From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Loaded Hyper-V module will use these functions to disable CPU
hotplug under certain circumstances. Convert cpu_hotplug_disabled
to a counter (protected by cpu_add_remove_lock) to support e.g.
disable -> disable -> enable call sequences.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
Documentation/power/suspend-and-cpuhotplug.txt | 6 +++---
kernel/cpu.c | 13 ++++++++-----
2 files changed, 11 insertions(+), 8 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
|
|
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 94bbe46..8f35ee6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -190,17 +190,19 @@ void cpu_hotplug_done(void)
void cpu_hotplug_disable(void)
{
cpu_maps_update_begin();
- cpu_hotplug_disabled = 1;
+ cpu_hotplug_disabled++;
cpu_maps_update_done();
}
+EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
+ if (cpu_hotplug_disabled)
+ cpu_hotplug_disabled--;
cpu_maps_update_done();
}
-
+EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
#endif /* CONFIG_HOTPLUG_CPU */
/* Need to know about CPUs going up/down? */
@@ -600,7 +602,7 @@ int disable_nonboot_cpus(void)
if (!error) {
BUG_ON(num_online_cpus() > 1);
/* Make sure the CPUs won't be enabled by someone else */
- cpu_hotplug_disabled = 1;
+ cpu_hotplug_disabled++;
} else {
pr_err("Non-boot CPUs are not disabled\n");
}
@@ -622,7 +624,8 @@ void __ref enable_nonboot_cpus(void)
/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
+ if (cpu_hotplug_disabled)
+ cpu_hotplug_disabled--;
if (cpumask_empty(frozen_cpus))
goto out;
--
1.7.4.1
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
