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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2015-08-05 07:52:46 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-08-05 18:46:44 (GMT) |
| commit | 89af7ba5740b5937d10c8de93e79e71e5a933041 (patch) | |
| tree | 0717f4e10938962d7fb57683d1efc8236e9956fd /Documentation/power | |
| parent | 54bf725e5d21022b25fe0d3c103fe82ed13b870b (diff) | |
| download | linux-89af7ba5740b5937d10c8de93e79e71e5a933041.tar.xz | |
cpu-hotplug: convert cpu_hotplug_disabled to a counter
As a prerequisite to exporting cpu_hotplug_enable/cpu_hotplug_disable
functions to modules we need to convert cpu_hotplug_disabled to a counter
to properly support disable -> disable -> enable call sequences. E.g.
after Hyper-V vmbus module (which is supposed to be the first user of
exported cpu_hotplug_enable/cpu_hotplug_disable) did cpu_hotplug_disable()
hibernate path calls disable_nonboot_cpus() and if we hit an error in
_cpu_down() enable_nonboot_cpus() will be called on the failure path (thus
making cpu_hotplug_disabled = 0 and leaving cpu hotplug in 'enabled'
state). Same problem is possible if more than 1 module use
cpu_hotplug_disable/cpu_hotplug_enable on their load/unload paths. When
one of these modules is been unloaded it is logical to leave cpu hotplug
in 'disabled' state.
To support the change we need to increse cpu_hotplug_disabled counter
in disable_nonboot_cpus() unconditionally as all users of
disable_nonboot_cpus() are supposed to do enable_nonboot_cpus() in case
an error was returned.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/power')
| -rw-r--r-- | Documentation/power/suspend-and-cpuhotplug.txt | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/Documentation/power/suspend-and-cpuhotplug.txt b/Documentation/power/suspend-and-cpuhotplug.txt index 2850df3..2fc9095 100644 --- a/Documentation/power/suspend-and-cpuhotplug.txt +++ b/Documentation/power/suspend-and-cpuhotplug.txt @@ -72,7 +72,7 @@ More details follow: | v Disable regular cpu hotplug - by setting cpu_hotplug_disabled=1 + by increasing cpu_hotplug_disabled | v Release cpu_add_remove_lock @@ -89,7 +89,7 @@ Resuming back is likewise, with the counterparts being (in the order of execution during resume): * enable_nonboot_cpus() which involves: | Acquire cpu_add_remove_lock - | Reset cpu_hotplug_disabled to 0, thereby enabling regular cpu hotplug + | Decrease cpu_hotplug_disabled, thereby enabling regular cpu hotplug | Call _cpu_up() [for all those cpus in the frozen_cpus mask, in a loop] | Release cpu_add_remove_lock v @@ -120,7 +120,7 @@ after the entire cycle is complete (i.e., suspend + resume). Acquire cpu_add_remove_lock | v - If cpu_hotplug_disabled is 1 + If cpu_hotplug_disabled > 0 return gracefully | | |