quoted

. . . .seems like this might introduce a bug if we could get interrupted after

the

quoted

restore of the new_flags but before the second restore of old flags in such a
way such that the proper state of old_flags could change. I'm not comfortable
enough though with my understanding of interrupts and driver routines to be
certain one way or another. To be more specific, consider the case on just a
single processor system. If this strikes anyone else as a possible race
condition that could introduce a bug, then this is what we need to fix in
macserial.c's rs_write routine since this code can potentially happen.

I'm fairly certain it's a bug.  Good spotting.  The last restore_flags()
shouldn't be there.

--- macserial.c.ORIG    Wed Sep 29 02:05:14 1999
+++ macserial.c Wed Sep 29 02:05:31 1999

@@ -1381,7 +1381,6 @@
        if (info->xmit_cnt && !tty->stopped && !info->tx_stopped
            && !info->tx_active)
                transmit_chars(info);
-       restore_flags(flags);
        return ret;
 }

Takashi Oe