This patch changes user-space behavior (for the better) but I'm not sure
that it's consequence-free. Also, it might not be enough to unwedge the
terminal if the driver got its own flow control state mangled.
Thoughts?
--- >% ---
Subject: [RFC] tty: Always allow tcflow(TCOON) to unwedge terminal
If terminal flow has been stopped, the terminal can be unwedged
by:
tcflow(fd, TCOOFF);
tcflow(fd, TCOON);
This works because tcflow(TCOOFF) ensures that ->flow_stopped is set,
which allows tcflow(TCOON) to override the terminal flow state in
__start_tty().
Instead, allow unwedging with only:
tcflow(fd, TCOON);
by disregarding the existing ->flow_stopped state.
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/tty_ioctl.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 32cee97..c792088 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -1157,10 +1157,8 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
break;
case TCOON:
spin_lock_irq(&tty->flow_lock);
- if (tty->flow_stopped) {
- tty->flow_stopped = 0;
- __start_tty(tty);
- }
+ tty->flow_stopped = 0;
+ __start_tty(tty);
spin_unlock_irq(&tty->flow_lock);
break;
case TCIOFF:
--
2.1.0
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