Merged revisions 317837 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

........
  r317837 | russell | 2011-05-06 14:24:11 -0500 (Fri, 06 May 2011) | 11 lines
  
  Fix a crash in the MySQL() application.
  
  This code was not handling channel datastores safely.  The channel
  must be locked.
  
  (closes issue #17964)
  Reported by: wuwu
  Patches:
        issue17964_addon_1.6.2_svn.patch uploaded by seanbright (license 71)
  Tested by: wuwu
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@317843 65c4cc65-6c06-0410-ace0-fbb531ad65f3

addons/app_mysql.c

@@ -546,7 +546,10 @@ static int MYSQL_exec(struct ast_channel *chan, const char *data)
 	result = 0;
 
 	if (autoclear) {
-		struct ast_datastore *mysql_store = ast_channel_datastore_find(chan, &mysql_ds_info, NULL);
+		struct ast_datastore *mysql_store = NULL;
+
+		ast_channel_lock(chan);
+		mysql_store = ast_channel_datastore_find(chan, &mysql_ds_info, NULL);
 		if (!mysql_store) {
 			if (!(mysql_store = ast_datastore_alloc(&mysql_ds_info, NULL))) {
 				ast_log(LOG_WARNING, "Unable to allocate new datastore.\n");
@@ -555,6 +558,7 @@ static int MYSQL_exec(struct ast_channel *chan, const char *data)
 				ast_channel_datastore_add(chan, mysql_store);
 			}
 		}
+		ast_channel_unlock(chan);
 	}
 	ast_mutex_lock(&_mysql_mutex);