res_fax.c: Add chan locked precondition comments.

Change-Id: Ic10ae434536bbf7fb7055d6ab36cc50b8748a4e7

res/res_fax.c

@@ -2880,11 +2880,17 @@ static struct fax_gateway *fax_gateway_new(struct ast_channel *chan, struct ast_
 	return gateway;
 }
 
-/*! \brief Create a fax session and start T.30<->T.38 gateway mode
+/*!
+ * \brief Create a fax session and start T.30<->T.38 gateway mode
+ *
  * \param gateway a fax gateway object
  * \param details fax session details
  * \param chan active channel
- * \return 0 on error 1 on success*/
+ *
+ * \pre chan is locked on entry
+ *
+ * \return 0 on error 1 on success
+ */
 static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session_details *details, struct ast_channel *chan)
 {
 	struct ast_fax_session *s;
@@ -2928,6 +2934,7 @@ static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session
 	return 0;
 }
 
+/*! \pre chan is locked on entry */
 static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_frame *f)
 {
 	struct ast_frame *fp;
@@ -2966,6 +2973,7 @@ static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, st
 	return fp;
 }
 
+/*! \pre chan is locked on entry */
 static struct ast_frame *fax_gateway_detect_v21(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
 {
 	struct ast_channel *other = (active == chan) ? peer : chan;
@@ -3002,12 +3010,17 @@ static int fax_gateway_indicate_t38(struct ast_channel *chan, struct ast_channel
 	}
 }
 
-/*! \brief T38 Gateway Negotiate t38 parameters
+/*!
+ * \brief T38 Gateway Negotiate t38 parameters
+ *
  * \param gateway gateway object
  * \param chan channel running the gateway
  * \param peer channel im bridged too
  * \param active channel the frame originated on
  * \param f the control frame to process
+ *
+ * \pre chan is locked on entry
+ *
  * \return processed control frame or null frame
  */
 static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
@@ -3250,7 +3263,8 @@ static void fax_gateway_framehook_destroy(void *data)
 	ao2_ref(gateway, -1);
 }
 
-/*! \brief T.30<->T.38 gateway framehook.
+/*!
+ * \brief T.30<->T.38 gateway framehook.
  *
  * Intercept packets on bridged channels and determine if a T.38 gateway is
  * required. If a gateway is required, start a gateway and handle T.38
@@ -3261,6 +3275,8 @@ static void fax_gateway_framehook_destroy(void *data)
  * \param event framehook event
  * \param data framehook data (struct fax_gateway *)
  *
+ * \pre chan is locked on entry
+ *
  * \return processed frame or NULL when f is NULL or a null frame
  */
 static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct ast_frame *f, enum ast_framehook_event event, void *data)
@@ -3491,9 +3507,9 @@ static int fax_gateway_attach(struct ast_channel *chan, struct ast_fax_session_d
 		.disable_inheritance = 1, /* Masquerade inheritance is handled through the datastore fixup */
 	};
 
-    	if (global_fax_debug) {
-        	details->option.debug = AST_FAX_OPTFLAG_TRUE;
-    	}
+	if (global_fax_debug) {
+		details->option.debug = AST_FAX_OPTFLAG_TRUE;
+	}
 
 	ast_string_field_set(details, result, "SUCCESS");
 	ast_string_field_set(details, resultstr, "gateway operation started successfully");