On Tue, Apr 26, 2022 at 10:48:40AM +0300, Ilpo Järvinen wrote:
> On Fri, 22 Apr 2022, Ilpo Järvinen wrote:
>
> > On Fri, 22 Apr 2022, Greg KH wrote:
> >
> > > > /* Returns true if c is consumed as flow-control character */
> > > > -static bool n_tty_receive_char_flow_ctrl(struct tty_struct *tty, unsigned char c)
> > > > +static bool n_tty_receive_char_flow_ctrl(struct tty_struct *tty, unsigned char c,
> > > > + bool lookahead_done)
> > > > {
> > > > if (!n_tty_is_char_flow_ctrl(tty, c))
> > > > return false;
> > > >
> > > > + if (lookahead_done)
> > > > + return true;
> > >
> > > Why would this function be called if this option was true?
> >
> > Agreed, it makes sense to move the check before call (and then I also
> > don't need to reorganize this function anymore).
>
> I think I want to renege on this. The reason is that on flow control char,
> two things must occur:
> a) it must not be treated as normal char
> b) if not yet processed, flow control actions need to be taken
>
> When the check is inside, return value of n_tty_receive_char_flow_ctrl
> decides a), and b) is kept internal to n_tty_receive_char_flow_ctrl().
>
> If I more that lookahead_done check into the caller domain, things get
> IMHO a lot more messy. Effectively, I have three options for the calling
> domain to chose from:
>
> if (I_IXON(tty)) {
> if (!lookahead_done) {
> if (n_tty_receive_char_flow_ctrl(tty, c))
> return;
> } else if (n_tty_is_char_flow_ctrl(tty, c)) {
> return;
> }
> }
>
> or
>
> if (I_IXON(tty)) {
> if ((!lookahead_done && n_tty_receive_char_flow_ctrl(tty, c)) ||
> (lookahead_done && n_tty_is_char_flow_ctrl(tty, c))) {
> return;
> }
>
> vs
>
> if (I_IXON(tty) && n_tty_receive_char_flow_ctrl(tty, c, lookahead_done))
> return;
>
> I heavily prefer that last option.
Ok, then document the heck out of it please.
greg k-h
