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422 lines
13 KiB
422 lines
13 KiB
From b35211fd58afcf430a0d95a243dc7a086d72b2b8 Mon Sep 17 00:00:00 2001
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From: Jaco Kroon <jaco@uls.co.za>
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Date: Fri, 21 May 2021 20:11:59 +0200
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Subject: [PATCH] Replacement patch for v13.
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Change-Id: I30236d7d7229f317c681fb7c6d7944d6108acd08
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---
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funcs/func_lock.c | 234 +++++++++++++++++++++++++---------------------
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1 file changed, 126 insertions(+), 108 deletions(-)
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diff --git a/funcs/func_lock.c b/funcs/func_lock.c
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index a006a574eb..c472504f52 100644
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--- a/funcs/func_lock.c
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+++ b/funcs/func_lock.c
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@@ -44,6 +44,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include "asterisk/linkedlists.h"
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#include "asterisk/astobj2.h"
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#include "asterisk/utils.h"
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+#include "asterisk/cli.h"
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/*** DOCUMENTATION
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<function name="LOCK" language="en_US">
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@@ -112,7 +113,6 @@ static AST_LIST_HEAD_STATIC(locklist, lock_frame);
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static void lock_free(void *data);
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static void lock_fixup(void *data, struct ast_channel *oldchan, struct ast_channel *newchan);
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static int unloading = 0;
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-static pthread_t broker_tid = AST_PTHREADT_NULL;
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static const struct ast_datastore_info lock_info = {
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.type = "MUTEX",
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@@ -126,8 +126,8 @@ struct lock_frame {
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ast_cond_t cond;
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/*! count is needed so if a recursive mutex exits early, we know how many times to unlock it. */
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unsigned int count;
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- /*! Container of requesters for the named lock */
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- struct ao2_container *requesters;
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+ /*! Count of waiting of requesters for the named lock */
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+ unsigned int requesters;
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/*! who owns us */
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struct ast_channel *owner;
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/*! name of the lock */
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@@ -149,14 +149,19 @@ static void lock_free(void *data)
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while ((clframe = AST_LIST_REMOVE_HEAD(oldlist, list))) {
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/* Only unlock if we own the lock */
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if (clframe->channel == clframe->lock_frame->owner) {
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+ ast_mutex_lock(&clframe->lock_frame->mutex);
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clframe->lock_frame->count = 0;
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clframe->lock_frame->owner = NULL;
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+ ast_cond_signal(&clframe->lock_frame->cond);
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+ ast_mutex_unlock(&clframe->lock_frame->mutex);
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}
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ast_free(clframe);
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}
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AST_LIST_UNLOCK(oldlist);
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AST_LIST_HEAD_DESTROY(oldlist);
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ast_free(oldlist);
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+
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+ ast_module_unref(ast_module_info->self);
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}
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static void lock_fixup(void *data, struct ast_channel *oldchan, struct ast_channel *newchan)
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@@ -175,54 +180,11 @@ static void lock_fixup(void *data, struct ast_channel *oldchan, struct ast_chann
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if (clframe->lock_frame->owner == oldchan) {
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clframe->lock_frame->owner = newchan;
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}
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- /* We don't move requesters, because the thread stack is different */
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clframe->channel = newchan;
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}
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AST_LIST_UNLOCK(list);
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}
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-static void *lock_broker(void *unused)
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-{
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- struct lock_frame *frame;
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- struct timespec forever = { 1000000, 0 };
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- for (;;) {
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- int found_requester = 0;
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-
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- /* Test for cancel outside of the lock */
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- pthread_testcancel();
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- AST_LIST_LOCK(&locklist);
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-
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- AST_LIST_TRAVERSE(&locklist, frame, entries) {
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- if (ao2_container_count(frame->requesters)) {
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- found_requester++;
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- ast_mutex_lock(&frame->mutex);
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- if (!frame->owner) {
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- ast_cond_signal(&frame->cond);
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- }
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- ast_mutex_unlock(&frame->mutex);
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- }
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- }
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-
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- AST_LIST_UNLOCK(&locklist);
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- pthread_testcancel();
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-
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- /* If there are no requesters, then wait for a signal */
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- if (!found_requester) {
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- nanosleep(&forever, NULL);
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- } else {
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- sched_yield();
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- }
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- }
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- /* Not reached */
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- return NULL;
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-}
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-
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-static int ast_channel_cmp_cb(void *obj, void *arg, int flags)
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-{
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- struct ast_channel *chan = obj, *cmp_args = arg;
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- return strcasecmp(ast_channel_name(chan), ast_channel_name(cmp_args)) ? 0 : CMP_MATCH;
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-}
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-
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static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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{
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struct ast_datastore *lock_store = ast_channel_datastore_find(chan, &lock_info, NULL);
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@@ -234,7 +196,12 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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struct timeval now;
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if (!lock_store) {
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- ast_debug(1, "Channel %s has no lock datastore, so we're allocating one.\n", ast_channel_name(chan));
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+ if (unloading) {
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+ ast_log(LOG_ERROR, "%sLOCK has no datastore and func_lock is unloading, failing.\n",
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+ trylock ? "TRY" : "");
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+ return -1;
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+ }
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+
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lock_store = ast_datastore_alloc(&lock_info, NULL);
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if (!lock_store) {
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ast_log(LOG_ERROR, "Unable to allocate new datastore. No locks will be obtained.\n");
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@@ -253,6 +220,9 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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lock_store->data = list;
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AST_LIST_HEAD_INIT(list);
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ast_channel_datastore_add(chan, lock_store);
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+
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+ /* We cannot unload until this channel has released the lock_store */
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+ ast_module_ref(ast_module_info->self);
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} else
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list = lock_store->data;
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@@ -266,6 +236,9 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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if (!current) {
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if (unloading) {
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+ ast_log(LOG_ERROR,
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+ "Lock doesn't exist whilst unloading. %sLOCK will fail.\n",
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+ trylock ? "TRY" : "");
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/* Don't bother */
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AST_LIST_UNLOCK(&locklist);
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return -1;
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@@ -292,17 +265,12 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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AST_LIST_UNLOCK(&locklist);
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return -1;
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}
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- current->requesters = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
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- NULL, ast_channel_cmp_cb);
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- if (!current->requesters) {
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- ast_mutex_destroy(¤t->mutex);
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- ast_cond_destroy(¤t->cond);
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- ast_free(current);
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- AST_LIST_UNLOCK(&locklist);
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- return -1;
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- }
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AST_LIST_INSERT_TAIL(&locklist, current, entries);
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}
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+ /* Add to requester list */
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+ ast_mutex_lock(¤t->mutex);
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+ current->requesters++;
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+ ast_mutex_unlock(¤t->mutex);
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AST_LIST_UNLOCK(&locklist);
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/* Found lock or created one - now find or create the corresponding link in the channel */
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@@ -315,7 +283,13 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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if (!clframe) {
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if (unloading) {
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+ ast_log(LOG_ERROR,
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+ "Busy unloading. %sLOCK will fail.\n",
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+ trylock ? "TRY" : "");
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/* Don't bother */
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+ ast_mutex_lock(¤t->mutex);
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+ current->requesters--;
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+ ast_mutex_unlock(¤t->mutex);
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AST_LIST_UNLOCK(list);
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return -1;
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}
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@@ -324,6 +298,9 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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ast_log(LOG_ERROR,
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"Unable to allocate channel lock frame. %sLOCK will fail.\n",
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trylock ? "TRY" : "");
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+ ast_mutex_lock(¤t->mutex);
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+ current->requesters--;
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+ ast_mutex_unlock(¤t->mutex);
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AST_LIST_UNLOCK(list);
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return -1;
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}
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@@ -339,44 +316,44 @@ static int get_lock(struct ast_channel *chan, char *lockname, int trylock)
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* the same amount, before we'll release this one.
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*/
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if (current->owner == chan) {
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+ /* We're not a requester, we already have it */
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+ ast_mutex_lock(¤t->mutex);
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+ current->requesters--;
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+ ast_mutex_unlock(¤t->mutex);
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current->count++;
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return 0;
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}
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- /* Okay, we have both frames, so now we need to try to lock.
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- *
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- * Locking order: always lock locklist first. We need the
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- * locklist lock because the broker thread counts whether
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- * there are requesters with the locklist lock held, and we
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- * need to hold it, so that when we send our signal, below,
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- * to wake up the broker thread, it definitely will see that
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- * a requester exists at that point in time. Otherwise, we
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- * could add to the requesters after it has already seen that
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- * that lock is unoccupied and wait forever for another signal.
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- */
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- AST_LIST_LOCK(&locklist);
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- ast_mutex_lock(¤t->mutex);
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- /* Add to requester list */
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- ao2_link(current->requesters, chan);
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- pthread_kill(broker_tid, SIGURG);
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- AST_LIST_UNLOCK(&locklist);
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-
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/* Wait up to three seconds from now for LOCK. */
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now = ast_tvnow();
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timeout.tv_sec = now.tv_sec + 3;
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timeout.tv_nsec = now.tv_usec * 1000;
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- if (!current->owner
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- || (!trylock
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- && !(res = ast_cond_timedwait(¤t->cond, ¤t->mutex, &timeout)))) {
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- res = 0;
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+ ast_mutex_lock(¤t->mutex);
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+
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+ res = 0;
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+ while (!trylock && !res && current->owner) {
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+ res = ast_cond_timedwait(¤t->cond, ¤t->mutex, &timeout);
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+ }
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+ if (current->owner) {
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+ ast_log(LOG_ERROR, "%sLOCK failed to obtain lock %s.\n", trylock ? "TRY" : "",
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+ lockname);
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+ /* timeout;
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+ * trylock; or
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+ * cond_timedwait failed.
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+ *
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+ * either way, we fail to obtain the lock.
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+ */
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+ res = -1;
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+ } else {
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current->owner = chan;
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current->count++;
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- } else {
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- res = -1;
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+ res = 0;
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}
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/* Remove from requester list */
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- ao2_unlink(current->requesters, chan);
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+ current->requesters--;
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+ if (res && unloading)
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+ ast_cond_signal(¤t->cond);
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ast_mutex_unlock(¤t->mutex);
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return res;
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@@ -400,7 +377,7 @@ static int unlock_read(struct ast_channel *chan, const char *cmd, char *data, ch
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}
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if (!(list = lock_store->data)) {
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- ast_debug(1, "This should NEVER happen\n");
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+ ast_log(LOG_ERROR, "Datastore's data member is NULL ... this should be impossible.");
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ast_copy_string(buf, "0", len);
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return 0;
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}
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@@ -419,12 +396,17 @@ static int unlock_read(struct ast_channel *chan, const char *cmd, char *data, ch
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if (!clframe) {
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/* We didn't have this lock in the first place */
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+ ast_log(LOG_WARNING, "Attempting to UNLOCK(%s) - a lock this channel never owned.\n",
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+ data);
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ast_copy_string(buf, "0", len);
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return 0;
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}
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if (--clframe->lock_frame->count == 0) {
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+ ast_mutex_lock(&clframe->lock_frame->mutex);
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clframe->lock_frame->owner = NULL;
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+ ast_cond_signal(&clframe->lock_frame->cond);
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+ ast_mutex_unlock(&clframe->lock_frame->mutex);
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}
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ast_copy_string(buf, "1", len);
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@@ -455,6 +437,37 @@ static int trylock_read(struct ast_channel *chan, const char *cmd, char *data, c
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return 0;
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}
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+static char *handle_cli_locks_show(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
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+{
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+ int c = 0;
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+ struct lock_frame* current;
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+ switch (cmd) {
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+ case CLI_INIT:
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+ e->command = "locks show";
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+ e->usage =
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+ "Usage: locks show\n"
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+ " List all locks known to func_lock, along with their current status.\n";
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+ return NULL;
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+ case CLI_GENERATE:
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+ return NULL;
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+ }
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+
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+ ast_cli(a->fd, "func_lock locks:\n");
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+ ast_cli(a->fd, "%-40s Requesters Owner\n", "Name");
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+ AST_LIST_LOCK(&locklist);
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+ AST_LIST_TRAVERSE(&locklist, current, entries) {
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+ ast_mutex_lock(¤t->mutex);
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+ ast_cli(a->fd, "%-40s %-10d %s\n", current->name, current->requesters,
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+ current->owner ? ast_channel_name(current->owner) : "(unlocked)");
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+ ast_mutex_unlock(¤t->mutex);
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+ c++;
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+ }
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+ AST_LIST_UNLOCK(&locklist);
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+ ast_cli(a->fd, "%d total locks listed.\n", c);
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+
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+ return 0;
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+}
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+
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static struct ast_custom_function lock_function = {
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.name = "LOCK",
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.read = lock_read,
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@@ -473,6 +486,8 @@ static struct ast_custom_function unlock_function = {
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.read_max = 2,
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};
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+static struct ast_cli_entry cli_locks_show = AST_CLI_DEFINE(handle_cli_locks_show, "List func_lock locks.");
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+
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static int unload_module(void)
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{
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struct lock_frame *current;
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@@ -480,34 +495,43 @@ static int unload_module(void)
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/* Module flag */
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unloading = 1;
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+ /* Make it impossible for new requesters to be added
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+ * NOTE: channels could already be in get_lock() */
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+ ast_custom_function_unregister(&lock_function);
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+ ast_custom_function_unregister(&trylock_function);
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+
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+ ast_cli_unregister(&cli_locks_show);
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+
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AST_LIST_LOCK(&locklist);
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while ((current = AST_LIST_REMOVE_HEAD(&locklist, entries))) {
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- /* If any locks are currently in use, then we cannot unload this module */
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- if (current->owner || ao2_container_count(current->requesters)) {
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- /* Put it back */
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- AST_LIST_INSERT_HEAD(&locklist, current, entries);
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- AST_LIST_UNLOCK(&locklist);
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- unloading = 0;
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- return -1;
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+ int warned = 0;
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+ ast_mutex_lock(¤t->mutex);
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+ while (current->owner || current->requesters) {
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+ if (!warned) {
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+ ast_log(LOG_WARNING, "Waiting for %d requesters for %s lock %s.\n",
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+ current->requesters, current->owner ? "locked" : "unlocked",
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+ current->name);
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+ warned = 1;
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+ }
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+ /* either the mutex is locked, or other parties are currently in get_lock,
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+ * we need to wait for all of those to clear first */
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+ ast_cond_wait(¤t->cond, ¤t->mutex);
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}
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+ ast_mutex_unlock(¤t->mutex);
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+ /* At this point we know:
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+ * 1. the lock has been released,
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+ * 2. there are no requesters (nor should any be able to sneak in).
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+ */
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ast_mutex_destroy(¤t->mutex);
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- ao2_ref(current->requesters, -1);
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+ ast_cond_destroy(¤t->cond);
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ast_free(current);
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}
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+ AST_LIST_UNLOCK(&locklist);
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+ AST_LIST_HEAD_DESTROY(&locklist);
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- /* No locks left, unregister functions */
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- ast_custom_function_unregister(&lock_function);
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- ast_custom_function_unregister(&trylock_function);
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+ /* At this point we can safely stop access to UNLOCK */
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ast_custom_function_unregister(&unlock_function);
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- if (broker_tid != AST_PTHREADT_NULL) {
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- pthread_cancel(broker_tid);
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- pthread_kill(broker_tid, SIGURG);
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- pthread_join(broker_tid, NULL);
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- }
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-
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- AST_LIST_UNLOCK(&locklist);
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-
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return 0;
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}
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@@ -516,13 +540,7 @@ static int load_module(void)
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int res = ast_custom_function_register_escalating(&lock_function, AST_CFE_READ);
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res |= ast_custom_function_register_escalating(&trylock_function, AST_CFE_READ);
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res |= ast_custom_function_register_escalating(&unlock_function, AST_CFE_READ);
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-
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- if (ast_pthread_create_background(&broker_tid, NULL, lock_broker, NULL)) {
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- ast_log(LOG_ERROR, "Failed to start lock broker thread. Unloading func_lock module.\n");
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- broker_tid = AST_PTHREADT_NULL;
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- unload_module();
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- return AST_MODULE_LOAD_DECLINE;
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- }
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+ res |= ast_cli_register(&cli_locks_show);
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return res;
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}
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--
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2.26.3
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