n_tty: Eliminate char tests from IXANY restart test

Relocate the IXANY restart tty test to code paths where the
the received char is not START_CHAR, STOP_CHAR, INTR_CHAR,
QUIT_CHAR or SUSP_CHAR.

Fixes the condition when ISIG if off and one of INTR_CHAR,
QUIT_CHAR or SUSP_CHAR does not restart i/o.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/n_tty.c

@@ -1270,13 +1270,6 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 		return;
 	}
 
-	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
-	    I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
-	    c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
-		start_tty(tty);
-		process_echoes(tty);
-	}
-
 	/*
 	 * If the previous character was LNEXT, or we know that this
 	 * character is not one of the characters that we'll have to
@@ -1285,6 +1278,13 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 	 */
 	if (!test_bit(c, ldata->char_map) || ldata->lnext) {
 		ldata->lnext = 0;
+
+		if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
+		    I_IXANY(tty)) {
+			start_tty(tty);
+			process_echoes(tty);
+		}
+
 		parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
 		if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
 			/* beep if no space */
@@ -1331,6 +1331,11 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 		}
 	}
 
+	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
+		start_tty(tty);
+		process_echoes(tty);
+	}
+
 	if (c == '\r') {
 		if (I_IGNCR(tty))
 			return;