On Wed, 14 Mar 2012, Srivatsa S. Bhat wrote:
On 03/10/2012 10:35 PM, Julia Lawall wrote:
From: Julia Lawall <julia@xxxxxxx>
The function acpi_processor_add is stored in the ops.add field of a
acpi_driver structure. This function is then called in
acpi_bus_driver_init. On failure, this function clears the field
device->driver_data, but does not free its contents. Thus the free has to
be done by the add function. In acpi_processor_add, the corresponding
value is pr. This value is currently freed on failure before storing it in
device->driver_data, but not after. This free is added in the error
handling code at the end of the function. The static global variable
"static global variable"?? never heard that one before ;-)
Maybe you meant "per_cpu variable processors"..
processors is also cleared so that it does not refer to a dangling pointer.
processor_device_array is cleared as well.
Signed-off-by: Julia Lawall <julia@xxxxxxx>
---
This is only compile tested. In particular, I don't know if it is correct
to add per_cpu(processor_device_array, pr->id) = NULL;.
No, you shouldn't set it to NULL. processor_device_array was added to check
for buggy BIOSes and return gracefully. Check commit cd8e2b48d (and also the
bugzilla link in that commit).
To have a robust check for buggy BIOSes, we must let it be as it is, even if
it is a stale pointer. That way we can still catch subsequent calls to this
function with the same acpi id (because of a buggy BIOS) and take appropriate
actions.
Other than that, the patch looks good to me.
Thanks for the feedback. Just to be clear, I should keep
+err_clear_processors:
+ per_cpu(processors, pr->id) = NULL;
and just drop:
+ per_cpu(processor_device_array, pr->id) = NULL;
julia
Regards,
Srivatsa S. Bhat
IBM Linux Technology Center
It has nothing to
do with pr, but it looks like stale information in the case of a failure.
drivers/acpi/processor_driver.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 2801b41..9bb0017 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -536,8 +536,8 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
return -ENOMEM;
if (!zalloc_cpumask_var(&pr->throttling.shared_cpu_map, GFP_KERNEL)) {
- kfree(pr);
- return -ENOMEM;
+ result = -ENOMEM;
+ goto err_free_pr;
}
pr->handle = device->handle;
@@ -577,7 +577,7 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
dev = get_cpu_device(pr->id);
if (sysfs_create_link(&device->dev.kobj, &dev->kobj, "sysdev")) {
result = -EFAULT;
- goto err_free_cpumask;
+ goto err_clear_processors;
}
/*
@@ -595,9 +595,13 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
err_remove_sysfs:
sysfs_remove_link(&device->dev.kobj, "sysdev");
+err_clear_processors:
+ per_cpu(processors, pr->id) = NULL;
+ per_cpu(processor_device_array, pr->id) = NULL;
err_free_cpumask:
free_cpumask_var(pr->throttling.shared_cpu_map);
-
+err_free_pr:
+ kfree(pr);
return result;
}
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