/* * linux/mm/allocpercpu.c * * Separated from slab.c August 11, 2006 Christoph Lameter */#include <linux/mm.h>#include <linux/module.h>#include <linux/bootmem.h>#include <asm/sections.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, const 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); /* * Generic percpu area setup. */#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREAunsigned long __per_cpu_offset[NR_CPUS] __read_mostly; EXPORT_SYMBOL(__per_cpu_offset); void __init setup_per_cpu_areas(void){	unsigned long size, i;	char *ptr;	unsigned long nr_possible_cpus = num_possible_cpus(); 	/* Copy section for each CPU (we discard the original) */	size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);	ptr = alloc_bootmem_pages(size * nr_possible_cpus); 	for_each_possible_cpu(i) {		__per_cpu_offset[i] = ptr - __per_cpu_start;		memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);		ptr += size;	}}#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */