Re: [PATCH] drivers/acpi/processor_driver.c: add missing kfree
From: Srivatsa S. Bhat <hidden>
Date: 2012-03-14 11:38:11
Also in:
linux-acpi, lkml
On 03/10/2012 10:35 PM, Julia Lawall wrote:
From: Julia Lawall <redacted> 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 <redacted> --- 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. Regards, Srivatsa S. Bhat IBM Linux Technology Center
quoted hunk ↗ jump to hunk
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; }