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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

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* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability
This commit is contained in:
Linus Torvalds 2009-11-14 12:59:06 -08:00
commit e0a2af1e60
1 changed files with 81 additions and 40 deletions
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121
mm/percpu.c
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@ -355,62 +355,86 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
}
/**
* pcpu_extend_area_map - extend area map for allocation
* @chunk: target chunk
* pcpu_need_to_extend - determine whether chunk area map needs to be extended
* @chunk: chunk of interest
*
* Extend area map of @chunk so that it can accomodate an allocation.
* A single allocation can split an area into three areas, so this
* function makes sure that @chunk->map has at least two extra slots.
* Determine whether area map of @chunk needs to be extended to
* accomodate a new allocation.
*
* CONTEXT:
* pcpu_alloc_mutex, pcpu_lock. pcpu_lock is released and reacquired
* if area map is extended.
* pcpu_lock.
*
* RETURNS:
* 0 if noop, 1 if successfully extended, -errno on failure.
* New target map allocation length if extension is necessary, 0
* otherwise.
*/
static int pcpu_extend_area_map(struct pcpu_chunk *chunk, unsigned long *flags)
static int pcpu_need_to_extend(struct pcpu_chunk *chunk)
{
int new_alloc;
int *new;
size_t size;
/* has enough? */
if (chunk->map_alloc >= chunk->map_used + 2)
return 0;
spin_unlock_irqrestore(&pcpu_lock, *flags);
new_alloc = PCPU_DFL_MAP_ALLOC;
while (new_alloc < chunk->map_used + 2)
new_alloc *= 2;
new = pcpu_mem_alloc(new_alloc * sizeof(new[0]));
if (!new) {
spin_lock_irqsave(&pcpu_lock, *flags);
return new_alloc;
}
/**
* pcpu_extend_area_map - extend area map of a chunk
* @chunk: chunk of interest
* @new_alloc: new target allocation length of the area map
*
* Extend area map of @chunk to have @new_alloc entries.
*
* CONTEXT:
* Does GFP_KERNEL allocation. Grabs and releases pcpu_lock.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
{
int *old = NULL, *new = NULL;
size_t old_size = 0, new_size = new_alloc * sizeof(new[0]);
unsigned long flags;
new = pcpu_mem_alloc(new_size);
if (!new)
return -ENOMEM;
}
/*
* Acquire pcpu_lock and switch to new area map. Only free
* could have happened inbetween, so map_used couldn't have
* grown.
*/
spin_lock_irqsave(&pcpu_lock, *flags);
BUG_ON(new_alloc < chunk->map_used + 2);
/* acquire pcpu_lock and switch to new area map */
spin_lock_irqsave(&pcpu_lock, flags);
size = chunk->map_alloc * sizeof(chunk->map[0]);
memcpy(new, chunk->map, size);
if (new_alloc <= chunk->map_alloc)
goto out_unlock;
old_size = chunk->map_alloc * sizeof(chunk->map[0]);
memcpy(new, chunk->map, old_size);
/*
* map_alloc < PCPU_DFL_MAP_ALLOC indicates that the chunk is
* one of the first chunks and still using static map.
*/
if (chunk->map_alloc >= PCPU_DFL_MAP_ALLOC)
pcpu_mem_free(chunk->map, size);
old = chunk->map;
chunk->map_alloc = new_alloc;
chunk->map = new;
new = NULL;
out_unlock:
spin_unlock_irqrestore(&pcpu_lock, flags);
/*
* pcpu_mem_free() might end up calling vfree() which uses
* IRQ-unsafe lock and thus can't be called under pcpu_lock.
*/
pcpu_mem_free(old, old_size);
pcpu_mem_free(new, new_size);
return 0;
}
@ -1049,7 +1073,7 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved)
static int warn_limit = 10;
struct pcpu_chunk *chunk;
const char *err;
int slot, off;
int slot, off, new_alloc;
unsigned long flags;
if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
@ -1064,14 +1088,25 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved)
/* serve reserved allocations from the reserved chunk if available */
if (reserved && pcpu_reserved_chunk) {
chunk = pcpu_reserved_chunk;
if (size > chunk->contig_hint ||
pcpu_extend_area_map(chunk, &flags) < 0) {
err = "failed to extend area map of reserved chunk";
if (size > chunk->contig_hint) {
err = "alloc from reserved chunk failed";
goto fail_unlock;
}
while ((new_alloc = pcpu_need_to_extend(chunk))) {
spin_unlock_irqrestore(&pcpu_lock, flags);
if (pcpu_extend_area_map(chunk, new_alloc) < 0) {
err = "failed to extend area map of reserved chunk";
goto fail_unlock_mutex;
}
spin_lock_irqsave(&pcpu_lock, flags);
}
off = pcpu_alloc_area(chunk, size, align);
if (off >= 0)
goto area_found;
err = "alloc from reserved chunk failed";
goto fail_unlock;
}
@ -1083,14 +1118,20 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved)
if (size > chunk->contig_hint)
continue;
switch (pcpu_extend_area_map(chunk, &flags)) {
case 0:
break;
case 1:
goto restart; /* pcpu_lock dropped, restart */
default:
err = "failed to extend area map";
goto fail_unlock;
new_alloc = pcpu_need_to_extend(chunk);
if (new_alloc) {
spin_unlock_irqrestore(&pcpu_lock, flags);
if (pcpu_extend_area_map(chunk,
new_alloc) < 0) {
err = "failed to extend area map";
goto fail_unlock_mutex;
}
spin_lock_irqsave(&pcpu_lock, flags);
/*
* pcpu_lock has been dropped, need to
* restart cpu_slot list walking.
*/
goto restart;
}
off = pcpu_alloc_area(chunk, size, align);