From: Tejun Heo <tj@kernel.org>
To: rostedt@goodmis.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Randy Dunlap <randy.dunlap@oracle.com>,
Eric Dumazet <dada1@cosmosbay.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@suse.de>, stable <stable@kernel.org>
Subject: Re: [PATCH] modules fix incorrect percpu usage
Date: Wed, 31 Mar 2010 11:15:49 +0900 [thread overview]
Message-ID: <4BB2B055.1020807@kernel.org> (raw)
In-Reply-To: <1270001013.19685.6677.camel@gandalf.stny.rr.com>
On 03/31/2010 11:03 AM, Steven Rostedt wrote:
> I don't know. A possible "NULL pointer dereference" seems to me to be a
> pretty big user visible impact.
>
> I guess the question is, what's the risk of adding this change?
AFAICS, the risk is fairly low. per_cpu_ptr(pcpudest, cpu) is
SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))) which is just a fancy
way of saying "typeof(ptr)((unsigned long)(ptr) + per_cpu_offset(cpu))"
with enough obfuscation to prevent gcc from optimizing it incorrectly.
Thanks.
--
tejun
next prev parent reply other threads:[~2010-03-31 2:17 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-30 13:52 [PATCH] modules fix incorrect percpu usage Mathieu Desnoyers
2010-03-30 19:53 ` Andrew Morton
2010-03-30 20:24 ` Mathieu Desnoyers
2010-03-31 2:03 ` Steven Rostedt
2010-03-31 2:15 ` Tejun Heo [this message]
2010-03-31 1:49 ` Tejun Heo
-- strict thread matches above, loose matches on Subject: below --
2010-03-30 3:32 [PATCH -stable] " Mathieu Desnoyers
2010-03-30 3:36 ` [PATCH] " Mathieu Desnoyers
2010-03-30 13:20 ` Steven Rostedt
2010-03-30 13:50 ` Mathieu Desnoyers
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