linux/mm/percpu.c
Tejun Heo 02d51fdfb2 percpu: kill compile warning in pcpu_populate_chunk()
Impact: remove compile warning

Mark local variable map_end in pcpu_populate_chunk() with
uninitialized_var().  The variable is always used in tandem with
map_start and guaranteed to be initialized before use but gcc doesn't
understand that.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
2009-03-01 15:42:36 +09:00

980 lines
27 KiB
C

/*
* linux/mm/percpu.c - percpu memory allocator
*
* Copyright (C) 2009 SUSE Linux Products GmbH
* Copyright (C) 2009 Tejun Heo <tj@kernel.org>
*
* This file is released under the GPLv2.
*
* This is percpu allocator which can handle both static and dynamic
* areas. Percpu areas are allocated in chunks in vmalloc area. Each
* chunk is consisted of num_possible_cpus() units and the first chunk
* is used for static percpu variables in the kernel image (special
* boot time alloc/init handling necessary as these areas need to be
* brought up before allocation services are running). Unit grows as
* necessary and all units grow or shrink in unison. When a chunk is
* filled up, another chunk is allocated. ie. in vmalloc area
*
* c0 c1 c2
* ------------------- ------------------- ------------
* | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
* ------------------- ...... ------------------- .... ------------
*
* Allocation is done in offset-size areas of single unit space. Ie,
* an area of 512 bytes at 6k in c1 occupies 512 bytes at 6k of c1:u0,
* c1:u1, c1:u2 and c1:u3. Percpu access can be done by configuring
* percpu base registers UNIT_SIZE apart.
*
* There are usually many small percpu allocations many of them as
* small as 4 bytes. The allocator organizes chunks into lists
* according to free size and tries to allocate from the fullest one.
* Each chunk keeps the maximum contiguous area size hint which is
* guaranteed to be eqaul to or larger than the maximum contiguous
* area in the chunk. This helps the allocator not to iterate the
* chunk maps unnecessarily.
*
* Allocation state in each chunk is kept using an array of integers
* on chunk->map. A positive value in the map represents a free
* region and negative allocated. Allocation inside a chunk is done
* by scanning this map sequentially and serving the first matching
* entry. This is mostly copied from the percpu_modalloc() allocator.
* Chunks are also linked into a rb tree to ease address to chunk
* mapping during free.
*
* To use this allocator, arch code should do the followings.
*
* - define CONFIG_HAVE_DYNAMIC_PER_CPU_AREA
*
* - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
* regular address to percpu pointer and back
*
* - use pcpu_setup_first_chunk() during percpu area initialization to
* setup the first chunk containing the kernel static percpu area
*/
#include <linux/bitmap.h>
#include <linux/bootmem.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/pfn.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */
#define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */
struct pcpu_chunk {
struct list_head list; /* linked to pcpu_slot lists */
struct rb_node rb_node; /* key is chunk->vm->addr */
int free_size; /* free bytes in the chunk */
int contig_hint; /* max contiguous size hint */
struct vm_struct *vm; /* mapped vmalloc region */
int map_used; /* # of map entries used */
int map_alloc; /* # of map entries allocated */
int *map; /* allocation map */
bool immutable; /* no [de]population allowed */
struct page *page[]; /* #cpus * UNIT_PAGES */
};
static int pcpu_unit_pages __read_mostly;
static int pcpu_unit_size __read_mostly;
static int pcpu_chunk_size __read_mostly;
static int pcpu_nr_slots __read_mostly;
static size_t pcpu_chunk_struct_size __read_mostly;
/* the address of the first chunk which starts with the kernel static area */
void *pcpu_base_addr __read_mostly;
EXPORT_SYMBOL_GPL(pcpu_base_addr);
/* the size of kernel static area */
static int pcpu_static_size __read_mostly;
/*
* One mutex to rule them all.
*
* The following mutex is grabbed in the outermost public alloc/free
* interface functions and released only when the operation is
* complete. As such, every function in this file other than the
* outermost functions are called under pcpu_mutex.
*
* It can easily be switched to use spinlock such that only the area
* allocation and page population commit are protected with it doing
* actual [de]allocation without holding any lock. However, given
* what this allocator does, I think it's better to let them run
* sequentially.
*/
static DEFINE_MUTEX(pcpu_mutex);
static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */
static struct rb_root pcpu_addr_root = RB_ROOT; /* chunks by address */
static int __pcpu_size_to_slot(int size)
{
int highbit = fls(size); /* size is in bytes */
return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
}
static int pcpu_size_to_slot(int size)
{
if (size == pcpu_unit_size)
return pcpu_nr_slots - 1;
return __pcpu_size_to_slot(size);
}
static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
{
if (chunk->free_size < sizeof(int) || chunk->contig_hint < sizeof(int))
return 0;
return pcpu_size_to_slot(chunk->free_size);
}
static int pcpu_page_idx(unsigned int cpu, int page_idx)
{
return cpu * pcpu_unit_pages + page_idx;
}
static struct page **pcpu_chunk_pagep(struct pcpu_chunk *chunk,
unsigned int cpu, int page_idx)
{
return &chunk->page[pcpu_page_idx(cpu, page_idx)];
}
static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
unsigned int cpu, int page_idx)
{
return (unsigned long)chunk->vm->addr +
(pcpu_page_idx(cpu, page_idx) << PAGE_SHIFT);
}
static bool pcpu_chunk_page_occupied(struct pcpu_chunk *chunk,
int page_idx)
{
return *pcpu_chunk_pagep(chunk, 0, page_idx) != NULL;
}
/**
* pcpu_realloc - versatile realloc
* @p: the current pointer (can be NULL for new allocations)
* @size: the current size in bytes (can be 0 for new allocations)
* @new_size: the wanted new size in bytes (can be 0 for free)
*
* More robust realloc which can be used to allocate, resize or free a
* memory area of arbitrary size. If the needed size goes over
* PAGE_SIZE, kernel VM is used.
*
* RETURNS:
* The new pointer on success, NULL on failure.
*/
static void *pcpu_realloc(void *p, size_t size, size_t new_size)
{
void *new;
if (new_size <= PAGE_SIZE)
new = kmalloc(new_size, GFP_KERNEL);
else
new = vmalloc(new_size);
if (new_size && !new)
return NULL;
memcpy(new, p, min(size, new_size));
if (new_size > size)
memset(new + size, 0, new_size - size);
if (size <= PAGE_SIZE)
kfree(p);
else
vfree(p);
return new;
}
/**
* pcpu_chunk_relocate - put chunk in the appropriate chunk slot
* @chunk: chunk of interest
* @oslot: the previous slot it was on
*
* This function is called after an allocation or free changed @chunk.
* New slot according to the changed state is determined and @chunk is
* moved to the slot.
*/
static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
{
int nslot = pcpu_chunk_slot(chunk);
if (oslot != nslot) {
if (oslot < nslot)
list_move(&chunk->list, &pcpu_slot[nslot]);
else
list_move_tail(&chunk->list, &pcpu_slot[nslot]);
}
}
static struct rb_node **pcpu_chunk_rb_search(void *addr,
struct rb_node **parentp)
{
struct rb_node **p = &pcpu_addr_root.rb_node;
struct rb_node *parent = NULL;
struct pcpu_chunk *chunk;
while (*p) {
parent = *p;
chunk = rb_entry(parent, struct pcpu_chunk, rb_node);
if (addr < chunk->vm->addr)
p = &(*p)->rb_left;
else if (addr > chunk->vm->addr)
p = &(*p)->rb_right;
else
break;
}
if (parentp)
*parentp = parent;
return p;
}
/**
* pcpu_chunk_addr_search - search for chunk containing specified address
* @addr: address to search for
*
* Look for chunk which might contain @addr. More specifically, it
* searchs for the chunk with the highest start address which isn't
* beyond @addr.
*
* RETURNS:
* The address of the found chunk.
*/
static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
{
struct rb_node *n, *parent;
struct pcpu_chunk *chunk;
n = *pcpu_chunk_rb_search(addr, &parent);
if (!n) {
/* no exactly matching chunk, the parent is the closest */
n = parent;
BUG_ON(!n);
}
chunk = rb_entry(n, struct pcpu_chunk, rb_node);
if (addr < chunk->vm->addr) {
/* the parent was the next one, look for the previous one */
n = rb_prev(n);
BUG_ON(!n);
chunk = rb_entry(n, struct pcpu_chunk, rb_node);
}
return chunk;
}
/**
* pcpu_chunk_addr_insert - insert chunk into address rb tree
* @new: chunk to insert
*
* Insert @new into address rb tree.
*/
static void pcpu_chunk_addr_insert(struct pcpu_chunk *new)
{
struct rb_node **p, *parent;
p = pcpu_chunk_rb_search(new->vm->addr, &parent);
BUG_ON(*p);
rb_link_node(&new->rb_node, parent, p);
rb_insert_color(&new->rb_node, &pcpu_addr_root);
}
/**
* pcpu_split_block - split a map block
* @chunk: chunk of interest
* @i: index of map block to split
* @head: head size in bytes (can be 0)
* @tail: tail size in bytes (can be 0)
*
* Split the @i'th map block into two or three blocks. If @head is
* non-zero, @head bytes block is inserted before block @i moving it
* to @i+1 and reducing its size by @head bytes.
*
* If @tail is non-zero, the target block, which can be @i or @i+1
* depending on @head, is reduced by @tail bytes and @tail byte block
* is inserted after the target block.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
static int pcpu_split_block(struct pcpu_chunk *chunk, int i, int head, int tail)
{
int nr_extra = !!head + !!tail;
int target = chunk->map_used + nr_extra;
/* reallocation required? */
if (chunk->map_alloc < target) {
int new_alloc = chunk->map_alloc;
int *new;
while (new_alloc < target)
new_alloc *= 2;
new = pcpu_realloc(chunk->map,
chunk->map_alloc * sizeof(new[0]),
new_alloc * sizeof(new[0]));
if (!new)
return -ENOMEM;
chunk->map_alloc = new_alloc;
chunk->map = new;
}
/* insert a new subblock */
memmove(&chunk->map[i + nr_extra], &chunk->map[i],
sizeof(chunk->map[0]) * (chunk->map_used - i));
chunk->map_used += nr_extra;
if (head) {
chunk->map[i + 1] = chunk->map[i] - head;
chunk->map[i++] = head;
}
if (tail) {
chunk->map[i++] -= tail;
chunk->map[i] = tail;
}
return 0;
}
/**
* pcpu_alloc_area - allocate area from a pcpu_chunk
* @chunk: chunk of interest
* @size: wanted size in bytes
* @align: wanted align
*
* Try to allocate @size bytes area aligned at @align from @chunk.
* Note that this function only allocates the offset. It doesn't
* populate or map the area.
*
* RETURNS:
* Allocated offset in @chunk on success, -errno on failure.
*/
static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
{
int oslot = pcpu_chunk_slot(chunk);
int max_contig = 0;
int i, off;
/*
* The static chunk initially doesn't have map attached
* because kmalloc wasn't available during init. Give it one.
*/
if (unlikely(!chunk->map)) {
chunk->map = pcpu_realloc(NULL, 0,
PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
if (!chunk->map)
return -ENOMEM;
chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
chunk->map[chunk->map_used++] = -pcpu_static_size;
if (chunk->free_size)
chunk->map[chunk->map_used++] = chunk->free_size;
}
for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) {
bool is_last = i + 1 == chunk->map_used;
int head, tail;
/* extra for alignment requirement */
head = ALIGN(off, align) - off;
BUG_ON(i == 0 && head != 0);
if (chunk->map[i] < 0)
continue;
if (chunk->map[i] < head + size) {
max_contig = max(chunk->map[i], max_contig);
continue;
}
/*
* If head is small or the previous block is free,
* merge'em. Note that 'small' is defined as smaller
* than sizeof(int), which is very small but isn't too
* uncommon for percpu allocations.
*/
if (head && (head < sizeof(int) || chunk->map[i - 1] > 0)) {
if (chunk->map[i - 1] > 0)
chunk->map[i - 1] += head;
else {
chunk->map[i - 1] -= head;
chunk->free_size -= head;
}
chunk->map[i] -= head;
off += head;
head = 0;
}
/* if tail is small, just keep it around */
tail = chunk->map[i] - head - size;
if (tail < sizeof(int))
tail = 0;
/* split if warranted */
if (head || tail) {
if (pcpu_split_block(chunk, i, head, tail))
return -ENOMEM;
if (head) {
i++;
off += head;
max_contig = max(chunk->map[i - 1], max_contig);
}
if (tail)
max_contig = max(chunk->map[i + 1], max_contig);
}
/* update hint and mark allocated */
if (is_last)
chunk->contig_hint = max_contig; /* fully scanned */
else
chunk->contig_hint = max(chunk->contig_hint,
max_contig);
chunk->free_size -= chunk->map[i];
chunk->map[i] = -chunk->map[i];
pcpu_chunk_relocate(chunk, oslot);
return off;
}
chunk->contig_hint = max_contig; /* fully scanned */
pcpu_chunk_relocate(chunk, oslot);
/*
* Tell the upper layer that this chunk has no area left.
* Note that this is not an error condition but a notification
* to upper layer that it needs to look at other chunks.
* -ENOSPC is chosen as it isn't used in memory subsystem and
* matches the meaning in a way.
*/
return -ENOSPC;
}
/**
* pcpu_free_area - free area to a pcpu_chunk
* @chunk: chunk of interest
* @freeme: offset of area to free
*
* Free area starting from @freeme to @chunk. Note that this function
* only modifies the allocation map. It doesn't depopulate or unmap
* the area.
*/
static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme)
{
int oslot = pcpu_chunk_slot(chunk);
int i, off;
for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++]))
if (off == freeme)
break;
BUG_ON(off != freeme);
BUG_ON(chunk->map[i] > 0);
chunk->map[i] = -chunk->map[i];
chunk->free_size += chunk->map[i];
/* merge with previous? */
if (i > 0 && chunk->map[i - 1] >= 0) {
chunk->map[i - 1] += chunk->map[i];
chunk->map_used--;
memmove(&chunk->map[i], &chunk->map[i + 1],
(chunk->map_used - i) * sizeof(chunk->map[0]));
i--;
}
/* merge with next? */
if (i + 1 < chunk->map_used && chunk->map[i + 1] >= 0) {
chunk->map[i] += chunk->map[i + 1];
chunk->map_used--;
memmove(&chunk->map[i + 1], &chunk->map[i + 2],
(chunk->map_used - (i + 1)) * sizeof(chunk->map[0]));
}
chunk->contig_hint = max(chunk->map[i], chunk->contig_hint);
pcpu_chunk_relocate(chunk, oslot);
}
/**
* pcpu_unmap - unmap pages out of a pcpu_chunk
* @chunk: chunk of interest
* @page_start: page index of the first page to unmap
* @page_end: page index of the last page to unmap + 1
* @flush: whether to flush cache and tlb or not
*
* For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
* If @flush is true, vcache is flushed before unmapping and tlb
* after.
*/
static void pcpu_unmap(struct pcpu_chunk *chunk, int page_start, int page_end,
bool flush)
{
unsigned int last = num_possible_cpus() - 1;
unsigned int cpu;
/* unmap must not be done on immutable chunk */
WARN_ON(chunk->immutable);
/*
* Each flushing trial can be very expensive, issue flush on
* the whole region at once rather than doing it for each cpu.
* This could be an overkill but is more scalable.
*/
if (flush)
flush_cache_vunmap(pcpu_chunk_addr(chunk, 0, page_start),
pcpu_chunk_addr(chunk, last, page_end));
for_each_possible_cpu(cpu)
unmap_kernel_range_noflush(
pcpu_chunk_addr(chunk, cpu, page_start),
(page_end - page_start) << PAGE_SHIFT);
/* ditto as flush_cache_vunmap() */
if (flush)
flush_tlb_kernel_range(pcpu_chunk_addr(chunk, 0, page_start),
pcpu_chunk_addr(chunk, last, page_end));
}
/**
* pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
* @chunk: chunk to depopulate
* @off: offset to the area to depopulate
* @size: size of the area to depopulate in bytes
* @flush: whether to flush cache and tlb or not
*
* For each cpu, depopulate and unmap pages [@page_start,@page_end)
* from @chunk. If @flush is true, vcache is flushed before unmapping
* and tlb after.
*/
static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size,
bool flush)
{
int page_start = PFN_DOWN(off);
int page_end = PFN_UP(off + size);
int unmap_start = -1;
int uninitialized_var(unmap_end);
unsigned int cpu;
int i;
for (i = page_start; i < page_end; i++) {
for_each_possible_cpu(cpu) {
struct page **pagep = pcpu_chunk_pagep(chunk, cpu, i);
if (!*pagep)
continue;
__free_page(*pagep);
/*
* If it's partial depopulation, it might get
* populated or depopulated again. Mark the
* page gone.
*/
*pagep = NULL;
unmap_start = unmap_start < 0 ? i : unmap_start;
unmap_end = i + 1;
}
}
if (unmap_start >= 0)
pcpu_unmap(chunk, unmap_start, unmap_end, flush);
}
/**
* pcpu_map - map pages into a pcpu_chunk
* @chunk: chunk of interest
* @page_start: page index of the first page to map
* @page_end: page index of the last page to map + 1
*
* For each cpu, map pages [@page_start,@page_end) into @chunk.
* vcache is flushed afterwards.
*/
static int pcpu_map(struct pcpu_chunk *chunk, int page_start, int page_end)
{
unsigned int last = num_possible_cpus() - 1;
unsigned int cpu;
int err;
/* map must not be done on immutable chunk */
WARN_ON(chunk->immutable);
for_each_possible_cpu(cpu) {
err = map_kernel_range_noflush(
pcpu_chunk_addr(chunk, cpu, page_start),
(page_end - page_start) << PAGE_SHIFT,
PAGE_KERNEL,
pcpu_chunk_pagep(chunk, cpu, page_start));
if (err < 0)
return err;
}
/* flush at once, please read comments in pcpu_unmap() */
flush_cache_vmap(pcpu_chunk_addr(chunk, 0, page_start),
pcpu_chunk_addr(chunk, last, page_end));
return 0;
}
/**
* pcpu_populate_chunk - populate and map an area of a pcpu_chunk
* @chunk: chunk of interest
* @off: offset to the area to populate
* @size: size of the area to populate in bytes
*
* For each cpu, populate and map pages [@page_start,@page_end) into
* @chunk. The area is cleared on return.
*/
static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
{
const gfp_t alloc_mask = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
int page_start = PFN_DOWN(off);
int page_end = PFN_UP(off + size);
int map_start = -1;
int uninitialized_var(map_end);
unsigned int cpu;
int i;
for (i = page_start; i < page_end; i++) {
if (pcpu_chunk_page_occupied(chunk, i)) {
if (map_start >= 0) {
if (pcpu_map(chunk, map_start, map_end))
goto err;
map_start = -1;
}
continue;
}
map_start = map_start < 0 ? i : map_start;
map_end = i + 1;
for_each_possible_cpu(cpu) {
struct page **pagep = pcpu_chunk_pagep(chunk, cpu, i);
*pagep = alloc_pages_node(cpu_to_node(cpu),
alloc_mask, 0);
if (!*pagep)
goto err;
}
}
if (map_start >= 0 && pcpu_map(chunk, map_start, map_end))
goto err;
for_each_possible_cpu(cpu)
memset(chunk->vm->addr + cpu * pcpu_unit_size + off, 0,
size);
return 0;
err:
/* likely under heavy memory pressure, give memory back */
pcpu_depopulate_chunk(chunk, off, size, true);
return -ENOMEM;
}
static void free_pcpu_chunk(struct pcpu_chunk *chunk)
{
if (!chunk)
return;
if (chunk->vm)
free_vm_area(chunk->vm);
pcpu_realloc(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]), 0);
kfree(chunk);
}
static struct pcpu_chunk *alloc_pcpu_chunk(void)
{
struct pcpu_chunk *chunk;
chunk = kzalloc(pcpu_chunk_struct_size, GFP_KERNEL);
if (!chunk)
return NULL;
chunk->map = pcpu_realloc(NULL, 0,
PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
chunk->map[chunk->map_used++] = pcpu_unit_size;
chunk->vm = get_vm_area(pcpu_chunk_size, GFP_KERNEL);
if (!chunk->vm) {
free_pcpu_chunk(chunk);
return NULL;
}
INIT_LIST_HEAD(&chunk->list);
chunk->free_size = pcpu_unit_size;
chunk->contig_hint = pcpu_unit_size;
return chunk;
}
/**
* __alloc_percpu - allocate percpu area
* @size: size of area to allocate in bytes
* @align: alignment of area (max PAGE_SIZE)
*
* Allocate percpu area of @size bytes aligned at @align. Might
* sleep. Might trigger writeouts.
*
* RETURNS:
* Percpu pointer to the allocated area on success, NULL on failure.
*/
void *__alloc_percpu(size_t size, size_t align)
{
void *ptr = NULL;
struct pcpu_chunk *chunk;
int slot, off;
if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
WARN(true, "illegal size (%zu) or align (%zu) for "
"percpu allocation\n", size, align);
return NULL;
}
mutex_lock(&pcpu_mutex);
/* allocate area */
for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
list_for_each_entry(chunk, &pcpu_slot[slot], list) {
if (size > chunk->contig_hint)
continue;
off = pcpu_alloc_area(chunk, size, align);
if (off >= 0)
goto area_found;
if (off != -ENOSPC)
goto out_unlock;
}
}
/* hmmm... no space left, create a new chunk */
chunk = alloc_pcpu_chunk();
if (!chunk)
goto out_unlock;
pcpu_chunk_relocate(chunk, -1);
pcpu_chunk_addr_insert(chunk);
off = pcpu_alloc_area(chunk, size, align);
if (off < 0)
goto out_unlock;
area_found:
/* populate, map and clear the area */
if (pcpu_populate_chunk(chunk, off, size)) {
pcpu_free_area(chunk, off);
goto out_unlock;
}
ptr = __addr_to_pcpu_ptr(chunk->vm->addr + off);
out_unlock:
mutex_unlock(&pcpu_mutex);
return ptr;
}
EXPORT_SYMBOL_GPL(__alloc_percpu);
static void pcpu_kill_chunk(struct pcpu_chunk *chunk)
{
WARN_ON(chunk->immutable);
pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size, false);
list_del(&chunk->list);
rb_erase(&chunk->rb_node, &pcpu_addr_root);
free_pcpu_chunk(chunk);
}
/**
* free_percpu - free percpu area
* @ptr: pointer to area to free
*
* Free percpu area @ptr. Might sleep.
*/
void free_percpu(void *ptr)
{
void *addr = __pcpu_ptr_to_addr(ptr);
struct pcpu_chunk *chunk;
int off;
if (!ptr)
return;
mutex_lock(&pcpu_mutex);
chunk = pcpu_chunk_addr_search(addr);
off = addr - chunk->vm->addr;
pcpu_free_area(chunk, off);
/* the chunk became fully free, kill one if there are other free ones */
if (chunk->free_size == pcpu_unit_size) {
struct pcpu_chunk *pos;
list_for_each_entry(pos,
&pcpu_slot[pcpu_chunk_slot(chunk)], list)
if (pos != chunk) {
pcpu_kill_chunk(pos);
break;
}
}
mutex_unlock(&pcpu_mutex);
}
EXPORT_SYMBOL_GPL(free_percpu);
/**
* pcpu_setup_first_chunk - initialize the first percpu chunk
* @get_page_fn: callback to fetch page pointer
* @static_size: the size of static percpu area in bytes
* @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, 0 for auto
* @free_size: free size in bytes, 0 for auto
* @base_addr: mapped address, NULL for auto
* @populate_pte_fn: callback to allocate pagetable, NULL if unnecessary
*
* Initialize the first percpu chunk which contains the kernel static
* perpcu area. This function is to be called from arch percpu area
* setup path. The first two parameters are mandatory. The rest are
* optional.
*
* @get_page_fn() should return pointer to percpu page given cpu
* number and page number. It should at least return enough pages to
* cover the static area. The returned pages for static area should
* have been initialized with valid data. If @unit_size is specified,
* it can also return pages after the static area. NULL return
* indicates end of pages for the cpu. Note that @get_page_fn() must
* return the same number of pages for all cpus.
*
* @unit_size, if non-zero, determines unit size and must be aligned
* to PAGE_SIZE and equal to or larger than @static_size + @free_size.
*
* @free_size determines the number of free bytes after the static
* area in the first chunk. If zero, whatever left is available.
* Specifying non-zero value make percpu leave the area after
* @static_size + @free_size alone.
*
* Non-null @base_addr means that the caller already allocated virtual
* region for the first chunk and mapped it. percpu must not mess
* with the chunk. Note that @base_addr with 0 @unit_size or non-NULL
* @populate_pte_fn doesn't make any sense.
*
* @populate_pte_fn is used to populate the pagetable. NULL means the
* caller already populated the pagetable.
*
* RETURNS:
* The determined pcpu_unit_size which can be used to initialize
* percpu access.
*/
size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
size_t static_size, size_t unit_size,
size_t free_size, void *base_addr,
pcpu_populate_pte_fn_t populate_pte_fn)
{
static struct vm_struct static_vm;
struct pcpu_chunk *static_chunk;
unsigned int cpu;
int nr_pages;
int err, i;
/* santiy checks */
BUG_ON(!static_size);
BUG_ON(!unit_size && free_size);
BUG_ON(unit_size && unit_size < static_size + free_size);
BUG_ON(unit_size & ~PAGE_MASK);
BUG_ON(base_addr && !unit_size);
BUG_ON(base_addr && populate_pte_fn);
if (unit_size)
pcpu_unit_pages = unit_size >> PAGE_SHIFT;
else
pcpu_unit_pages = max_t(int, PCPU_MIN_UNIT_SIZE >> PAGE_SHIFT,
PFN_UP(static_size));
pcpu_static_size = static_size;
pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
pcpu_chunk_size = num_possible_cpus() * pcpu_unit_size;
pcpu_chunk_struct_size = sizeof(struct pcpu_chunk)
+ num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *);
/*
* Allocate chunk slots. The additional last slot is for
* empty chunks.
*/
pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
pcpu_slot = alloc_bootmem(pcpu_nr_slots * sizeof(pcpu_slot[0]));
for (i = 0; i < pcpu_nr_slots; i++)
INIT_LIST_HEAD(&pcpu_slot[i]);
/* init static_chunk */
static_chunk = alloc_bootmem(pcpu_chunk_struct_size);
INIT_LIST_HEAD(&static_chunk->list);
static_chunk->vm = &static_vm;
if (free_size)
static_chunk->free_size = free_size;
else
static_chunk->free_size = pcpu_unit_size - pcpu_static_size;
static_chunk->contig_hint = static_chunk->free_size;
/* allocate vm address */
static_vm.flags = VM_ALLOC;
static_vm.size = pcpu_chunk_size;
if (!base_addr)
vm_area_register_early(&static_vm, PAGE_SIZE);
else {
/*
* Pages already mapped. No need to remap into
* vmalloc area. In this case the static chunk can't
* be mapped or unmapped by percpu and is marked
* immutable.
*/
static_vm.addr = base_addr;
static_chunk->immutable = true;
}
/* assign pages */
nr_pages = -1;
for_each_possible_cpu(cpu) {
for (i = 0; i < pcpu_unit_pages; i++) {
struct page *page = get_page_fn(cpu, i);
if (!page)
break;
*pcpu_chunk_pagep(static_chunk, cpu, i) = page;
}
BUG_ON(i < PFN_UP(pcpu_static_size));
if (nr_pages < 0)
nr_pages = i;
else
BUG_ON(nr_pages != i);
}
/* map them */
if (populate_pte_fn) {
for_each_possible_cpu(cpu)
for (i = 0; i < nr_pages; i++)
populate_pte_fn(pcpu_chunk_addr(static_chunk,
cpu, i));
err = pcpu_map(static_chunk, 0, nr_pages);
if (err)
panic("failed to setup static percpu area, err=%d\n",
err);
}
/* link static_chunk in */
pcpu_chunk_relocate(static_chunk, -1);
pcpu_chunk_addr_insert(static_chunk);
/* we're done */
pcpu_base_addr = (void *)pcpu_chunk_addr(static_chunk, 0, 0);
return pcpu_unit_size;
}