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Subject[ACPIHP PATCH part4 3/9] ACPIHP/processor: protect accesses to device->driver_data
Date
CPU hotplug notification handler acpi_cpu_soft_notify() and driver
unbind method acpi_processor_remove() may be concurrently called.
acpi_cpu_soft_notify() will access device->driver_data, but that
data structure may be destroyed by acpi_processor_remove().

On the other hand, acpi_cpu_soft_notify() is always called under
protection of get_online_cpus(), so use get_online_cpus() to serialize
all accesses and modifications to device->driver_data.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
drivers/acpi/processor_driver.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 28add34..7d6d794 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -616,6 +616,8 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
return 0;
BUG_ON((pr->id >= nr_cpu_ids) || (pr->id < 0));

+ /* block CPU online/offline operations */
+ get_online_cpus();
result = acpi_processor_link(device, pr);
if (result)
goto err_unlock;
@@ -624,6 +626,7 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
if (result)
goto err_unlink;
}
+ put_online_cpus();

return 0;

@@ -654,8 +657,10 @@ static int acpi_processor_remove(struct acpi_device *device, int type)
return -EINVAL;
}

+ get_online_cpus();
acpi_processor_stop(device, pr);
acpi_processor_unlink(device, pr);
+ put_online_cpus();

free:
device->driver_data = NULL;
--
1.7.9.5


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