109 lines
2.8 KiB
C
109 lines
2.8 KiB
C
/*
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* mm/percpu-km.c - kernel memory based chunk allocation
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*
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* Copyright (C) 2010 SUSE Linux Products GmbH
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* Copyright (C) 2010 Tejun Heo <tj@kernel.org>
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*
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* This file is released under the GPLv2.
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*
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* Chunks are allocated as a contiguous kernel memory using gfp
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* allocation. This is to be used on nommu architectures.
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*
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* To use percpu-km,
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*
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* - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
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*
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* - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's
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* not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work
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* fine.
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*
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* - NUMA is not supported. When setting up the first chunk,
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* @cpu_distance_fn should be NULL or report all CPUs to be nearer
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* than or at LOCAL_DISTANCE.
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*
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* - It's best if the chunk size is power of two multiple of
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* PAGE_SIZE. Because each chunk is allocated as a contiguous
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* kernel memory block using alloc_pages(), memory will be wasted if
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* chunk size is not aligned. percpu-km code will whine about it.
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*/
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#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
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#error "contiguous percpu allocation is incompatible with paged first chunk"
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#endif
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#include <linux/log2.h>
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static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
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{
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unsigned int cpu;
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for_each_possible_cpu(cpu)
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memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
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return 0;
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}
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static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
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{
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/* nada */
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}
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static struct pcpu_chunk *pcpu_create_chunk(void)
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{
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const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
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struct pcpu_chunk *chunk;
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struct page *pages;
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int i;
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chunk = pcpu_alloc_chunk();
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if (!chunk)
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return NULL;
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pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages));
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if (!pages) {
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pcpu_free_chunk(chunk);
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return NULL;
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}
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for (i = 0; i < nr_pages; i++)
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pcpu_set_page_chunk(nth_page(pages, i), chunk);
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chunk->data = pages;
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chunk->base_addr = page_address(pages) - pcpu_group_offsets[0];
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return chunk;
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}
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static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
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{
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const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
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if (chunk && chunk->data)
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__free_pages(chunk->data, order_base_2(nr_pages));
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pcpu_free_chunk(chunk);
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}
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static struct page *pcpu_addr_to_page(void *addr)
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{
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return virt_to_page(addr);
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}
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static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
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{
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size_t nr_pages, alloc_pages;
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/* all units must be in a single group */
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if (ai->nr_groups != 1) {
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printk(KERN_CRIT "percpu: can't handle more than one groups\n");
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return -EINVAL;
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}
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nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
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alloc_pages = roundup_pow_of_two(nr_pages);
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if (alloc_pages > nr_pages)
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printk(KERN_WARNING "percpu: wasting %zu pages per chunk\n",
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alloc_pages - nr_pages);
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return 0;
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}
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