Re: [RFC] tty: Always allow tcflow(TCOON) to unwedge terminal

From: Greg Kroah-Hartman
Date: Wed Sep 10 2014 - 20:04:37 EST


On Wed, Sep 10, 2014 at 05:28:19PM -0400, Peter Hurley wrote:
> 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.

I don't see the benifit here, what are you trying to solve? Sending one
extra tcflow command?

thanks,

greg k-h
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