[PATCH] tty: amiserial: fix broken TIOCMIWAIT
From: Johan Hovold
Date: Fri Sep 11 2026 - 05:09:57 EST
A change replacing interruptible_sleep_on() inadvertently broke the
TIOCMIWAIT implementation which now immediately returns -EIO (unless
there is a racing modem status update).
Replace the old hangup (and signal) detection with a check for the
TTY_IO_ERROR flag which is set on hangup.
Fixes: 591cee0a3563 ("tty/amiserial: avoid interruptible_sleep_on")
Reported-by: sashiko-bot@xxxxxxxxxx
Link: https://lore.kernel.org/20260910132029.D80801F00898@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # 3.14
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/tty/amiserial.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 28af0fd98181..60f6060b893d 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -1138,11 +1138,6 @@ static int rs_ioctl(struct tty_struct *tty,
local_irq_save(flags);
cnow = info->icount; /* atomic copy */
local_irq_restore(flags);
- if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
- cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
- ret = -EIO; /* no change => error */
- break;
- }
if ( ((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
((arg & TIOCM_CD) && (cnow.dcd != cprev.dcd)) ||
@@ -1150,6 +1145,10 @@ static int rs_ioctl(struct tty_struct *tty,
ret = 0;
break;
}
+ if (tty_io_error(tty)) {
+ ret = -EIO;
+ break;
+ }
schedule();
/* see if a signal did it */
if (signal_pending(current)) {
--
2.55.0