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author | Jiri Kosina <jkosina@suse.cz> | 2014-09-03 15:04:28 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-09-17 09:03:59 -0700 |
commit | 4f6a1e6210f5aeed2832d69103fc6511c0ca7c2d (patch) | |
tree | ef8f3feda7804143d3f3870db51734d65568130b /kernel | |
parent | c55d35d2b8fc84218785cf12dd3e895bc83af66d (diff) | |
download | linux-3.10-4f6a1e6210f5aeed2832d69103fc6511c0ca7c2d.tar.gz linux-3.10-4f6a1e6210f5aeed2832d69103fc6511c0ca7c2d.tar.bz2 linux-3.10-4f6a1e6210f5aeed2832d69103fc6511c0ca7c2d.zip |
ACPI / cpuidle: fix deadlock between cpuidle_lock and cpu_hotplug.lock
commit 6726655dfdd2dc60c035c690d9f10cb69d7ea075 upstream.
There is a following AB-BA dependency between cpu_hotplug.lock and
cpuidle_lock:
1) cpu_hotplug.lock -> cpuidle_lock
enable_nonboot_cpus()
_cpu_up()
cpu_hotplug_begin()
LOCK(cpu_hotplug.lock)
cpu_notify()
...
acpi_processor_hotplug()
cpuidle_pause_and_lock()
LOCK(cpuidle_lock)
2) cpuidle_lock -> cpu_hotplug.lock
acpi_os_execute_deferred() workqueue
...
acpi_processor_cst_has_changed()
cpuidle_pause_and_lock()
LOCK(cpuidle_lock)
get_online_cpus()
LOCK(cpu_hotplug.lock)
Fix this by reversing the order acpi_processor_cst_has_changed() does
thigs -- let it first execute the protection against CPU hotplug by
calling get_online_cpus() and obtain the cpuidle lock only after that (and
perform the symmentric change when allowing CPUs hotplug again and
dropping cpuidle lock).
Spotted by lockdep.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions