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-rw-r--r--Documentation/cpu-hotplug.txt9
1 files changed, 7 insertions, 2 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index cc60d29b954c..b6d24c22274b 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -217,14 +217,17 @@ Q: What happens when a CPU is being logically offlined?
A: The following happen, listed in no particular order :-)
- A notification is sent to in-kernel registered modules by sending an event
- CPU_DOWN_PREPARE
+ CPU_DOWN_PREPARE or CPU_DOWN_PREPARE_FROZEN, depending on whether or not the
+ CPU is being offlined while tasks are frozen due to a suspend operation in
+ progress
- All process is migrated away from this outgoing CPU to a new CPU
- All interrupts targeted to this CPU is migrated to a new CPU
- timers/bottom half/task lets are also migrated to a new CPU
- Once all services are migrated, kernel calls an arch specific routine
__cpu_disable() to perform arch specific cleanup.
- Once this is successful, an event for successful cleanup is sent by an event
- CPU_DEAD.
+ CPU_DEAD (or CPU_DEAD_FROZEN if tasks are frozen due to a suspend while the
+ CPU is being offlined).
"It is expected that each service cleans up when the CPU_DOWN_PREPARE
notifier is called, when CPU_DEAD is called its expected there is nothing
@@ -242,9 +245,11 @@ A: This is what you would need in your kernel code to receive notifications.
switch (action) {
case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
foobar_online_action(cpu);
break;
case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
foobar_dead_action(cpu);
break;
}