From: Borislav Petkov <bp@amd64.org>
Date: Thu, 19 Aug 2010 18:10:29 +0000 (+0200)
Subject: x86, hotplug: Serialize CPU hotplug to avoid bringup concurrency issues
X-Git-Tag: v2.6.36-rc2~11^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d7c53c9e822a4fefa13a0cae76f3190bfd0d5c11;p=pandora-kernel.git

x86, hotplug: Serialize CPU hotplug to avoid bringup concurrency issues

When testing cpu hotplug code on 32-bit we kept hitting the "CPU%d:
Stuck ??" message due to multiple cores concurrently accessing the
cpu_callin_mask, among others.

Since these codepaths are not protected from concurrent access due to
the fact that there's no sane reason for making an already complex
code unnecessarily more complex - we hit the issue only when insanely
switching cores off- and online - serialize hotplugging cores on the
sysfs level and be done with it.

[ v2.1: fix !HOTPLUG_CPU build ]

Cc: <stable@kernel.org>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20100819181029.GC17171@aftab>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---

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