/*
   * linux/mm/allocpercpu.c
   *

   * Separated from slab.c August 11, 2006 Christoph Lameter

   */
  #include <linux/mm.h>
  #include <linux/module.h>

  #ifndef cache_line_size
  #define cache_line_size()	L1_CACHE_BYTES
  #endif

  /**
   * percpu_depopulate - depopulate per-cpu data for given cpu
   * @__pdata: per-cpu data to depopulate
   * @cpu: depopulate per-cpu data for this cpu
   *
   * Depopulating per-cpu data for a cpu going offline would be a typical
   * use case. You need to register a cpu hotplug handler for that purpose.
   */

  static void percpu_depopulate(void *__pdata, int cpu)

  {
  	struct percpu_data *pdata = __percpu_disguise(__pdata);

  
  	kfree(pdata->ptrs[cpu]);
  	pdata->ptrs[cpu] = NULL;

  }

  
  /**
   * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
   * @__pdata: per-cpu data to depopulate
   * @mask: depopulate per-cpu data for cpu's selected through mask bits
   */

  static void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)

  {
  	int cpu;

  	for_each_cpu_mask_nr(cpu, *mask)

  		percpu_depopulate(__pdata, cpu);
  }

  
  #define percpu_depopulate_mask(__pdata, mask) \
  	__percpu_depopulate_mask((__pdata), &(mask))

  
  /**
   * percpu_populate - populate per-cpu data for given cpu
   * @__pdata: per-cpu data to populate further
   * @size: size of per-cpu object
   * @gfp: may sleep or not etc.
   * @cpu: populate per-data for this cpu
   *
   * Populating per-cpu data for a cpu coming online would be a typical
   * use case. You need to register a cpu hotplug handler for that purpose.
   * Per-cpu object is populated with zeroed buffer.
   */

  static void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)

  {
  	struct percpu_data *pdata = __percpu_disguise(__pdata);
  	int node = cpu_to_node(cpu);

  	/*
  	 * We should make sure each CPU gets private memory.
  	 */
  	size = roundup(size, cache_line_size());

  	BUG_ON(pdata->ptrs[cpu]);

  	if (node_online(node))
  		pdata->ptrs[cpu] = kmalloc_node(size, gfp|__GFP_ZERO, node);
  	else

  		pdata->ptrs[cpu] = kzalloc(size, gfp);
  	return pdata->ptrs[cpu];
  }

  
  /**
   * percpu_populate_mask - populate per-cpu data for more cpu's
   * @__pdata: per-cpu data to populate further
   * @size: size of per-cpu object
   * @gfp: may sleep or not etc.
   * @mask: populate per-cpu data for cpu's selected through mask bits
   *
   * Per-cpu objects are populated with zeroed buffers.
   */

  static int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
  				  cpumask_t *mask)

  {

  	cpumask_t populated;

  	int cpu;

  	cpus_clear(populated);

  	for_each_cpu_mask_nr(cpu, *mask)

  		if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
  			__percpu_depopulate_mask(__pdata, &populated);
  			return -ENOMEM;
  		} else
  			cpu_set(cpu, populated);
  	return 0;
  }

  
  #define percpu_populate_mask(__pdata, size, gfp, mask) \
  	__percpu_populate_mask((__pdata), (size), (gfp), &(mask))

  
  /**
   * percpu_alloc_mask - initial setup of per-cpu data
   * @size: size of per-cpu object
   * @gfp: may sleep or not etc.
   * @mask: populate per-data for cpu's selected through mask bits
   *
   * Populating per-cpu data for all online cpu's would be a typical use case,
   * which is simplified by the percpu_alloc() wrapper.
   * Per-cpu objects are populated with zeroed buffers.
   */
  void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
  {

  	/*
  	 * We allocate whole cache lines to avoid false sharing
  	 */
  	size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
  	void *pdata = kzalloc(sz, gfp);

  	void *__pdata = __percpu_disguise(pdata);
  
  	if (unlikely(!pdata))
  		return NULL;
  	if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
  		return __pdata;
  	kfree(pdata);
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
  
  /**
   * percpu_free - final cleanup of per-cpu data
   * @__pdata: object to clean up
   *
   * We simply clean up any per-cpu object left. No need for the client to
   * track and specify through a bis mask which per-cpu objects are to free.
   */
  void percpu_free(void *__pdata)
  {

  	if (unlikely(!__pdata))
  		return;

  	__percpu_depopulate_mask(__pdata, &cpu_possible_map);
  	kfree(__percpu_disguise(__pdata));
  }
  EXPORT_SYMBOL_GPL(percpu_free);