From: Frederic Weisbecker <fweisbec@gmail.com>
To: Will Deacon <will.deacon@arm.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Prasad <prasad@linux.vnet.ibm.com>,
Paul Mundt <lethal@linux-sh.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
"v2.6.33.." <stable@kernel.org>
Subject: Re: [PATCH 1/5] ptrace: Prepare to fix racy accesses on task breakpoints
Date: Wed, 13 Apr 2011 17:10:44 +0200 [thread overview]
Message-ID: <20110413151040.GC2277@nowhere> (raw)
In-Reply-To: <1302705258.4214.11.camel@e102144-lin.cambridge.arm.com>
On Wed, Apr 13, 2011 at 03:34:18PM +0100, Will Deacon wrote:
> > Returning -ERSCH there would mean that the task struct doesn't exist,
> > or something confusing like this. Which is not true: the task exists.
>
> Sure, we need a way of saying `you can't take a reference to the
> breakpoints for this task' without specifying why. So I guess -ESRCH is
> wrong but I don't know that -1 is correct either (then again, I'm not
> *too* bothered by it :).
-EBUSY perhaps? Well I took -1 by default...
>
> > OTOH, the caller, which is ptrace, needs to take a decision when he
> > can't take a reference to the breakpoints. The behaviour is
> > to act as if the process does not exist anymore, which is about to
> > happen for real but we anticipate because the task has reached a
> > state in its exiting path where we can't manipulate the breakpoints
> > anymore.
> >
> > So the rationale behind it is that -ERSCH is an interpretation
> > of the caller.
> >
> > Right?
>
> Yup.
>
> For this and the ARM patch:
>
> Acked-by: Will Deacon <will.deacon@arm.com>
Great! Thanks!
next prev parent reply other threads:[~2011-04-13 15:10 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-08 17:34 [PATCH 0/5] hw_breakpoints: Fix racy ptrace breakpoint acccesses Frederic Weisbecker
2011-04-08 17:34 ` [PATCH 1/5] ptrace: Prepare to fix racy accesses on task breakpoints Frederic Weisbecker
2011-04-11 10:47 ` Will Deacon
2011-04-12 17:54 ` Frederic Weisbecker
2011-04-13 14:34 ` Will Deacon
2011-04-13 15:10 ` Frederic Weisbecker [this message]
2011-04-25 17:37 ` Frederic Weisbecker
2011-05-04 20:28 ` [tip:perf/urgent] " tip-bot for Frederic Weisbecker
2011-04-08 17:34 ` [PATCH 2/5] x86, hw_breakpoints: Fix racy access to ptrace breakpoints Frederic Weisbecker
2011-05-04 20:28 ` [tip:perf/urgent] " tip-bot for Frederic Weisbecker
2011-04-08 17:34 ` [PATCH 3/5] powerpc, " Frederic Weisbecker
2011-04-22 13:16 ` Frederic Weisbecker
2011-04-22 13:16 ` Frederic Weisbecker
2011-04-24 8:04 ` K.Prasad
2011-04-24 8:04 ` K.Prasad
2011-05-04 20:29 ` [tip:perf/urgent] " tip-bot for Frederic Weisbecker
2011-04-08 17:34 ` [PATCH 4/5] arm, " Frederic Weisbecker
2011-05-04 20:29 ` [tip:perf/urgent] " tip-bot for Frederic Weisbecker
2011-04-08 17:34 ` [PATCH 5/5] sh, " Frederic Weisbecker
2011-04-11 16:28 ` Paul Mundt
2011-05-04 20:30 ` [tip:perf/urgent] " tip-bot for Frederic Weisbecker
2011-04-25 16:17 ` [PATCH 0/5] hw_breakpoints: Fix racy ptrace breakpoint acccesses Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2011-05-03 13:25 [GIT PULL] hw_breakpoint fixes Frederic Weisbecker
2011-05-03 13:25 ` [PATCH 1/5] ptrace: Prepare to fix racy accesses on task breakpoints Frederic Weisbecker
2011-05-04 6:31 ` Ingo Molnar
2011-05-04 18:22 ` Frederic Weisbecker
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