chunk->map[] contains <offset|in-use flag> of each area. Now add a
new macro PCPU_MAP_BUSY and use it as the in-use flag to replace all
magic number '1'.
Signed-off-by: Baoquan He <b...@redhat.com>
---
mm/percpu.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index a63b4d8..8cf18dc 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -81,6 +81,15 @@
#define PCPU_EMPTY_POP_PAGES_LOW 2
#define PCPU_EMPTY_POP_PAGES_HIGH 4
+/* we use int array chunk->map[] to describe each area of chunk. Each array
+ * element is represented by one int - contains offset|1 for <offset, in use>
+ * or offset for <ofset, free> (offset need be guaranteed to be even). In the
+ * end there's a sentry entry - <total size, in-use>. So the size of the N-th
+ * area would be the offset of (N+1)-th - the offset of N-th, namely
+ * SIZEn = chunk->map[N+1]&~1 - chunk->map[N]&~1
+ * For more read-able code define PCPU_MAP_BUSY to represent in-use flag.*/
+#define PCPU_MAP_BUSY 1
+
#ifdef CONFIG_SMP
/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
#ifndef __addr_to_pcpu_ptr
@@ -328,8 +337,8 @@ static void pcpu_mem_free(void *ptr, size_t size)
*/
static int pcpu_count_occupied_pages(struct pcpu_chunk *chunk, int i)
{
- int off = chunk->map[i] & ~1;
- int end = chunk->map[i + 1] & ~1;
+ int off = chunk->map[i] & ~PCPU_MAP_BUSY;
+ int end = chunk->map[i + 1] & ~PCPU_MAP_BUSY;
if (!PAGE_ALIGNED(off) && i > 0) {
int prev = chunk->map[i - 1];
@@ -340,7 +349,7 @@ static int pcpu_count_occupied_pages(struct pcpu_chunk
*chunk, int i)
if (!PAGE_ALIGNED(end) && i + 1 < chunk->map_used) {
int next = chunk->map[i + 1];
- int nend = chunk->map[i + 2] & ~1;
+ int nend = chunk->map[i + 2] & ~PCPU_MAP_BUSY;
if (!(next & 1) && nend >= round_up(end, PAGE_SIZE))
end = round_up(end, PAGE_SIZE);
@@ -738,7 +747,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(void)
chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
chunk->map[0] = 0;
- chunk->map[1] = pcpu_unit_size | 1;
+ chunk->map[1] = pcpu_unit_size | PCPU_MAP_BUSY;
chunk->map_used = 1;
INIT_LIST_HEAD(&chunk->list);
@@ -1664,12 +1673,12 @@ int __init pcpu_setup_first_chunk(const struct
pcpu_alloc_info *ai,
}
schunk->contig_hint = schunk->free_size;
- schunk->map[0] = 1;
+ schunk->map[0] = PCPU_MAP_BUSY;
schunk->map[1] = ai->static_size;
schunk->map_used = 1;
if (schunk->free_size)
schunk->map[++schunk->map_used] = ai->static_size +
schunk->free_size;
- schunk->map[schunk->map_used] |= 1;
+ schunk->map[schunk->map_used] |= PCPU_MAP_BUSY;
/* init dynamic chunk if necessary */
if (dyn_size) {
@@ -1684,9 +1693,10 @@ int __init pcpu_setup_first_chunk(const struct
pcpu_alloc_info *ai,
dchunk->nr_populated = pcpu_unit_pages;
dchunk->contig_hint = dchunk->free_size = dyn_size;
- dchunk->map[0] = 1;
+ dchunk->map[0] = PCPU_MAP_BUSY;
dchunk->map[1] = pcpu_reserved_chunk_limit;
- dchunk->map[2] = (pcpu_reserved_chunk_limit +
dchunk->free_size) | 1;
+ dchunk->map[2] = (pcpu_reserved_chunk_limit + dchunk->free_size)
+ | PCPU_MAP_BUSY;
dchunk->map_used = 2;
}
--
2.4.3
--
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