Merged revisions 323040 via svnmerge from
[asterisk/asterisk.git] / channels / chan_sip.c
index 30125bb..cb9b8b2 100644 (file)
@@ -7275,12 +7275,19 @@ static struct ast_frame *sip_read(struct ast_channel *ast)
 
        /* If we detect a CNG tone and fax detection is enabled then send us off to the fax extension */
        if (faxdetected && ast_test_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT_CNG)) {
-               ast_channel_lock(ast);
                if (strcmp(ast->exten, "fax")) {
                        const char *target_context = S_OR(ast->macrocontext, ast->context);
+                       /* We need to unlock 'ast' here because
+                        * ast_exists_extension has the potential to start and
+                        * stop an autoservice on the channel. Such action is
+                        * prone to deadlock if the channel is locked.
+                        */
+                       sip_pvt_unlock(p);
                        ast_channel_unlock(ast);
                        if (ast_exists_extension(ast, target_context, "fax", 1,
                                S_COR(ast->caller.id.number.valid, ast->caller.id.number.str, NULL))) {
+                               ast_channel_lock(ast);
+                               sip_pvt_lock(p);
                                ast_verbose(VERBOSE_PREFIX_2 "Redirecting '%s' to fax extension due to CNG detection\n", ast->name);
                                pbx_builtin_setvar_helper(ast, "FAXEXTEN", ast->exten);
                                if (ast_async_goto(ast, target_context, "fax", 1)) {
@@ -7288,10 +7295,10 @@ static struct ast_frame *sip_read(struct ast_channel *ast)
                                }
                                fr = &ast_null_frame;
                        } else {
+                               ast_channel_lock(ast);
+                               sip_pvt_lock(p);
                                ast_log(LOG_NOTICE, "FAX CNG detected but no fax extension\n");
                        }
-               } else {
-                       ast_channel_unlock(ast);
                }
        }