Make ast_channel_walk become ast_channel_walk_locked

git-svn-id: http://svn.digium.com/svn/asterisk/trunk@3029 f38db490-d61c-443f-a65b-d21fe96a405b

13 files changed, 152 insertions, 94 deletions

diff --git a/apps/app_agi.c b/apps/app_agi.c
index ba479b28e..d7af708b4 100755
--- a/apps/app_agi.c
+++ b/apps/app_agi.c
@@ -692,15 +692,17 @@ static int handle_hangup(struct ast_channel *chan, AGI *agi, int argc, char **ar
 	    return RESULT_SUCCESS;
         } else if (argc==2) {
             /* one argument: look for info on the specified channel */
-            c = ast_channel_walk(NULL);
+            c = ast_channel_walk_locked(NULL);
             while (c) {
                 if (strcasecmp(argv[1],c->name)==0) {
                     /* we have a matching channel */
-	            ast_softhangup(c,AST_SOFTHANGUP_EXPLICIT);
-	            fdprintf(agi->fd, "200 result=1\n");
+		            ast_softhangup(c,AST_SOFTHANGUP_EXPLICIT);
+		            fdprintf(agi->fd, "200 result=1\n");
+					ast_mutex_unlock(&c->lock);
                     return RESULT_SUCCESS;
                 }
-                c = ast_channel_walk(c);
+				ast_mutex_unlock(&c->lock);
+                c = ast_channel_walk_locked(c);
             }
             /* if we get this far no channel name matched the argument given */
             fdprintf(agi->fd, "200 result=-1\n");
@@ -753,13 +755,15 @@ static int handle_channelstatus(struct ast_channel *chan, AGI *agi, int argc, ch
 	    return RESULT_SUCCESS;
         } else if (argc==3) {
             /* one argument: look for info on the specified channel */
-            c = ast_channel_walk(NULL);
+            c = ast_channel_walk_locked(NULL);
             while (c) {
                 if (strcasecmp(argv[2],c->name)==0) {
                     fdprintf(agi->fd, "200 result=%d\n", c->_state);
+					ast_mutex_unlock(&c->lock);
                     return RESULT_SUCCESS;
                 }
-                c = ast_channel_walk(c);
+				ast_mutex_unlock(&c->lock);
+                c = ast_channel_walk_locked(c);
             }
             /* if we get this far no channel name matched the argument given */
             fdprintf(agi->fd, "200 result=-1\n");
diff --git a/apps/app_groupcount.c b/apps/app_groupcount.c
index ef7b92cd9..b97a77466 100755
--- a/apps/app_groupcount.c
+++ b/apps/app_groupcount.c
@@ -58,20 +58,17 @@ LOCAL_USER_DECL;
 
 static int group_get_count(char *group)
 {
-	/* XXX ast_channel_walk needs to be modified to
-	       prevent a race in which after we return the channel
-		   is no longer valid (or ast_channel_free can be modified
-		   just as well) XXX */
 	struct ast_channel *chan;
 	int count = 0;
 	char *test;
 	if (group && !ast_strlen_zero(group)) {
-		chan = ast_channel_walk(NULL);
+		chan = ast_channel_walk_locked(NULL);
 		while(chan) {
 			test = pbx_builtin_getvar_helper(chan, "GROUP");
 			if (test && !strcasecmp(test, group))
 				count++;
-			chan = ast_channel_walk(chan);
+			ast_mutex_unlock(&chan->lock);
+			chan = ast_channel_walk_locked(chan);
 		}
 	}
 	return count;
diff --git a/apps/app_setcdruserfield.c b/apps/app_setcdruserfield.c
index bb1bb339e..d0ebd2e13 100755
--- a/apps/app_setcdruserfield.c
+++ b/apps/app_setcdruserfield.c
@@ -76,11 +76,12 @@ static int action_setcdruserfield(struct mansession *s, struct message *m)
 		astman_send_error(s, m, "No UserField specified");
 		return 0;
 	}
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while (c) {
 		if (!strcasecmp(c->name, channel))
 			break;
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) {
 		astman_send_error(s, m, "No such channel");
@@ -90,6 +91,7 @@ static int action_setcdruserfield(struct mansession *s, struct message *m)
 		ast_cdr_appenduserfield(c, userfield);
 	else
 		ast_cdr_setuserfield(c, userfield);
+	ast_mutex_unlock(&c->lock);
 	astman_send_ack(s, m, "CDR Userfield Set");
 	return 0;
 }
diff --git a/apps/app_softhangup.c b/apps/app_softhangup.c
index 497f03860..43a42247c 100755
--- a/apps/app_softhangup.c
+++ b/apps/app_softhangup.c
@@ -47,13 +47,15 @@ static int softhangup_exec(struct ast_channel *chan, void *data)
 		return 0;
 	}
 	LOCAL_USER_ADD(u);
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while (c) {
 		if (!strcasecmp(c->name, data)) {
 			ast_softhangup(c, AST_SOFTHANGUP_EXPLICIT);
+			ast_mutex_unlock(&c->lock);
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	LOCAL_USER_REMOVE(u);
 
diff --git a/apps/app_zapscan.c b/apps/app_zapscan.c
index ab87f592c..58a456f38 100755
--- a/apps/app_zapscan.c
+++ b/apps/app_zapscan.c
@@ -54,17 +54,18 @@ LOCAL_USER_DECL;
 
 #define CONF_SIZE 160
 
-static struct ast_channel *get_zap_channel(int num) {
+static struct ast_channel *get_zap_channel_locked(int num) {
 	struct ast_channel *c=NULL;
 	char name[80];
 
 	snprintf(name,sizeof(name),"Zap/%d-1",num);
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, name)) {
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (c)
 		return c;
@@ -293,43 +294,44 @@ static int conf_exec(struct ast_channel *chan, void *data)
                 ast_answer(chan);
 
         for (;;) {
-		if (ast_waitfor(chan, 100) < 0)
-			break;
-		f = ast_read(chan);
-		if (!f)
-			break;
-		if ((f->frametype == AST_FRAME_DTMF) && (f->subclass == '*')) {
+			if (ast_waitfor(chan, 100) < 0)
+				break;
+			
+			f = ast_read(chan);
+			if (!f)
+				break;
+			if ((f->frametype == AST_FRAME_DTMF) && (f->subclass == '*')) {
+				ast_frfree(f);
+				break;
+			}
 			ast_frfree(f);
-			break;
-		}
-		ast_frfree(f);
-		ichan = NULL;
-		if(input) {
-			ichan = get_zap_channel(input);
-			input = 0;
-		}
-
-		tempchan = ichan ? ichan : ast_channel_walk(tempchan);
-		
-		
-		if ( !tempchan && !lastchan )
-			break;
-		if ( tempchan && tempchan->type && (!strcmp(tempchan->type, "Zap")) && (tempchan != chan) ) {
-			ast_verbose(VERBOSE_PREFIX_3 "Zap channel %s is in-use, monitoring...\n", tempchan->name);
-			strcpy(confstr, tempchan->name);
-			if ((tmp = strchr(confstr,'-'))) {
-				*tmp = '\0';
+			ichan = NULL;
+			if(input) {
+				ichan = get_zap_channel_locked(input);
+				input = 0;
 			}
-			confno = atoi(strchr(confstr,'/') + 1);
-			ast_stopstream(chan);
-			ast_say_number(chan, confno, AST_DIGIT_ANY, chan->language, (char *) NULL);
-			res = conf_run(chan, confno, confflags);
-			if (res<0) break;
-			input = res;
-		}
-		lastchan = tempchan;
+	
+			tempchan = ichan ? ichan : ast_channel_walk_locked(tempchan);
+			
+			
+			if ( !tempchan && !lastchan )
+				break;
+			if ( tempchan && tempchan->type && (!strcmp(tempchan->type, "Zap")) && (tempchan != chan) ) {
+				ast_verbose(VERBOSE_PREFIX_3 "Zap channel %s is in-use, monitoring...\n", tempchan->name);
+				strcpy(confstr, tempchan->name);
+				ast_mutex_unlock(&tempchan->lock);
+				if ((tmp = strchr(confstr,'-'))) {
+					*tmp = '\0';
+				}
+				confno = atoi(strchr(confstr,'/') + 1);
+				ast_stopstream(chan);
+				ast_say_number(chan, confno, AST_DIGIT_ANY, chan->language, (char *) NULL);
+				res = conf_run(chan, confno, confflags);
+				if (res<0) break;
+				input = res;
+			}
+			lastchan = tempchan;
         }
-
         LOCAL_USER_REMOVE(u);
         return res;
 }
diff --git a/channel.c b/channel.c
index 8d23fca78..896fa8998 100755
--- a/channel.c
+++ b/channel.c
@@ -444,12 +444,15 @@ void ast_channel_undefer_dtmf(struct ast_channel *chan)
 		chan->deferdtmf = 0;
 }
 
-struct ast_channel *ast_channel_walk(struct ast_channel *prev)
+struct ast_channel *ast_channel_walk_locked(struct ast_channel *prev)
 {
+	/* Returns next channel (locked) */
 	struct ast_channel *l, *ret=NULL;
 	ast_mutex_lock(&chlock);
 	l = channels;
 	if (!prev) {
+		if (l)
+			ast_mutex_lock(&l->lock);
 		ast_mutex_unlock(&chlock);
 		return l;
 	}
@@ -458,6 +461,8 @@ struct ast_channel *ast_channel_walk(struct ast_channel *prev)
 			ret = l->next;
 		l = l->next;
 	}
+	if (ret)
+		ast_mutex_lock(&ret->lock);
 	ast_mutex_unlock(&chlock);
 	return ret;
 	
@@ -527,6 +532,12 @@ void ast_channel_free(struct ast_channel *chan)
 	}
 	if (!cur)
 		ast_log(LOG_WARNING, "Unable to find channel in list\n");
+	else {
+		/* Lock and unlock the channel just to be sure nobody
+		   has it locked still */
+		ast_mutex_lock(&cur->lock);
+		ast_mutex_unlock(&cur->lock);
+	}
 	if (chan->pvt->pvt)
 		ast_log(LOG_WARNING, "Channel '%s' may not have been hung up properly\n", chan->name);
 
@@ -1798,15 +1809,16 @@ int ast_parse_device_state(char *device)
 	char *cut;
 	struct ast_channel *chan;
 
-	chan = ast_channel_walk(NULL);
+	chan = ast_channel_walk_locked(NULL);
 	while (chan) {
 		strncpy(name, chan->name, sizeof(name)-1);
+		ast_mutex_unlock(&chan->lock);
 		cut = strchr(name,'-');
 		if (cut)
 		        *cut = 0;
 		if (!strcmp(name, device))
 		        return AST_DEVICE_INUSE;
-		chan = ast_channel_walk(chan);
+		chan = ast_channel_walk_locked(chan);
 	}
 	return AST_DEVICE_UNKNOWN;
 }
diff --git a/channels/chan_mgcp.c b/channels/chan_mgcp.c
index 5b7d0cf40..ea299187c 100755
--- a/channels/chan_mgcp.c
+++ b/channels/chan_mgcp.c
@@ -1764,6 +1764,8 @@ static int reqprep(struct mgcp_request *req, struct mgcp_endpoint *p, char *verb
 {
 	memset(req, 0, sizeof(struct mgcp_request));
 	oseq++;
+	if (oseq > 999999999)
+		oseq = 1;
 	init_req(p, req, verb);
 	return 0;
 }
diff --git a/cli.c b/cli.c
index a48ce4b7e..9a23cb6ec 100755
--- a/cli.c
+++ b/cli.c
@@ -291,13 +291,14 @@ static int handle_chanlist(int fd, int argc, char *argv[])
 	int numchans = 0;
 	if (argc != 2)
 		return RESULT_SHOWUSAGE;
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	ast_cli(fd, FORMAT_STRING2, "Channel", "Context", "Extension", "Pri", "State", "Appl.", "Data");
 	while(c) {
 		ast_cli(fd, FORMAT_STRING, c->name, c->context, c->exten, c->priority, ast_state2str(c->_state),
 		c->appl ? c->appl : "(None)", c->data ? ( !ast_strlen_zero(c->data) ? c->data : "(Empty)" ): "(None)");
 		numchans++;
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	ast_cli(fd, "%d active channel(s)\n", numchans);
 	return RESULT_SUCCESS;
@@ -335,14 +336,16 @@ static int handle_softhangup(int fd, int argc, char *argv[])
 	struct ast_channel *c=NULL;
 	if (argc != 3)
 		return RESULT_SHOWUSAGE;
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, argv[2])) {
 			ast_cli(fd, "Requested Hangup on channel '%s'\n", c->name);
 			ast_softhangup(c, AST_SOFTHANGUP_EXPLICIT);
+			ast_mutex_unlock(&c->lock);
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) 
 		ast_cli(fd, "%s is not a known channel\n", argv[2]);
@@ -438,17 +441,20 @@ static int handle_debugchan(int fd, int argc, char *argv[])
 	struct ast_channel *c=NULL;
 	if (argc != 3)
 		return RESULT_SHOWUSAGE;
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, argv[2])) {
 			c->fin |= 0x80000000;
 			c->fout |= 0x80000000;
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
-	if (c)
+	if (c) {
 		ast_cli(fd, "Debugging enabled on channel %s\n", c->name);
+		ast_mutex_unlock(&c->lock);
+	}
 	else
 		ast_cli(fd, "No such channel %s\n", argv[2]);
 	return RESULT_SUCCESS;
@@ -459,18 +465,20 @@ static int handle_nodebugchan(int fd, int argc, char *argv[])
 	struct ast_channel *c=NULL;
 	if (argc != 4)
 		return RESULT_SHOWUSAGE;
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, argv[3])) {
 			c->fin &= 0x7fffffff;
 			c->fout &= 0x7fffffff;
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
-	if (c)
+	if (c) {
 		ast_cli(fd, "Debugging disabled on channel %s\n", c->name);
-	else
+		ast_mutex_unlock(&c->lock);
+	} else
 		ast_cli(fd, "No such channel %s\n", argv[2]);
 	return RESULT_SUCCESS;
 }
@@ -482,7 +490,7 @@ static int handle_showchan(int fd, int argc, char *argv[])
 	struct ast_channel *c=NULL;
 	if (argc != 3)
 		return RESULT_SHOWUSAGE;
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, argv[2])) {
 			ast_cli(fd, 
@@ -519,10 +527,11 @@ static int handle_showchan(int fd, int argc, char *argv[])
 	c->context, c->exten, c->priority, c->callgroup, c->pickupgroup, ( c->appl ? c->appl : "(N/A)" ),
 	( c-> data ? (!ast_strlen_zero(c->data) ? c->data : "(Empty)") : "(None)"),
 	c->stack, (c->blocking ? c->blockproc : "(Not Blocking)"));
-	
+		ast_mutex_unlock(&c->lock);
 		break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) 
 		ast_cli(fd, "%s is not a known channel\n", argv[2]);
@@ -533,15 +542,22 @@ static char *complete_ch(char *line, char *word, int pos, int state)
 {
 	struct ast_channel *c;
 	int which=0;
-	c = ast_channel_walk(NULL);
+	char *ret;
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strncasecmp(word, c->name, strlen(word))) {
 			if (++which > state)
 				break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
-	return c ? strdup(c->name) : NULL;
+	if (c) {
+		ret = strdup(c->name);
+		ast_mutex_unlock(&c->lock);
+	} else
+		ret = NULL;
+	return ret;
 }
 
 static char *complete_fn(char *line, char *word, int pos, int state)
diff --git a/include/asterisk/channel.h b/include/asterisk/channel.h
index e420a1982..baae96213 100755
--- a/include/asterisk/channel.h
+++ b/include/asterisk/channel.h
@@ -624,8 +624,9 @@ int ast_recvchar(struct ast_channel *chan, int timeout);
  * \param prev where you want to start in the channel list
  * Browse the channels currently in use 
  * Returns the next channel in the list, NULL on end.
+ * If it returns a channel, that channel *has been locked*!
  */
-struct ast_channel *ast_channel_walk(struct ast_channel *prev);
+struct ast_channel *ast_channel_walk_locked(struct ast_channel *prev);
 
 //! Waits for a digit
 /*! 
diff --git a/manager.c b/manager.c
index ed94d80ce..53dcf6f09 100755
--- a/manager.c
+++ b/manager.c
@@ -376,18 +376,20 @@ static int action_hangup(struct mansession *s, struct message *m)
 		astman_send_error(s, m, "No channel specified");
 		return 0;
 	}
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, name)) {
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) {
 		astman_send_error(s, m, "No such channel");
 		return 0;
 	}
 	ast_softhangup(c, AST_SOFTHANGUP_EXPLICIT);
+	ast_mutex_unlock(&c->lock);
 	astman_send_ack(s, m, "Channel Hungup");
 	return 0;
 }
@@ -399,7 +401,7 @@ static int action_status(struct mansession *s, struct message *m)
 	struct ast_channel *c;
 	char bridge[256];
 	astman_send_ack(s, m, "Channel status will follow");
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
         if (id && strlen(id))
                 snprintf(idText,256,"ActionID: %s\r\n",id);
 	while(c) {
@@ -436,7 +438,8 @@ static int action_status(struct mansession *s, struct message *m)
 			c->name, c->callerid ? c->callerid : "<unknown>", 
 			ast_state2str(c->_state), bridge, c->uniqueid, idText);
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	ast_cli(s->fd,
 	"Event: StatusComplete\r\n"
@@ -688,18 +691,20 @@ static int action_timeout(struct mansession *s, struct message *m)
 		astman_send_error(s, m, "No timeout specified");
 		return 0;
 	}
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, name)) {
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) {
 		astman_send_error(s, m, "No such channel");
 		return 0;
 	}
 	ast_channel_setwhentohangup(c, timeout);
+	ast_mutex_unlock(&c->lock);
 	astman_send_ack(s, m, "Timeout Set");
 	return 0;
 }
diff --git a/pbx.c b/pbx.c
index ef5964fc0..11f2dea45 100755
--- a/pbx.c
+++ b/pbx.c
@@ -3592,15 +3592,21 @@ int ast_async_goto(struct ast_channel *chan, char *context, char *exten, int pri
 int ast_async_goto_by_name(char *channame, char *context, char *exten, int priority)
 {
 	struct ast_channel *chan;
-	chan = ast_channel_walk(NULL);
+	int res = -1;
+
+	chan = ast_channel_walk_locked(NULL);
 	while(chan) {
 		if (!strcasecmp(channame, chan->name))
 			break;
-		chan = ast_channel_walk(chan);
+		ast_mutex_unlock(&chan->lock);
+		chan = ast_channel_walk_locked(chan);
 	}
-	if (chan)
-		return ast_async_goto(chan, context, exten, priority);
-	return -1;
+	
+	if (chan) {
+		res = ast_async_goto(chan, context, exten, priority);
+		ast_mutex_unlock(&chan->lock);
+	}
+	return res;
 }
 
 static void ext_strncpy(char *dst, char *src, int len)
diff --git a/res/res_monitor.c b/res/res_monitor.c
index 22e365d08..3d7217090 100755
--- a/res/res_monitor.c
+++ b/res/res_monitor.c
@@ -333,12 +333,13 @@ static int start_monitor_action(struct mansession *s, struct message *m)
 		astman_send_error(s, m, "No channel specified");
 		return 0;
 	}
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, name)) {
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) {
 		astman_send_error(s, m, "No such channel");
@@ -360,6 +361,7 @@ static int start_monitor_action(struct mansession *s, struct message *m)
 			return 0;
 		}
 	}
+	ast_mutex_unlock(&c->lock);
 	astman_send_ack(s, m, "Started monitoring channel");
 	return 0;
 }
@@ -368,22 +370,26 @@ static int stop_monitor_action(struct mansession *s, struct message *m)
 {
 	struct ast_channel *c = NULL;
 	char *name = astman_get_header(m, "Channel");
+	int res;
 	if((!name)||(!strlen(name))) {
 		astman_send_error(s, m, "No channel specified");
 		return 0;
 	}
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, name)) {
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) {
 		astman_send_error(s, m, "No such channel");
 		return 0;
 	}
-	if( ast_monitor_stop( c, 1 ) ) {
+	res = ast_monitor_stop( c, 1 );
+	ast_mutex_unlock(&c->lock);
+	if( res ) {
 		astman_send_error(s, m, "Could not stop monitoring channel");
 		return 0;
 	}
@@ -404,12 +410,13 @@ static int change_monitor_action(struct mansession *s, struct message *m)
 		astman_send_error(s, m, "No filename specified");
 		return 0;
 	}
-	c = ast_channel_walk(NULL);
+	c = ast_channel_walk_locked(NULL);
 	while(c) {
 		if (!strcasecmp(c->name, name)) {
 			break;
 		}
-		c = ast_channel_walk(c);
+		ast_mutex_unlock(&c->lock);
+		c = ast_channel_walk_locked(c);
 	}
 	if (!c) {
 		astman_send_error(s, m, "No such channel");
diff --git a/res/res_parking.c b/res/res_parking.c
index 29b63684c..e63f490cb 100755
--- a/res/res_parking.c
+++ b/res/res_parking.c
@@ -737,7 +737,7 @@ int ast_pickup_call(struct ast_channel *chan)
 {
 	struct ast_channel *cur;
 	int res = -1;
-	cur = ast_channel_walk(NULL);
+	cur = ast_channel_walk_locked(NULL);
 	while(cur) {
 		if (!cur->pbx && 
 			(cur != chan) &&
@@ -746,7 +746,8 @@ int ast_pickup_call(struct ast_channel *chan)
 			 (cur->_state == AST_STATE_RING))) {
 			 	break;
 		}
-		cur = ast_channel_walk(cur);
+		ast_mutex_unlock(&cur->lock);
+		cur = ast_channel_walk_locked(cur);
 	}
 	if (cur) {
 		ast_log(LOG_DEBUG, "Call pickup on chan '%s' by '%s'\n",cur->name, chan->name);
@@ -759,6 +760,7 @@ int ast_pickup_call(struct ast_channel *chan)
 		res = ast_channel_masquerade(cur, chan);
 		if (res)
 			ast_log(LOG_WARNING, "Unable to masquerade '%s' into '%s'\n", chan->name, cur->name);		/* Done */
+		ast_mutex_unlock(&cur->lock);
 	} else	{
 		ast_log(LOG_DEBUG, "No call pickup possible...\n");
 	}