Re: [Xen-devel] [PATCH linux-2.6.18/ACPI: eliminate restriction on ACPI processor ID range

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 06/12/2011 13:17, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> Rather than storing the reference acpi_device pointers in an ACPI-ID-
> indexed array (and having a bogus BUG_ON() check on a platform provided
> value), use a radix tree instead.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Keir Fraser <keir@xxxxxxx>

> --- a/drivers/acpi/processor_core.c
> +++ b/drivers/acpi/processor_core.c
> @@ -513,7 +513,14 @@ static int acpi_processor_get_info(struc
> return 0;
>  }
>  
> -static void *processor_device_array[NR_ACPI_CPUS];
> +#ifndef CONFIG_XEN
> +static void *processor_device_array[NR_CPUS];
> +#else
> +#include <linux/mutex.h>
> +#include <linux/radix-tree.h>
> +static DEFINE_MUTEX(processor_device_mutex);
> +static RADIX_TREE(processor_device_tree, GFP_KERNEL);
> +#endif
>  
>  static int acpi_processor_start(struct acpi_device *device)
>  {
> @@ -541,9 +548,20 @@ static int __cpuinit acpi_processor_add(
> * Don't trust it blindly
> */
>  #ifdef CONFIG_XEN
> - BUG_ON(pr->acpi_id >= NR_ACPI_CPUS);
> - if (processor_device_array[pr->acpi_id] != NULL &&
> -     processor_device_array[pr->acpi_id] != (void *)device) {
> + mutex_lock(&processor_device_mutex);
> + result = radix_tree_insert(&processor_device_tree,
> +       pr->acpi_id, device);
> + switch (result) {
> + default:
> +  goto end_unlock;
> + case -EEXIST:
> +  if (radix_tree_lookup(&processor_device_tree,
> +          pr->acpi_id) == device) {
> + case 0:
> +   mutex_unlock(&processor_device_mutex);
> +   break;
> +  }
> +  mutex_unlock(&processor_device_mutex);
>  #else
> if (processor_device_array[pr->id] != NULL &&
>    processor_device_array[pr->id] != (void *)device) {
> @@ -553,14 +571,11 @@ static int __cpuinit acpi_processor_add(
> return -ENODEV;
> }
>  #ifdef CONFIG_XEN
> - processor_device_array[pr->acpi_id] = (void *)device;
> if (pr->id != -1)
> -  processors[pr->id] = pr;
>  #else
> processor_device_array[pr->id] = (void *)device;
> -
> - processors[pr->id] = pr;
>  #endif /* CONFIG_XEN */
> + processors[pr->id] = pr;
>  
> result = acpi_processor_add_fs(device);
> if (result)
> @@ -602,6 +617,14 @@ err_thermal_unregister:
> }
>  
>        end:
> +#ifdef CONFIG_XEN
> + mutex_lock(&processor_device_mutex);
> + if (radix_tree_lookup(&processor_device_tree,
> +         pr->acpi_id) == device)
> +  radix_tree_delete(&processor_device_tree, pr->acpi_id);
> +      end_unlock:
> + mutex_unlock(&processor_device_mutex);
> +#endif
>  
> return result;
>  }
> @@ -692,10 +715,8 @@ static int acpi_processor_remove(struct
>  
>  #ifdef CONFIG_XEN
> if (pr->id != -1)
> -  processors[pr->id] = NULL;
> -#else
> +#endif
> processors[pr->id] = NULL;
> -#endif /* CONFIG_XEN */
>  
>  
> kfree(pr);
> @@ -992,6 +1013,30 @@ static void __exit acpi_processor_exit(v
>  
> remove_proc_entry(ACPI_PROCESSOR_CLASS, acpi_root_dir);
>  
> +#ifdef CONFIG_XEN
> + {
> +  struct acpi_device *dev;
> +  unsigned int idx = 0;
> +
> +  while (radix_tree_gang_lookup(&processor_device_tree,
> +           (void **)&dev, idx, 1)) {
> +   struct acpi_processor *pr = acpi_driver_data(dev);
> +
> +   /* prevent live lock */
> +   if (pr->acpi_id < idx) {
> +    printk(KERN_WARNING PREFIX "ID %u unexpected"
> +           " (less than %u); leaking memory\n",
> +           pr->acpi_id, idx);
> +    break;
> +   }
> +   idx = pr->acpi_id;
> +   radix_tree_delete(&processor_device_tree, idx);
> +   if (!++idx)
> +    break;
> +  }
> + }
> +#endif
> +
> return;
>  }
>  
> --- a/include/acpi/processor.h
> +++ b/include/acpi/processor.h
> @@ -24,12 +24,6 @@
>  #define ACPI_TSD_REV0_REVISION  0 /* Support for _PSD as in ACPI 3.0 */
>  #define ACPI_TSD_REV0_ENTRIES  5
>  
> -#ifdef CONFIG_XEN
> -#define NR_ACPI_CPUS   (NR_CPUS < 256 ? 256 : NR_CPUS)
> -#else
> -#define NR_ACPI_CPUS   NR_CPUS
> -#endif /* CONFIG_XEN */
> -
>  /*
>   * Types of coordination defined in ACPI 3.0. Same macros can be used across
>   * P, C and T states
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel