lkml.org 
[lkml]   [2012]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] drivers/acpi/processor_driver.c: add missing kfree
    On 03/10/2012 10:35 PM, Julia Lawall wrote:

    > From: Julia Lawall <julia@diku.dk>
    >
    > 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@diku.dk>
    >
    > ---
    > 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

    > 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;
    > }
    >
    >



    \
     
     \ /
      Last update: 2012-03-14 12:41    [W:0.025 / U:0.040 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site