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/*
* 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))
/**
* alloc_percpu - initial setup of per-cpu data
* @size: size of per-cpu object
* @align: alignment
*
* Allocate dynamic percpu area. Percpu objects are populated with
* zeroed buffers.
*/
void *__alloc_percpu(size_t size, size_t align)
{
/*
* 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_KERNEL);
void *__pdata = __percpu_disguise(pdata);
/*
* Can't easily make larger alignment work with kmalloc. WARN
* on it. Larger alignment should only be used for module
* percpu sections on SMP for which this path isn't used.
*/
WARN_ON_ONCE(align > SMP_CACHE_BYTES);
if (unlikely(!pdata))
return NULL;
if (likely(!__percpu_populate_mask(__pdata, size, GFP_KERNEL,
&cpu_possible_map)))
return __pdata;
kfree(pdata);
return NULL;
}
EXPORT_SYMBOL_GPL(__alloc_percpu);
/**
* free_percpu - 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 free_percpu(void *__pdata)
{
if (unlikely(!__pdata))
return;
__percpu_depopulate_mask(__pdata, cpu_possible_mask);
kfree(__percpu_disguise(__pdata));
}
EXPORT_SYMBOL_GPL(free_percpu);
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