ACPI / processor: Fix STARTING/DYING action in acpi_cpu_soft_notify()

During CPU online/offline testing on a large system, one of the
processors got stuck after the message "bad: scheduling from the
idle thread!".  The problem is that acpi_cpu_soft_notify() calls
acpi_bus_get_device() for all action types.  CPU_STARTING and
CPU_DYING do not allow the notify handlers to sleep.  However,
acpi_bus_get_device() can sleep in acpi_ut_acquire_mutex().

Change acpi_cpu_soft_notify() to return immediately for CPU_STARTING
and CPU_DYING as they have no action in this handler.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 7f70f3182d50..4fcbd670415c 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -121,6 +121,13 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb,
         struct acpi_processor *pr = per_cpu(processors, cpu);
         struct acpi_device *device;
 
+        /*
+         * CPU_STARTING and CPU_DYING must not sleep. Return here since
+         * acpi_bus_get_device() may sleep.
+         */
+        if (action == CPU_STARTING || action == CPU_DYING)
+                return NOTIFY_DONE;
+
         if (!pr || acpi_bus_get_device(pr->handle, &device))
                 return NOTIFY_DONE;