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author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-11-14 23:59:06 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-11-14 23:59:06 +0300 |
commit | e0a2af1e60ae89b18ef3afbf655f096564751045 (patch) | |
tree | fe31737835ea20c2933793fc7fbb38afffc130c2 /mm | |
parent | 0283243849e88f864a059783b29346cbf1e0b8e8 (diff) | |
parent | 833af8427be4b217b5bc522f61afdbd3f1d282c2 (diff) | |
download | linux-e0a2af1e60ae89b18ef3afbf655f096564751045.tar.xz |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* '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
Diffstat (limited to 'mm')
-rw-r--r-- | mm/percpu.c | 121 |
1 files changed, 81 insertions, 40 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index d90797160c2a..5adfc268b408 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -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); + + if (new_alloc <= chunk->map_alloc) + goto out_unlock; - size = chunk->map_alloc * sizeof(chunk->map[0]); - memcpy(new, chunk->map, size); + 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 @@ restart: 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); |