Re: [PATCH v2 2/3] tty: Add lookahead param to receive_buf

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Fri, Apr 08, 2022 at 03:34:27PM +0300, Ilpo Järvinen wrote:
> On Fri, 8 Apr 2022, Andy Shevchenko wrote:
> > On Fri, Apr 08, 2022 at 02:39:53PM +0300, Ilpo Järvinen wrote:

...

> > > +		if (c == STOP_CHAR(tty)) {
> > > +			if (!lookahead_done)
> > 
> > But now it can be as below
> > 
> > 		if (c == STOP_CHAR(tty) && !lookahead_done)
> > 
> > > +				stop_tty(tty);
> > > +		} else if ((c == START_CHAR(tty) && !lookahead_done) ||
> > >  			 (tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) &&
> > >  			  c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
> > >  			  c != SUSP_CHAR(tty))) {
> 
> Are you sure about this? ...If I make that change to the first if, the 
> second part of the else if's condition get a chance it didn't have 
> previously.

Oh, indeed. This will give a chance to the rest of the second conditional to be
triggered because of ||.

> What I'd like to do here is to take advantage of the function that was 
> added:
> 
> 		if (!n_tty_receive_char_flow_ctrl(tty, c) &&
> 		    tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) &&
>         	    c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
> 	            c != SUSP_CHAR(tty))) {
> 			start_tty(tty);
> 			process_echoes(tty);
> 		}
> ...but it will change STOP_CHAR vs START_CHAR precedence for the case 
> where they're the same characters. I don't know if it matters.

No idea of impact of such change.

-- 
With Best Regards,
Andy Shevchenko