Re: [BUG] ptraced process waiting on syscall may return kernelinternal errnos

From: Benjamin Herrenschmidt
Date: Wed Jun 13 2007 - 19:19:23 EST

On Wed, 2007-06-13 at 16:01 -0700, Roland McGrath wrote:
> > What about something like:
> >
> > do {
> > rm_from_queue_full(&mask, &t->pending);
> > - recalc_sigpending_and_wake(t);
> > t = next_thread(t);
> > } while (t != current);
> > + recalc_sigpending();
> There is no need for the +, just the -. The calling thread is the one
> where know there is certainly no perturbation of behavior due to leaving
> TIF_SIGPENDING set rather than clearing it. It's just going to exit the
> syscall and deal with signal state properly on the way out either way.
> Doing recalc_sigpending is an unnecessary optimization of the corner case.

Fair enough. I'll cook a patch for that one when I'm at work.

> > So at the end of the day, easier to test it inside dequeue_signal().
> Before completely revamping the whole set of entrypoints to be saner all
> around, yes.

btw, another interesting grep is to see how tweak TIF_SIGPENDING by
hand ... there's some scary bits in the tty code too...


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