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Date: Mon, 27 Oct 2008 13:38:16 -0400 From: "Mike Frysinger" <vapier.adi@...il.com> To: "Jan Kratochvil" <jan.kratochvil@...hat.com> Cc: "Mike Frysinger" <vapier@...too.org>, linux-kernel@...r.kernel.org Subject: Re: inconsistent behavior with ptrace(TRACEME) and fork/exec On Mon, Oct 27, 2008 at 10:56, Jan Kratochvil wrote: > On Wed, 19 Jul 2006 21:18:29 +0200, Mike Frysinger wrote: >> my understanding is that if a parent forks and the child does >> a ptrace(TRACEME) right before doing an exec(), the kernel should always >> halt it and wait indefinitely for the parent to start ptracing it. > > Yes, just the parent must process the event (signal). In your testcase the > parent finished before the signal could be delivered. If the tracer exits the > tracee's tracing is finished and it continues freely. no signal should have been generated. the child should have gone straight to the exec and waited for the parent to process it. >> unfortunately, this behavior seems to be unreliable. > > Fixed the races in your code and I do not see there any problem, do you? > The ptrace problems/testsuite is being maintained at: > http://sourceware.org/systemtap/wiki/utrace/tests there is no race condition ... it's using vfork here remember ? it is impossible for the parent to have executed anything after the vfork() before the child made it into the exec() and gone to sleep -mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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