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Re: lin-lwp and exiting threads
On Tue, Aug 26, 2003 at 02:43:23PM -0400, J. Johnston wrote:
> Daniel Jacobowitz wrote:
> >On Tue, Aug 26, 2003 at 01:51:35PM -0400, Daniel Jacobowitz wrote:
> >
> >>Hi Jeff,
> >>
> >>I'm doing some work in lin-lwp.c and I saw this bit you recently
> >>committed:
> >>
> >>+ /* Check if the current LWP has previously exited. For nptl
> >>threads,
> >>+ there is no exit signal issued for LWPs that are not the
> >>+ main thread so we should check whenever the thread is stopped.
> >>*/
> >>+ if (!lin_lwp_thread_alive (lp->ptid))
> >>+ {
> >>+ if (in_thread_list (lp->ptid))
> >>+ {
> >>+ /* Core GDB cannot deal with us deleting the current
> >>+ thread. */
> >>+ if (!ptid_equal (lp->ptid, inferior_ptid))
> >>+ delete_thread (lp->ptid);
> >>+ printf_unfiltered ("[%s exited]\n",
> >>+ target_pid_to_str (lp->ptid));
> >>+ }
> >>+ if (debug_lin_lwp)
> >>+ fprintf_unfiltered (gdb_stdlog,
> >>+ "SWC: %s already exited.\n",
> >> target_pid_to_str (lp->ptid));
> >>
> >>
> >>This is right after waitpid has returned a non-exiting stopped status for
> >>lp->ptid. Were you just being thorough, or do you have some reason to
> >>believe that waitpid would ever return WIFSTOPPED (status) and yet the
> >>thread would be dead?
> >
>
> In the early days of nptl, the kernel wasn't always doing what it was
> expected to. This appears to be leftover code as I attempted to ensure we
> caught the thread exiting one way or another.
>
> >
> >Also, there's:
> > pid = waitpid (GET_LWP (lp->ptid), &status, 0);
> > if (pid == -1 && errno == ECHILD)
> > {
> > pid = waitpid (GET_LWP (lp->ptid), &status, __WCLONE);
> > if (pid == -1 && errno == ECHILD)
> > {
> > /* The thread has previously exited. We need to delete it now
> > because in the case of NPTL threads, there won't be an
> > exit event unless it is the main thread. */
> > if (debug_lin_lwp)
> > fprintf_unfiltered (gdb_stdlog,
> > "SWC: %s exited.\n",
> > target_pid_to_str (lp->ptid));
> > delete_lwp (lp->ptid);
> > return 0;
> > }
> > }
> >
> >Is there some reason you don't also call delete_thread?
> >
>
> Hmm, appears to be an oversight on my part.
>
> Do you want to make these changes?
I'll take care of it, since I'm moving this code anyway. I just wanted
to check that I wasn't missing some Grand Design (TM).
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer