linux-kernel - Re: linux-next: add utrace tree

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Message-ID: <20100126220301.GG6567@basil.fritz.box>
Date:	Tue, 26 Jan 2010 23:03:01 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	tromey@...hat.com, Stephen Rothwell <sfr@...b.auug.org.au>,
	Kyle Moffett <kyle@...fetthome.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Peter Zijlstra <peterz@...radead.org>,
	Fr??d??ric Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	"Frank Ch. Eigler" <fche@...hat.com>, linux-next@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>, utrace-devel@...hat.com,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: linux-next: add utrace tree

> Simple example. Try to debug/strace strace ot gdb itself. Not trivial,
> you can't attach to strace's tracees. Recently I spent 2 days trying to
> understand why strace -f hangs. I was able to attach to strace, but
> I wasn't able to see what its tracees do.

But what would the semantics be inside the tracees even if you could?

> And, it was not possible to even trace strace until it hangs, with
> ptrace the tracee (strace) must stop to report the event and this
> shadowed the race.

"Shadowing the race" was the second surname of strace I thought anyways @)
Basically if you care about races never use strace in the first place.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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