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Message-ID: <m2ehzcdkf2.fsf@firstfloor.org>
Date: Mon, 19 Sep 2011 19:20:17 -0700
From: Andi Kleen <andi@...stfloor.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Christoph Lameter <cl@...ux.com>
Subject: Re: [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write()
Steven Rostedt <rostedt@...dmis.org> writes:
> I just found out that the this_cpu_*() functions do not perform the
> test to see if the usage is in atomic or not. Thus, the blind
> conversion of the per_cpu(*, smp_processor_id()) and the get_cpu_var()
> code to this_cpu_*() introduce the regression to detect the hard
> to find case where a per cpu variable is used in preempt code that
> migrates and causes bugs.
Didn't preempt-rt recently get changed to not migrate in kernel-preempt
regions. How about just fixing the normal preemption to not do this
either.
Then all these complications wouldn't be necessary and a whole lot
of code related to this could be removed too, and you would still
have less bugs.
-Andi
--
ak@...ux.intel.com -- Speaking for myself only
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