From: Andi Kleen <ak@suse.de>
Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
To: "Satyam Sharma" <satyam.sharma@gmail.com>
Subject: Re: [patch] i386/x86_64: smp_call_function locking inconsistency
Date: Fri, 8 Jun 2007 21:43:51 +0200
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Cc: "Heiko Carstens" <heiko.carstens@de.ibm.com>,
       "Jan Glauber" <jan.glauber@de.ibm.com>,
       "David Miller" <davem@davemloft.net>, akpm@osdl.org, mingo@elte.hu,
       schwidefsky@de.ibm.com, linux-kernel@vger.kernel.org,
       "Alan Cox" <alan@redhat.com>
References: <20070208203210.GB9798@osiris.ibm.com> <20070607162743.GA9433@osiris.ibm.com> <a781481a0706070954l636d752am82ef7ca9703788aa@mail.gmail.com>
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> Indeed -- this was doubly problematic because the un-safeness
> was because of smp_processor_id() as well as the (eventual)
> access of cpu_online_map (via smp_call_function() ->
> num_online_cpus()) ... thanks for letting me know about this.

CPU hotplug is changed to use the freezer anyways. It is known
that the current handling of these maps in preempt has various holes and this
little case here won't make it overall much worse.

-Andi
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