tree 9f4910ad6e95470bb67f504a09b096a4c2822a8d
parent 8848a91068c018bc91f597038a0f41462a0f88a4
author Borislav Petkov <bp@amd64.org> 1282241429 +0200
committer H. Peter Anvin <hpa@linux.intel.com> 1282254463 -0700

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>