Messages in this thread |  | | Date | Tue, 27 Aug 2002 11:39:57 -0400 | From | Daniel Jacobowitz <> | Subject | Re: [patch] O(1) sys_exit(), threading, scalable-exit-2.5.31-A6 |
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On Tue, Aug 20, 2002 at 04:36:19PM +0200, Ingo Molnar wrote: > > the attached patch ontop of BK-curr fixes the ptrace wait4() anomaly that > can be observed in any previous Linux kernel i could get my hands at. So > in fact ->ptrace_children, besides being a speedup, also fixed a bug that > couldnt be fixed in any satisfactory way before. > > Ingo > > --- linux/kernel/exit.c.orig Tue Aug 20 16:28:57 2002 > +++ linux/kernel/exit.c Tue Aug 20 16:30:13 2002 > @@ -731,7 +731,7 @@ > tsk = next_thread(tsk); > } while (tsk != current); > read_unlock(&tasklist_lock); > - if (flag) { > + if (flag || !list_empty(¤t->ptrace_children)) { > retval = 0; > if (options & WNOHANG) > goto end_wait4;
Ingo,
At this point your ptrace changes have completely broken both _TRACEME/exec and _ATTACH debugging. If an attached process finishes while a debugger is attached, its parent no longer gets the proper wait result for it:
wait4(-1, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WNOHANG|WUNTRACED, NULL) = 478 wait4(-1, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WNOHANG|WUNTRACED, NULL) = 478 wait4(-1, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WNOHANG|WUNTRACED, NULL) = 478 wait4(-1, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WNOHANG|WUNTRACED, NULL) = 478 wait4(-1, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WNOHANG|WUNTRACED, NULL) = 478 wait4(-1, [WIFEXITED(s) && WEXITSTATUS(s) == 0], WNOHANG|WUNTRACED, NULL) = 478
etc. It is never removed from the list. _TRACEME/exec debugging appears to have the same problem but it's harder to tell, since one can not strace GDB in 2.5 without the patch I posted here two weeks ago. If you don't have a chance to look at this I'll investigate later today.
-- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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