Paul Mackerras <[EMAIL PROTECTED]> wrote:
>
> Andrew Morton writes:
>
> > hm, a PPP fix. We seem to need some of those lately.
> >
> > Paul, does this look sane?
>
> /me pages in 7 year old code...
>
> > @@ -516,6 +516,8 @@ static void ppp_async_process(unsigned l
> > /* try to push more stuff out */
> > if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap))
> > ppp_output_wakeup(&ap->chan);
> > + else if (test_bit(XMIT_FULL, &ap->xmit_flags))
> > + ppp_asynctty_wakeup(ap->tty);
>
> ppp_asynctty_wakeup is supposed to be called by the serial driver when
> it can take more output. It's slightly bogus having ppp_async call it
> itself whether or not the serial driver can take more output at the
> moment, but I suppose it won't hurt. I would really like to know the
> precise circumstances where we need this fake wakeup though. Is the
> serial driver failing to give us a wakeup call where it should, or is
> ppp_async ignoring a wakeup for some reason?
>
> I think the same effect could be achieved without an extra trip
> through tasklet_schedule et al. by making those lines look like this
> (untested):
>
> if ((test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
> test_bit(XMIT_FULL, &ap->xmit_flags)) && ppp_async_push(ap))
> ppp_output_wakeup(&ap->chan);
>
> so that ppp_async_push gets called if either XMIT_WAKEUP or XMIT_FULL
> is set.
>
> This is all relying on getting some input to kick off more output when
> the wakeup gets missed, though. That's a reasonable workaround in most
> situations, I guess, but I'd really like to know why the wakeup is
> getting missed.
>
(xeb, on this bug please respond via email using reply-to-all rather than
via the bugzilla web form).
xeb has said:
in this construction:
if ((test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
test_bit(XMIT_FULL, &ap->xmit_flags)) && ppp_async_push(ap))
ppp_output_wakeup(&ap->chan);
if ppp_async_push() doesn't send any data i.e. XMIT_FULL is set then all
(transfer) hangs up while somebody push again, for instance lcp-echo.
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