/* * 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, 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);