This resolves core findings from ASTERISK-19650 numbers 0-2, 6, 7, 9-11, 14-20, 22-24, 28, 30-32, 34-36, 42-56, 82-84, 87, 89-90, 93-102, 104, 105, 109-111, and 115. Finding numbers 26, 33, and 29 were already resolved. Those skipped were either extended/deprecated or in areas of code that shouldn't be disturbed. (Closes issue ASTERISK-19650) ........ Merged revisions 366167 from http://svn.asterisk.org/svn/asterisk/branches/1.8 ........ Merged revisions 366168 from http://svn.asterisk.org/svn/asterisk/branches/10 git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@366169 65c4cc65-6c06-0410-ace0-fbb531ad65f3
520 lines
14 KiB
C
520 lines
14 KiB
C
/*
|
|
* Asterisk -- An open source telephony toolkit.
|
|
*
|
|
* Copyright (C) 2007, Tilghman Lesher
|
|
*
|
|
* Tilghman Lesher <func_lock_2007@the-tilghman.com>
|
|
*
|
|
* See http://www.asterisk.org for more information about
|
|
* the Asterisk project. Please do not directly contact
|
|
* any of the maintainers of this project for assistance;
|
|
* the project provides a web site, mailing lists and IRC
|
|
* channels for your use.
|
|
*
|
|
* This program is free software, distributed under the terms of
|
|
* the GNU General Public License Version 2. See the LICENSE file
|
|
* at the top of the source tree.
|
|
*/
|
|
|
|
/*! \file
|
|
*
|
|
* \brief Dialplan mutexes
|
|
*
|
|
* \author Tilghman Lesher <func_lock_2007@the-tilghman.com>
|
|
*
|
|
* \ingroup functions
|
|
*
|
|
*/
|
|
|
|
/*** MODULEINFO
|
|
<support_level>core</support_level>
|
|
***/
|
|
|
|
#include "asterisk.h"
|
|
|
|
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
|
|
|
|
#include <signal.h>
|
|
|
|
#include "asterisk/lock.h"
|
|
#include "asterisk/file.h"
|
|
#include "asterisk/channel.h"
|
|
#include "asterisk/pbx.h"
|
|
#include "asterisk/module.h"
|
|
#include "asterisk/linkedlists.h"
|
|
#include "asterisk/astobj2.h"
|
|
#include "asterisk/utils.h"
|
|
|
|
/*** DOCUMENTATION
|
|
<function name="LOCK" language="en_US">
|
|
<synopsis>
|
|
Attempt to obtain a named mutex.
|
|
</synopsis>
|
|
<syntax>
|
|
<parameter name="lockname" required="true" />
|
|
</syntax>
|
|
<description>
|
|
<para>Attempts to grab a named lock exclusively, and prevents other channels from
|
|
obtaining the same lock. LOCK will wait for the lock to become available.
|
|
Returns <literal>1</literal> if the lock was obtained or <literal>0</literal> on error.</para>
|
|
<note><para>To avoid the possibility of a deadlock, LOCK will only attempt to
|
|
obtain the lock for 3 seconds if the channel already has another lock.</para></note>
|
|
</description>
|
|
</function>
|
|
<function name="TRYLOCK" language="en_US">
|
|
<synopsis>
|
|
Attempt to obtain a named mutex.
|
|
</synopsis>
|
|
<syntax>
|
|
<parameter name="lockname" required="true" />
|
|
</syntax>
|
|
<description>
|
|
<para>Attempts to grab a named lock exclusively, and prevents other channels
|
|
from obtaining the same lock. Returns <literal>1</literal> if the lock was
|
|
available or <literal>0</literal> otherwise.</para>
|
|
</description>
|
|
</function>
|
|
<function name="UNLOCK" language="en_US">
|
|
<synopsis>
|
|
Unlocks a named mutex.
|
|
</synopsis>
|
|
<syntax>
|
|
<parameter name="lockname" required="true" />
|
|
</syntax>
|
|
<description>
|
|
<para>Unlocks a previously locked mutex. Returns <literal>1</literal> if the channel
|
|
had a lock or <literal>0</literal> otherwise.</para>
|
|
<note><para>It is generally unnecessary to unlock in a hangup routine, as any locks
|
|
held are automatically freed when the channel is destroyed.</para></note>
|
|
</description>
|
|
</function>
|
|
***/
|
|
|
|
|
|
|
|
static AST_LIST_HEAD_STATIC(locklist, lock_frame);
|
|
|
|
static void lock_free(void *data);
|
|
static void lock_fixup(void *data, struct ast_channel *oldchan, struct ast_channel *newchan);
|
|
static int unloading = 0;
|
|
static pthread_t broker_tid = AST_PTHREADT_NULL;
|
|
|
|
static struct ast_datastore_info lock_info = {
|
|
.type = "MUTEX",
|
|
.destroy = lock_free,
|
|
.chan_fixup = lock_fixup,
|
|
};
|
|
|
|
struct lock_frame {
|
|
AST_LIST_ENTRY(lock_frame) entries;
|
|
ast_mutex_t mutex;
|
|
ast_cond_t cond;
|
|
/*! count is needed so if a recursive mutex exits early, we know how many times to unlock it. */
|
|
unsigned int count;
|
|
/*! Container of requesters for the named lock */
|
|
struct ao2_container *requesters;
|
|
/*! who owns us */
|
|
struct ast_channel *owner;
|
|
/*! name of the lock */
|
|
char name[0];
|
|
};
|
|
|
|
struct channel_lock_frame {
|
|
AST_LIST_ENTRY(channel_lock_frame) list;
|
|
/*! Need to save channel pointer here, because during destruction, we won't have it. */
|
|
struct ast_channel *channel;
|
|
struct lock_frame *lock_frame;
|
|
};
|
|
|
|
static void lock_free(void *data)
|
|
{
|
|
AST_LIST_HEAD(, channel_lock_frame) *oldlist = data;
|
|
struct channel_lock_frame *clframe;
|
|
AST_LIST_LOCK(oldlist);
|
|
while ((clframe = AST_LIST_REMOVE_HEAD(oldlist, list))) {
|
|
/* Only unlock if we own the lock */
|
|
if (clframe->channel == clframe->lock_frame->owner) {
|
|
clframe->lock_frame->count = 0;
|
|
clframe->lock_frame->owner = NULL;
|
|
}
|
|
ast_free(clframe);
|
|
}
|
|
AST_LIST_UNLOCK(oldlist);
|
|
AST_LIST_HEAD_DESTROY(oldlist);
|
|
ast_free(oldlist);
|
|
}
|
|
|
|
static void lock_fixup(void *data, struct ast_channel *oldchan, struct ast_channel *newchan)
|
|
{
|
|
struct ast_datastore *lock_store = ast_channel_datastore_find(oldchan, &lock_info, NULL);
|
|
AST_LIST_HEAD(, channel_lock_frame) *list;
|
|
struct channel_lock_frame *clframe = NULL;
|
|
|
|
if (!lock_store) {
|
|
return;
|
|
}
|
|
list = lock_store->data;
|
|
|
|
AST_LIST_LOCK(list);
|
|
AST_LIST_TRAVERSE(list, clframe, list) {
|
|
if (clframe->lock_frame->owner == oldchan) {
|
|
clframe->lock_frame->owner = newchan;
|
|
}
|
|
/* We don't move requesters, because the thread stack is different */
|
|
clframe->channel = newchan;
|
|
}
|
|
AST_LIST_UNLOCK(list);
|
|
}
|
|
|
|
static void *lock_broker(void *unused)
|
|
{
|
|
struct lock_frame *frame;
|
|
struct timespec forever = { 1000000, 0 };
|
|
for (;;) {
|
|
int found_requester = 0;
|
|
|
|
/* Test for cancel outside of the lock */
|
|
pthread_testcancel();
|
|
AST_LIST_LOCK(&locklist);
|
|
|
|
AST_LIST_TRAVERSE(&locklist, frame, entries) {
|
|
if (ao2_container_count(frame->requesters)) {
|
|
found_requester++;
|
|
ast_mutex_lock(&frame->mutex);
|
|
if (!frame->owner) {
|
|
ast_cond_signal(&frame->cond);
|
|
}
|
|
ast_mutex_unlock(&frame->mutex);
|
|
}
|
|
}
|
|
|
|
AST_LIST_UNLOCK(&locklist);
|
|
pthread_testcancel();
|
|
|
|
/* If there are no requesters, then wait for a signal */
|
|
if (!found_requester) {
|
|
nanosleep(&forever, NULL);
|
|
} else {
|
|
sched_yield();
|
|
}
|
|
}
|
|
/* Not reached */
|
|
return NULL;
|
|
}
|
|
|
|
static int ast_channel_hash_cb(const void *obj, const int flags)
|
|
{
|
|
const struct ast_channel *chan = obj;
|
|
return ast_str_case_hash(ast_channel_name(chan));
|
|
}
|
|
|
|
static int ast_channel_cmp_cb(void *obj, void *arg, int flags)
|
|
{
|
|
struct ast_channel *chan = obj, *cmp_args = arg;
|
|
return strcasecmp(ast_channel_name(chan), ast_channel_name(cmp_args)) ? 0 : CMP_MATCH;
|
|
}
|
|
|
|
static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
|
|
{
|
|
struct ast_datastore *lock_store = ast_channel_datastore_find(chan, &lock_info, NULL);
|
|
struct lock_frame *current;
|
|
struct channel_lock_frame *clframe = NULL;
|
|
AST_LIST_HEAD(, channel_lock_frame) *list;
|
|
int res = 0;
|
|
struct timespec timeout = { 0, };
|
|
struct timeval now;
|
|
|
|
if (!lock_store) {
|
|
ast_debug(1, "Channel %s has no lock datastore, so we're allocating one.\n", ast_channel_name(chan));
|
|
lock_store = ast_datastore_alloc(&lock_info, NULL);
|
|
if (!lock_store) {
|
|
ast_log(LOG_ERROR, "Unable to allocate new datastore. No locks will be obtained.\n");
|
|
return -1;
|
|
}
|
|
|
|
list = ast_calloc(1, sizeof(*list));
|
|
if (!list) {
|
|
ast_log(LOG_ERROR,
|
|
"Unable to allocate datastore list head. %sLOCK will fail.\n",
|
|
trylock ? "TRY" : "");
|
|
ast_datastore_free(lock_store);
|
|
return -1;
|
|
}
|
|
|
|
lock_store->data = list;
|
|
AST_LIST_HEAD_INIT(list);
|
|
ast_channel_datastore_add(chan, lock_store);
|
|
} else
|
|
list = lock_store->data;
|
|
|
|
/* Lock already exists? */
|
|
AST_LIST_LOCK(&locklist);
|
|
AST_LIST_TRAVERSE(&locklist, current, entries) {
|
|
if (strcmp(current->name, lockname) == 0) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!current) {
|
|
if (unloading) {
|
|
/* Don't bother */
|
|
AST_LIST_UNLOCK(&locklist);
|
|
return -1;
|
|
}
|
|
|
|
/* Create new lock entry */
|
|
current = ast_calloc(1, sizeof(*current) + strlen(lockname) + 1);
|
|
if (!current) {
|
|
AST_LIST_UNLOCK(&locklist);
|
|
return -1;
|
|
}
|
|
|
|
strcpy(current->name, lockname); /* SAFE */
|
|
if ((res = ast_mutex_init(¤t->mutex))) {
|
|
ast_log(LOG_ERROR, "Unable to initialize mutex: %s\n", strerror(res));
|
|
ast_free(current);
|
|
AST_LIST_UNLOCK(&locklist);
|
|
return -1;
|
|
}
|
|
if ((res = ast_cond_init(¤t->cond, NULL))) {
|
|
ast_log(LOG_ERROR, "Unable to initialize condition variable: %s\n", strerror(res));
|
|
ast_mutex_destroy(¤t->mutex);
|
|
ast_free(current);
|
|
AST_LIST_UNLOCK(&locklist);
|
|
return -1;
|
|
}
|
|
if (!(current->requesters = ao2_container_alloc(1, ast_channel_hash_cb, ast_channel_cmp_cb))) {
|
|
ast_mutex_destroy(¤t->mutex);
|
|
ast_cond_destroy(¤t->cond);
|
|
ast_free(current);
|
|
AST_LIST_UNLOCK(&locklist);
|
|
return -1;
|
|
}
|
|
AST_LIST_INSERT_TAIL(&locklist, current, entries);
|
|
}
|
|
AST_LIST_UNLOCK(&locklist);
|
|
|
|
/* Found lock or created one - now find or create the corresponding link in the channel */
|
|
AST_LIST_LOCK(list);
|
|
AST_LIST_TRAVERSE(list, clframe, list) {
|
|
if (clframe->lock_frame == current) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!clframe) {
|
|
if (unloading) {
|
|
/* Don't bother */
|
|
AST_LIST_UNLOCK(list);
|
|
return -1;
|
|
}
|
|
|
|
if (!(clframe = ast_calloc(1, sizeof(*clframe)))) {
|
|
ast_log(LOG_ERROR,
|
|
"Unable to allocate channel lock frame. %sLOCK will fail.\n",
|
|
trylock ? "TRY" : "");
|
|
AST_LIST_UNLOCK(list);
|
|
return -1;
|
|
}
|
|
|
|
clframe->lock_frame = current;
|
|
clframe->channel = chan;
|
|
AST_LIST_INSERT_TAIL(list, clframe, list);
|
|
}
|
|
AST_LIST_UNLOCK(list);
|
|
|
|
/* If we already own the lock, then we're being called recursively.
|
|
* Keep track of how many times that is, because we need to unlock
|
|
* the same amount, before we'll release this one.
|
|
*/
|
|
if (current->owner == chan) {
|
|
current->count++;
|
|
return 0;
|
|
}
|
|
|
|
/* Okay, we have both frames, so now we need to try to lock.
|
|
*
|
|
* Locking order: always lock locklist first. We need the
|
|
* locklist lock because the broker thread counts whether
|
|
* there are requesters with the locklist lock held, and we
|
|
* need to hold it, so that when we send our signal, below,
|
|
* to wake up the broker thread, it definitely will see that
|
|
* a requester exists at that point in time. Otherwise, we
|
|
* could add to the requesters after it has already seen that
|
|
* that lock is unoccupied and wait forever for another signal.
|
|
*/
|
|
AST_LIST_LOCK(&locklist);
|
|
ast_mutex_lock(¤t->mutex);
|
|
/* Add to requester list */
|
|
ao2_link(current->requesters, chan);
|
|
pthread_kill(broker_tid, SIGURG);
|
|
AST_LIST_UNLOCK(&locklist);
|
|
|
|
/* Wait up to three seconds from now for LOCK. */
|
|
now = ast_tvnow();
|
|
timeout.tv_sec = now.tv_sec + 3;
|
|
timeout.tv_nsec = now.tv_usec * 1000;
|
|
|
|
if (!current->owner
|
|
|| (!trylock
|
|
&& !(res = ast_cond_timedwait(¤t->cond, ¤t->mutex, &timeout)))) {
|
|
res = 0;
|
|
current->owner = chan;
|
|
current->count++;
|
|
} else {
|
|
res = -1;
|
|
}
|
|
/* Remove from requester list */
|
|
ao2_unlink(current->requesters, chan);
|
|
ast_mutex_unlock(¤t->mutex);
|
|
|
|
return res;
|
|
}
|
|
|
|
static int unlock_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
|
|
{
|
|
struct ast_datastore *lock_store;
|
|
struct channel_lock_frame *clframe;
|
|
AST_LIST_HEAD(, channel_lock_frame) *list;
|
|
|
|
if (!chan) {
|
|
return -1;
|
|
}
|
|
|
|
lock_store = ast_channel_datastore_find(chan, &lock_info, NULL);
|
|
if (!lock_store) {
|
|
ast_log(LOG_WARNING, "No datastore for dialplan locks. Nothing was ever locked!\n");
|
|
ast_copy_string(buf, "0", len);
|
|
return 0;
|
|
}
|
|
|
|
if (!(list = lock_store->data)) {
|
|
ast_debug(1, "This should NEVER happen\n");
|
|
ast_copy_string(buf, "0", len);
|
|
return 0;
|
|
}
|
|
|
|
/* Find item in the channel list */
|
|
AST_LIST_LOCK(list);
|
|
AST_LIST_TRAVERSE(list, clframe, list) {
|
|
if (clframe->lock_frame && clframe->lock_frame->owner == chan && strcmp(clframe->lock_frame->name, data) == 0) {
|
|
break;
|
|
}
|
|
}
|
|
/* We never destroy anything until channel destruction, which will never
|
|
* happen while this routine is executing, so we don't need to hold the
|
|
* lock beyond this point. */
|
|
AST_LIST_UNLOCK(list);
|
|
|
|
if (!clframe) {
|
|
/* We didn't have this lock in the first place */
|
|
ast_copy_string(buf, "0", len);
|
|
return 0;
|
|
}
|
|
|
|
if (--clframe->lock_frame->count == 0) {
|
|
clframe->lock_frame->owner = NULL;
|
|
}
|
|
|
|
ast_copy_string(buf, "1", len);
|
|
return 0;
|
|
}
|
|
|
|
static int lock_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
|
|
{
|
|
if (!chan) {
|
|
return -1;
|
|
}
|
|
ast_autoservice_start(chan);
|
|
ast_copy_string(buf, get_lock(chan, data, 0) ? "0" : "1", len);
|
|
ast_autoservice_stop(chan);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int trylock_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
|
|
{
|
|
if (!chan) {
|
|
return -1;
|
|
}
|
|
ast_autoservice_start(chan);
|
|
ast_copy_string(buf, get_lock(chan, data, 1) ? "0" : "1", len);
|
|
ast_autoservice_stop(chan);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct ast_custom_function lock_function = {
|
|
.name = "LOCK",
|
|
.read = lock_read,
|
|
.read_max = 2,
|
|
};
|
|
|
|
static struct ast_custom_function trylock_function = {
|
|
.name = "TRYLOCK",
|
|
.read = trylock_read,
|
|
.read_max = 2,
|
|
};
|
|
|
|
static struct ast_custom_function unlock_function = {
|
|
.name = "UNLOCK",
|
|
.read = unlock_read,
|
|
.read_max = 2,
|
|
};
|
|
|
|
static int unload_module(void)
|
|
{
|
|
struct lock_frame *current;
|
|
|
|
/* Module flag */
|
|
unloading = 1;
|
|
|
|
AST_LIST_LOCK(&locklist);
|
|
while ((current = AST_LIST_REMOVE_HEAD(&locklist, entries))) {
|
|
/* If any locks are currently in use, then we cannot unload this module */
|
|
if (current->owner || ao2_container_count(current->requesters)) {
|
|
/* Put it back */
|
|
AST_LIST_INSERT_HEAD(&locklist, current, entries);
|
|
AST_LIST_UNLOCK(&locklist);
|
|
unloading = 0;
|
|
return -1;
|
|
}
|
|
ast_mutex_destroy(¤t->mutex);
|
|
ao2_ref(current->requesters, -1);
|
|
ast_free(current);
|
|
}
|
|
|
|
/* No locks left, unregister functions */
|
|
ast_custom_function_unregister(&lock_function);
|
|
ast_custom_function_unregister(&trylock_function);
|
|
ast_custom_function_unregister(&unlock_function);
|
|
|
|
if (broker_tid != AST_PTHREADT_NULL) {
|
|
pthread_cancel(broker_tid);
|
|
pthread_kill(broker_tid, SIGURG);
|
|
pthread_join(broker_tid, NULL);
|
|
}
|
|
|
|
AST_LIST_UNLOCK(&locklist);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int load_module(void)
|
|
{
|
|
int res = ast_custom_function_register(&lock_function);
|
|
res |= ast_custom_function_register(&trylock_function);
|
|
res |= ast_custom_function_register(&unlock_function);
|
|
|
|
if (ast_pthread_create_background(&broker_tid, NULL, lock_broker, NULL)) {
|
|
ast_log(LOG_ERROR, "Failed to start lock broker thread. Unloading func_lock module.\n");
|
|
broker_tid = AST_PTHREADT_NULL;
|
|
unload_module();
|
|
return AST_MODULE_LOAD_DECLINE;
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan mutexes");
|