[PATCH 10/12] percpu: make pcpu_block_md generic

[Dennis Zhou]

In reality, a chunk is just a block covering a larger number of bits.
The hints themselves are one in the same. Rather than maintaining the
hints separately, first introduce nr_bits to genericize
pcpu_block_update() to correctly maintain block->right_free. The next
patch will convert chunk hints to be managed as a pcpu_block_md.

Signed-off-by: Dennis Zhou <den...@kernel.org>
---
 mm/percpu-internal.h |  1 +
 mm/percpu.c          | 20 +++++++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index ec58b244545d..119bd1119aa7 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -28,6 +28,7 @@ struct pcpu_block_md {
        int                     right_free;     /* size of free space along
                                                   the right side of the block 
*/
        int                     first_free;     /* block position of first free 
*/
+       int                     nr_bits;        /* total bits responsible for */
 };
 
 struct pcpu_chunk {
diff --git a/mm/percpu.c b/mm/percpu.c
index e51c151ed692..7cdf14c242de 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -658,7 +658,7 @@ static void pcpu_block_update(struct pcpu_block_md *block, 
int start, int end)
        if (start == 0)
                block->left_free = contig;
 
-       if (end == PCPU_BITMAP_BLOCK_BITS)
+       if (end == block->nr_bits)
                block->right_free = contig;
 
        if (contig > block->contig_hint) {
@@ -1271,18 +1271,24 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, 
int off)
        pcpu_chunk_relocate(chunk, oslot);
 }
 
+static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
+{
+       block->scan_hint = 0;
+       block->contig_hint = nr_bits;
+       block->left_free = nr_bits;
+       block->right_free = nr_bits;
+       block->first_free = 0;
+       block->nr_bits = nr_bits;
+}
+
 static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
 {
        struct pcpu_block_md *md_block;
 
        for (md_block = chunk->md_blocks;
             md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
-            md_block++) {
-               md_block->scan_hint = 0;
-               md_block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
-               md_block->left_free = PCPU_BITMAP_BLOCK_BITS;
-               md_block->right_free = PCPU_BITMAP_BLOCK_BITS;
-       }
+            md_block++)
+               pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
 }
 
 /**
-- 
2.17.1