bytes.
*/
int
xenbus_read(struct xenbus_transaction *t,
const char *dir, const char *node, unsigned int *len,
char **ret)
{
char *path;
int err;
path = join(dir, node);
if (path == NULL)
return ENOMEM;
err = xs_single(t, XS_READ, path, len, ret);
free(path, M_DEVBUF);
return err;
}
/* Read a node and convert it to unsigned long. */
int
xenbus_read_ul(struct xenbus_transaction *t,
const char *dir, const char *node, unsigned long *val,
int base)
{
char *string, *ep;
int err;
err = xenbus_read(t, dir, node, NULL, &string);
if (err)
return err;
*val = strtoul(string, &ep, base);
if (*ep != '\0') {
free(string, M_DEVBUF);
return EFTYPE;
}
free(string, M_DEVBUF);
return 0;
}
/* Read a node and convert it to unsigned long long. */
int
xenbus_read_ull(struct xenbus_transaction *t,
const char *dir, const char *node, unsigned long long *val,
int base)
{
char *string, *ep;
int err;
err = xenbus_read(t, dir, node, NULL, &string);
if (err)
return err;
*val = strtoull(string, &ep, base);
if (*ep != '\0') {
free(string, M_DEVBUF);
return EFTYPE;
}
free(string, M_DEVBUF);
return 0;
}
/* Write the value of a single file.
* Returns -err on failure.
*/
int
xenbus_write(struct xenbus_transaction *t,
const char *dir, const char *node, const char *string)
{
const char *path;
struct iovec iovec[2];
int ret;
path = join(dir, node);
if (path == NULL)
return ENOMEM;
/* xs_talkv only reads iovec */
iovec[0].iov_base = __UNCONST(path);
iovec[0].iov_len = strlen(path) + 1;
iovec[1].iov_base = __UNCONST(string);
iovec[1].iov_len = strlen(string);
ret = xs_talkv(t, XS_WRITE, iovec, 2, NULL, NULL);
return ret;
}
/* Create a new directory. */
int
xenbus_mkdir(struct xenbus_transaction *t,
const char *dir, const char *node)
{
char *path;
int ret;
path = join(dir, node);
if (path == NULL)
return ENOMEM;
ret = xs_single(t, XS_MKDIR, path, NULL, NULL);
free(path, M_DEVBUF);
return ret;
}
/* Destroy a file or directory (directories must be empty). */
int xenbus_rm(struct xenbus_transaction *t, const char *dir, const char *node)
{
char *path;
int ret;
path = join(dir, node);
if (path == NULL)
return ENOMEM;
ret = xs_single(t, XS_RM, path, NULL, NULL);
free(path, M_DEVBUF);
return ret;
}
/* Start a transaction: changes by others will not be seen during this
* transaction, and changes will not be visible to others until end.
* MUST BE CALLED AT IPL_TTY !
*/
struct xenbus_transaction *
xenbus_transaction_start(void)
{
char *id_str;
unsigned long id, err;
err = xs_single(NULL, XS_TRANSACTION_START, "", NULL, &id_str);
if (err) {
return NULL;
}
id = strtoul(id_str, NULL, 0);
free(id_str, M_DEVBUF);
return (struct xenbus_transaction *)id;
}
/* End a transaction.
* If abandon is true, transaction is discarded instead of committed.
* MUST BE CALLED AT IPL_TTY !
*/
int xenbus_transaction_end(struct xenbus_transaction *t, int abort)
{
char abortstr[2];
int err;
if (abort)
strcpy(abortstr, "F");
else
strcpy(abortstr, "T");
err = xs_single(t, XS_TRANSACTION_END, abortstr, NULL, NULL);
return err;
}
/* Single read and scanf: returns -errno or num scanned. */
int
xenbus_scanf(struct xenbus_transaction *t,
const char *dir, const char *node, const char *fmt, ...)
{
va_list ap;
int ret;
char *val;
ret = xenbus_read(t, dir, node, NULL, &val);
if (ret)
return ret;
va_start(ap, fmt);
//ret = vsscanf(val, fmt, ap);
ret = ENXIO;
printf("xb_scanf format %s in %s\n", fmt, val);
va_end(ap);
free(val, M_DEVBUF);
return ret;
}
/* Single printf and write: returns -errno or 0. */
int
xenbus_printf(struct xenbus_transaction *t,
const char *dir, const char *node, const char *fmt, ...)
{
va_list ap;
int ret;
#define PRINTF_BUFFER_SIZE 4096
char *printf_buffer;
printf_buffer = malloc(PRINTF_BUFFER_SIZE, M_DEVBUF, M_NOWAIT);
if (printf_buffer == NULL)
return ENOMEM;
va_start(ap, fmt);
ret = vsnprintf(printf_buffer, PRINTF_BUFFER_SIZE, fmt, ap);
va_end(ap);
KASSERT(ret < PRINTF_BUFFER_SIZE);
ret = xenbus_write(t, dir, node, printf_buffer);
free(printf_buffer, M_DEVBUF);
return ret;
}
/* Takes tuples of names, scanf-style args, and void **, NULL terminated. */
int
xenbus_gather(struct xenbus_transaction *t, const char *dir, ...)
{
va_list ap;
const char *name;
int ret = 0;
va_start(ap, dir);
while (ret == 0 && (name = va_arg(ap, char *)) != NULL) {
const char *fmt = va_arg(ap, char *);
void *result = va_arg(ap, void *);
char *p;
ret = xenbus_read(t, dir, name, NULL, &p);
if (ret)
break;
if (fmt) {
// XXX if (sscanf(p, fmt, result) == 0)
ret = -EINVAL;
free(p, M_DEVBUF);
} else
*(char **)result = p;
}
va_end(ap);
return ret;
}
static int
xs_watch(const char *path, const char *token)
{
struct iovec iov[2];
/* xs_talkv only reads iovec */
iov[0].iov_base = __UNCONST(path);
iov[0].iov_len = strlen(path) + 1;
iov[1].iov_base = __UNCONST(token);
iov[1].iov_len = strlen(token) + 1;
return xs_talkv(NULL, XS_WATCH, iov, 2, NULL, NULL);
}
static int
xs_unwatch(const char *path, const char *token)
{
struct iovec iov[2];
/* xs_talkv only reads iovec */
iov[0].iov_base = __UNCONST(path);
iov[0].iov_len = strlen(path) + 1;
iov[1].iov_base = __UNCONST(token);
iov[1].iov_len = strlen(token) + 1;
return xs_talkv(NULL, XS_UNWATCH, iov, 2, NULL, NULL);
}
static struct xenbus_watch *
find_watch(const char *token)
{
struct xenbus_watch *i, *cmp;
cmp = (void *)strtoul(token, NULL, 16);
SLIST_FOREACH(i, &watches, watch_next) {
if (i == cmp)
return i;
}
return NULL;
}
/* Register callback to watch this node. */
int
register_xenbus_watch(struct xenbus_watch *watch)
{
/* Pointer in ascii is the token. */
char token[sizeof(watch) * 2 + 1];
int err;
snprintf(token, sizeof(token), "%lX", (long)watch);
mutex_enter(&watches_lock);
KASSERT(find_watch(token) == 0);
SLIST_INSERT_HEAD(&watches, watch, watch_next);
mutex_exit(&watches_lock);
err = xs_watch(watch->node, token);
/* Ignore errors due to multiple registration. */
if ((err != 0) && (err != EEXIST)) {
mutex_enter(&watches_lock);
SLIST_REMOVE(&watches, watch, xenbus_watch, watch_next);
mutex_exit(&watches_lock);
}
return err;
}
void
unregister_xenbus_watch(struct xenbus_watch *watch)
{
SIMPLEQ_HEAD(, xs_stored_msg) gclist;
struct xs_stored_msg *msg, *next_msg;
char token[sizeof(watch) * 2 + 1];
int err;
snprintf(token, sizeof(token), "%lX", (long)watch);
mutex_enter(&watches_lock);
KASSERT(find_watch(token));
SLIST_REMOVE(&watches, watch, xenbus_watch, watch_next);
mutex_exit(&watches_lock);
err = xs_unwatch(watch->node, token);
if (err) {
printf(
"XENBUS Failed to release watch %s: %i\n",
watch->node, err);
}
/* Cancel pending watch events. */
SIMPLEQ_INIT(&gclist);
mutex_enter(&watch_events_lock);
for (msg = SIMPLEQ_FIRST(&watch_events); msg != NULL; msg = next_msg) {
next_msg = SIMPLEQ_NEXT(msg, msg_next);
if (msg->u.watch.handle != watch)
continue;
SIMPLEQ_REMOVE(&watch_events, msg, xs_stored_msg, msg_next);
SIMPLEQ_INSERT_TAIL(&gclist, msg, msg_next);
}
mutex_exit(&watch_events_lock);
while ((msg = SIMPLEQ_FIRST(&gclist)) != NULL) {
SIMPLEQ_REMOVE(&gclist, msg, xs_stored_msg, msg_next);
free(msg->u.watch.vec, M_DEVBUF);
free(msg, M_DEVBUF);
}
}
void
xs_suspend(void)
{
xs_state.suspend_spl = spltty();
}
void
xs_resume(void)
{
struct xenbus_watch *watch;
char token[sizeof(watch) * 2 + 1];
/* No need for watches_lock: the suspend_mutex is sufficient. */
SLIST_FOREACH(watch, &watches, watch_next) {
snprintf(token, sizeof(token), "%lX", (long)watch);
xs_watch(watch->node, token);
}
splx(xs_state.suspend_spl);
}
static void
xenwatch_thread(void *unused)
{
SIMPLEQ_HEAD(, xs_stored_msg) events_to_proces;
struct xs_stored_msg *msg;
SIMPLEQ_INIT(&events_to_proces);
for (;;) {
mutex_enter(&watch_events_lock);
while (SIMPLEQ_EMPTY(&watch_events))
cv_wait(&watch_cv, &watch_events_lock);
SIMPLEQ_CONCAT(&events_to_proces, &watch_events);
mutex_exit(&watch_events_lock);
DPRINTK("xenwatch_thread: processing events");
while ((msg = SIMPLEQ_FIRST(&events_to_proces)) != NULL) {
DPRINTK("xenwatch_thread: got event");
SIMPLEQ_REMOVE_HEAD(&events_to_proces, msg_next);
msg->u.watch.handle->xbw_callback(
msg->u.watch.handle,
(void *)msg->u.watch.vec,
msg->u.watch.vec_size);
free(msg->u.watch.vec, M_DEVBUF);
free(msg, M_DEVBUF);
}
}
}
static int
process_msg(void)
{
struct xs_stored_msg *msg, *s_msg;
char *body;
int err;
msg = malloc(sizeof(*msg), M_DEVBUF, M_NOWAIT);
if (msg == NULL)
return ENOMEM;
err = xb_read(&msg->hdr, sizeof(msg->hdr));
DPRINTK("xb_read hdr %d", err);
if (err) {
free(msg, M_DEVBUF);
return err;
}
body = malloc(msg->hdr.len + 1, M_DEVBUF, M_NOWAIT);
if (body == NULL) {
free(msg, M_DEVBUF);
return ENOMEM;
}
err = xb_read(body, msg->hdr.len);
DPRINTK("xb_read body %d", err);
if (err) {
free(body, M_DEVBUF);
free(msg, M_DEVBUF);
return err;
}
body[msg->hdr.len] = '\0';
if (msg->hdr.type == XS_WATCH_EVENT) {
bool found, repeated;
DPRINTK("process_msg: XS_WATCH_EVENT");
msg->u.watch.vec = split(body, msg->hdr.len,
&msg->u.watch.vec_size);
if (msg->u.watch.vec == NULL) {
free(msg, M_DEVBUF);
return ENOMEM;
}
mutex_enter(&watches_lock);
msg->u.watch.handle = find_watch(
msg->u.watch.vec[XS_WATCH_TOKEN]);
found = (msg->u.watch.handle != NULL);
repeated = false;
if (found) {
mutex_enter(&watch_events_lock);
/* Don't add duplicate events to the queue of pending watches */
SIMPLEQ_FOREACH(s_msg, &watch_events, msg_next) {
if (s_msg->u.watch.handle == msg->u.watch.handle) {
repeated = true;
break;
}
}
if (!repeated) {
SIMPLEQ_INSERT_TAIL(&watch_events, msg, msg_next);
cv_broadcast(&watch_cv);
}
mutex_exit(&watch_events_lock);
}
mutex_exit(&watches_lock);
if (!found || repeated) {
free(msg->u.watch.vec, M_DEVBUF);
free(msg, M_DEVBUF);
}
} else {
DPRINTK("process_msg: type %d body %s", msg->hdr.type, body);
msg->u.reply.body = body;
mutex_enter(&xs_state.reply_lock);
SIMPLEQ_INSERT_TAIL(&xs_state.reply_list, msg, msg_next);
cv_broadcast(&xs_state.reply_cv);
mutex_exit(&xs_state.reply_lock);
}
return 0;
}
static void
xenbus_thread(void *unused)
{
int err;
for (;;) {
err = process_msg();
if (err)
printk("XENBUS error %d while reading message\n", err);
}
}
int
xs_init(device_t dev)
{
int err;
SLIST_INIT(&watches);
mutex_init(&watches_lock, MUTEX_DEFAULT, IPL_TTY);
SIMPLEQ_INIT(&watch_events);
mutex_init(&watch_events_lock, MUTEX_DEFAULT, IPL_TTY);
cv_init(&watch_cv, "evtsq");
SIMPLEQ_INIT(&xs_state.reply_list);
mutex_init(&xs_state.xs_lock, MUTEX_DEFAULT, IPL_NONE);
mutex_init(&xs_state.reply_lock, MUTEX_DEFAULT, IPL_TTY);
cv_init(&xs_state.reply_cv, "rplq");
err = kthread_create(PRI_NONE, 0, NULL, xenwatch_thread,
NULL, NULL, "xenwatch");
if (err) {
aprint_error_dev(dev, "kthread_create(xenwatch): %d\n", err);
return err;
}
err = kthread_create(PRI_NONE, 0, NULL, xenbus_thread,
NULL, NULL, "xenbus");
if (err) {
aprint_error_dev(dev, "kthread_create(xenbus): %d\n", err);
return err;
}
return 0;
}
/*
* Local variables:
* c-file-style: "linux"
* indent-tabs-mode: t
* c-indent-level: 8
* c-basic-offset: 8
* tab-width: 8
* End:
*/