diff options
| -rw-r--r-- | mm/percpu.c | 108 |
1 files changed, 60 insertions, 48 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index f1d0e90..7d9bc35 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -307,6 +307,50 @@ static void pcpu_chunk_addr_insert(struct pcpu_chunk *new) } /** + * pcpu_extend_area_map - extend area map for allocation + * @chunk: target chunk + * + * 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. + * + * RETURNS: + * 0 if noop, 1 if successfully extended, -errno on failure. + */ +static int pcpu_extend_area_map(struct pcpu_chunk *chunk) +{ + int new_alloc; + int *new; + size_t size; + + /* has enough? */ + if (chunk->map_alloc >= chunk->map_used + 2) + return 0; + + 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) + return -ENOMEM; + + size = chunk->map_alloc * sizeof(chunk->map[0]); + memcpy(new, chunk->map, 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); + + chunk->map_alloc = new_alloc; + chunk->map = new; + return 0; +} + +/** * pcpu_split_block - split a map block * @chunk: chunk of interest * @i: index of map block to split @@ -321,44 +365,16 @@ static void pcpu_chunk_addr_insert(struct pcpu_chunk *new) * 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. + * @chunk->map must have enough free slots to accomodate the split. */ -static int pcpu_split_block(struct pcpu_chunk *chunk, int i, int head, int tail) +static void 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; - int *new; - size_t size; - - new_alloc = PCPU_DFL_MAP_ALLOC; - while (new_alloc < target) - new_alloc *= 2; - - new = pcpu_mem_alloc(new_alloc * sizeof(new[0])); - if (!new) - return -ENOMEM; - - size = chunk->map_alloc * sizeof(chunk->map[0]); - memcpy(new, chunk->map, 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); - chunk->map_alloc = new_alloc; - chunk->map = new; - } + BUG_ON(chunk->map_alloc < chunk->map_used + nr_extra); - /* insert a new subblock */ + /* insert new subblocks */ memmove(&chunk->map[i + nr_extra], &chunk->map[i], sizeof(chunk->map[0]) * (chunk->map_used - i)); chunk->map_used += nr_extra; @@ -371,7 +387,6 @@ static int pcpu_split_block(struct pcpu_chunk *chunk, int i, int head, int tail) chunk->map[i++] -= tail; chunk->map[i] = tail; } - return 0; } /** @@ -384,8 +399,11 @@ static int pcpu_split_block(struct pcpu_chunk *chunk, int i, int head, int tail) * Note that this function only allocates the offset. It doesn't * populate or map the area. * + * @chunk->map must have at least two free slots. + * * RETURNS: - * Allocated offset in @chunk on success, -errno on failure. + * Allocated offset in @chunk on success, -1 if no matching area is + * found. */ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) { @@ -433,8 +451,7 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) /* split if warranted */ if (head || tail) { - if (pcpu_split_block(chunk, i, head, tail)) - return -ENOMEM; + pcpu_split_block(chunk, i, head, tail); if (head) { i++; off += head; @@ -461,14 +478,8 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) 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; + /* tell the upper layer that this chunk has no matching area */ + return -1; } /** @@ -755,7 +766,8 @@ 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) + if (size > chunk->contig_hint || + pcpu_extend_area_map(chunk) < 0) goto out_unlock; off = pcpu_alloc_area(chunk, size, align); if (off >= 0) @@ -768,11 +780,11 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved) list_for_each_entry(chunk, &pcpu_slot[slot], list) { if (size > chunk->contig_hint) continue; + if (pcpu_extend_area_map(chunk) < 0) + goto out_unlock; off = pcpu_alloc_area(chunk, size, align); if (off >= 0) goto area_found; - if (off != -ENOSPC) - goto out_unlock; } } |