From: Pekka Enberg <penberg@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com,
tglx@linutronix.de, hpa@zytor.com, x86@kernel.org,
eric.dumazet@gmail.com, yinghai@kernel.org, brgerst@gmail.com,
gorcunov@gmail.com
Subject: Re: [PATCH UPDATED#3 04/16] x86: setup_local_APIC() must always be called with preemption disabled
Date: Thu, 09 Dec 2010 18:18:54 +0200 [thread overview]
Message-ID: <1291911534.29040.0.camel@jaguar> (raw)
In-Reply-To: <4D00B3B9.7060702@kernel.org>
On Thu, 2010-12-09 at 11:47 +0100, Tejun Heo wrote:
> setup_local_APIC() is used to setup local APIC early during CPU
> initialization and already assumes that preemption is disabled on
> entry. However, The function unnecessarily disables and enables
> preemption and uses smp_processor_id() multiple times in and out of
> the nested preemption disabled section. This gives the wrong
> impression that the function might be able to handle being called with
> preemption enabled and/or migrated to another processor in the middle.
>
> Make it clear that the function is always called with preemption
> disabled, drop the confusing preemption disable block and call
> smp_processor_id() once at the beginning of the function.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Yinghai Lu <yinghai@kernel.org>
> Cc: Cyrill Gorcunov <gorcunov@gmail.com>
> Cc: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
next prev parent reply other threads:[~2010-12-09 16:18 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-27 15:21 [PATCHSET] x86: unify x86_32 and 64 NUMA init paths, take#2 Tejun Heo
2010-11-27 15:21 ` [PATCH 01/16] x86: Kill unused static boot_cpu_logical_apicid in smpboot.c Tejun Heo
2010-11-27 15:21 ` [PATCH 02/16] x86: Rename x86_32 MAX_APICID to MAX_LOCAL_APIC Tejun Heo
2010-11-27 15:21 ` [PATCH 03/16] x86: Make default_send_IPI_mask_sequence/allbutself_logical() 32bit only Tejun Heo
2010-11-27 15:21 ` [PATCH 04/16] x86: Use local variable to cache smp_processor_id() in setup_local_APIC() Tejun Heo
2010-11-27 21:32 ` Cyrill Gorcunov
2010-11-30 16:17 ` [PATCH UPDATED " Tejun Heo
2010-11-30 18:11 ` [PATCH UPDATED#2 " Tejun Heo
2010-11-30 18:22 ` Cyrill Gorcunov
2010-11-30 19:42 ` Tejun Heo
2010-11-30 20:52 ` Cyrill Gorcunov
2010-12-09 9:37 ` Pekka Enberg
2010-12-09 10:47 ` [PATCH UPDATED#3 04/16] x86: setup_local_APIC() must always be called with preemption disabled Tejun Heo
2010-12-09 16:17 ` Cyrill Gorcunov
2010-12-09 16:18 ` Pekka Enberg [this message]
2010-12-09 21:56 ` Thomas Gleixner
2010-12-10 11:09 ` Tejun Heo
2010-12-10 11:10 ` Thomas Gleixner
2010-12-10 12:48 ` [tip:x86/apic-cleanups] x86: apic: Cleanup and simplify setup_local_APIC() tip-bot for Tejun Heo
2010-11-27 15:21 ` [PATCH 05/16] x86: Replace cpu_2_logical_apicid[] with early percpu variable Tejun Heo
2010-11-27 15:21 ` [PATCH 06/16] x86: Always use x86_cpu_to_logical_apicid for cpu -> logical apic id Tejun Heo
2010-11-27 15:21 ` [PATCH 07/16] x86: Remove custom apic->cpu_to_logical_apicid() implementations Tejun Heo
2010-12-09 21:28 ` Thomas Gleixner
2010-12-10 11:12 ` Tejun Heo
2010-12-10 11:18 ` Thomas Gleixner
2010-11-27 15:21 ` [PATCH 08/16] x86: Use apic->cpu_to_logical_apicid() to find out logical apic id mapping early during boot Tejun Heo
2010-11-27 15:21 ` [PATCH 09/16] x86: Implement cpu_to_logical_apicid() for bigsmp_32 Tejun Heo
2010-11-27 15:21 ` [PATCH 10/16] x86: Implement cpu_to_logical_apicid() for summit_32 Tejun Heo
2010-11-27 15:22 ` [PATCH 11/16] x86: Implement cpu_to_logical_apicid() for numaq_32 Tejun Heo
2010-11-27 15:22 ` [PATCH 12/16] x86: Replace apic->apicid_to_node() with ->numa_cpu_node() Tejun Heo
2010-11-27 15:22 ` [PATCH 13/16] x86: Unify cpu/apicid <-> NUMA node mapping between 32 and 64bit Tejun Heo
2010-12-09 21:43 ` Thomas Gleixner
2010-12-10 20:45 ` Tejun Heo
2010-12-10 20:54 ` Tejun Heo
2010-12-10 21:17 ` Yinghai Lu
2010-11-27 15:22 ` [PATCH 14/16] x86: Unify CPU -> " Tejun Heo
2010-12-09 21:49 ` Thomas Gleixner
2010-12-10 11:13 ` Tejun Heo
2010-11-27 15:22 ` [PATCH 15/16] x86: Unify node_to_cpumask_map handling " Tejun Heo
2010-11-27 15:22 ` [PATCH 16/16] x86: Unify NUMA initialization " Tejun Heo
2010-12-07 16:22 ` [PATCHSET] x86: unify x86_32 and 64 NUMA init paths, take#2 Tejun Heo
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