2012-05-20 13:25:03

by Akinobu Mita

Subject: [PATCH 01/10] string: introduce memweight

memweight() is the function that counts the total number of bits set
in memory area. The memory area doesn't need to be aligned to
long-word boundary unlike bitmap_weight().

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Anders Larsen <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Laurent Pinchart <[email protected]>
Cc: [email protected]
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: [email protected]
Cc: Jan Kara <[email protected]>
Cc: [email protected]
Cc: Andrew Morton <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
---
include/linux/string.h | 3 +++
lib/string.c | 37 +++++++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index e033564..ffe0442 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -145,4 +145,7 @@ static inline bool strstarts(const char *str, const char *prefix)
return strncmp(str, prefix, strlen(prefix)) == 0;
}
#endif
+
+extern size_t memweight(const void *ptr, size_t bytes);
+
#endif /* _LINUX_STRING_H_ */
diff --git a/lib/string.c b/lib/string.c
index e5878de..c8b92a0 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -26,6 +26,7 @@
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/errno.h>
+#include <linux/bitmap.h>

#ifndef __HAVE_ARCH_STRNICMP
/**
@@ -824,3 +825,39 @@ void *memchr_inv(const void *start, int c, size_t bytes)
return check_bytes8(start, value, bytes % 8);
}
EXPORT_SYMBOL(memchr_inv);
+
+/**
+ * memweight - count the total number of bits set in memory area
+ * @ptr: pointer to the start of the area
+ * @bytes: the size of the area
+ */
+size_t memweight(const void *ptr, size_t bytes)
+{
+ size_t w = 0;
+ size_t longs;
+ union {
+ const void *ptr;
+ const unsigned char *b;
+ unsigned long address;
+ } bitmap;
+
+ for (bitmap.ptr = ptr; bytes > 0 && bitmap.address % sizeof(long);
+ bytes--, bitmap.address++)
+ w += hweight8(*bitmap.b);
+
+ for (longs = bytes / sizeof(long); longs > 0; ) {
+ size_t bits = min_t(size_t, INT_MAX & ~(BITS_PER_LONG - 1),
+ longs * BITS_PER_LONG);
+
+ w += bitmap_weight(bitmap.ptr, bits);
+ bytes -= bits / BITS_PER_BYTE;
+ bitmap.address += bits / BITS_PER_BYTE;
+ longs -= bits / BITS_PER_LONG;
+ }
+
+ for (; bytes > 0; bytes--, bitmap.address++)
+ w += hweight8(*bitmap.b);
+
+ return w;
+}
+EXPORT_SYMBOL(memweight);
--
1.7.7.6

2012-05-20 13:23:59

by Akinobu Mita

Subject: [PATCH 02/10] minixfs: use memweight()

Use memweight() to count the total number of bits clear in memory area.

Signed-off-by: Akinobu Mita <[email protected]>
---
fs/minix/bitmap.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/minix/bitmap.c b/fs/minix/bitmap.c
index 4bc50da..564f1a5 100644
--- a/fs/minix/bitmap.c
+++ b/fs/minix/bitmap.c
@@ -29,10 +29,8 @@ static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 num
unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);

while (blocks--) {
- unsigned words = blocksize / 2;
- __u16 *p = (__u16 *)(*map++)->b_data;
- while (words--)
- sum += 16 - hweight16(*p++);
+ sum += blocksize * BITS_PER_BYTE -
+ memweight((*map++)->b_data, blocksize);
}

return sum;
--
1.7.7.6

2012-05-20 13:24:21

by Akinobu Mita

Subject: [PATCH 03/10] qnx4fs: use memweight()

Use memweight() to count the total number of bits clear in memory area.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Anders Larsen <[email protected]>
---
fs/qnx4/bitmap.c | 24 +++++-------------------
1 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/fs/qnx4/bitmap.c b/fs/qnx4/bitmap.c
index 22e0d60..fc04ef1 100644
--- a/fs/qnx4/bitmap.c
+++ b/fs/qnx4/bitmap.c
@@ -17,23 +17,6 @@
#include <linux/bitops.h>
#include "qnx4.h"

-static void count_bits(register const char *bmPart, register int size,
- int *const tf)
-{
- char b;
- int tot = *tf;
-
- if (size > QNX4_BLOCK_SIZE) {
- size = QNX4_BLOCK_SIZE;
- }
- do {
- b = *bmPart++;
- tot += 8 - hweight8(b);
- size--;
- } while (size != 0);
- *tf = tot;
-}
-
unsigned long qnx4_count_free_blocks(struct super_block *sb)
{
int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
@@ -44,13 +27,16 @@ unsigned long qnx4_count_free_blocks(struct super_block *sb)
struct buffer_head *bh;

while (total < size) {
+ int bytes = min(size - total, QNX4_BLOCK_SIZE);
+
if ((bh = sb_bread(sb, start + offset)) == NULL) {
printk(KERN_ERR "qnx4: I/O error in counting free blocks\n");
break;
}
- count_bits(bh->b_data, size - total, &total_free);
+ total_free += bytes * BITS_PER_BYTE-
+ memweight(bh->b_data, bytes);
brelse(bh);
- total += QNX4_BLOCK_SIZE;
+ total += bytes;
offset++;
}

--
1.7.7.6

2012-05-20 13:25:23

by Akinobu Mita

Subject: [PATCH 10/10] ext4: use memweight()

Use memweight() to count the total number of bits clear in memory area.
This change only affects the code segments enabled by EXT4FS_DEBUG.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: [email protected]
---
fs/ext4/Makefile | 2 +-
fs/ext4/balloc.c | 3 ++-
fs/ext4/bitmap.c | 31 -------------------------------
fs/ext4/ext4.h | 3 ---
fs/ext4/ialloc.c | 4 +++-
5 files changed, 6 insertions(+), 37 deletions(-)
delete mode 100644 fs/ext4/bitmap.c

diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 56fd8f86..0caff90 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -4,7 +4,7 @@

obj-$(CONFIG_EXT4_FS) += ext4.o

-ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
+ext4-y := balloc.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o \
mmp.o indirect.o
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 4bbd07a..57e3bfb 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -584,7 +584,8 @@ ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
if (bitmap_bh == NULL)
continue;

- x = ext4_count_free(bitmap_bh, sb->s_blocksize);
+ x = sb->s_blocksize * BITS_PER_BYTE -
+ memweight(bitmap_bh->b_data, sb->s_blocksize);
printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
i, ext4_free_group_clusters(sb, gdp), x);
bitmap_count += x;
diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
deleted file mode 100644
index fa3af81..0000000
--- a/fs/ext4/bitmap.c
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
- * linux/fs/ext4/bitmap.c
- *
- * Copyright (C) 1992, 1993, 1994, 1995
- * Remy Card ([email protected])
- * Laboratoire MASI - Institut Blaise Pascal
- * Universite Pierre et Marie Curie (Paris VI)
- */
-
-#include <linux/buffer_head.h>
-#include <linux/jbd2.h>
-#include "ext4.h"
-
-#ifdef EXT4FS_DEBUG
-
-static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
-
-unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
-{
- unsigned int i, sum = 0;
-
- if (!map)
- return 0;
- for (i = 0; i < numchars; i++)
- sum += nibblemap[map->b_data[i] & 0xf] +
- nibblemap[(map->b_data[i] >> 4) & 0xf];
- return sum;
-}
-
-#endif /* EXT4FS_DEBUG */
-
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0e01e90..9c616d9 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1782,9 +1782,6 @@ struct mmpd_data {
# define ATTRIB_NORET __attribute__((noreturn))
# define NORET_AND noreturn,

-/* bitmap.c */
-extern unsigned int ext4_count_free(struct buffer_head *, unsigned);
-
/* balloc.c */
extern unsigned int ext4_block_group(struct super_block *sb,
ext4_fsblk_t blocknr);
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 409c2ee..2452bb7 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1011,7 +1011,9 @@ unsigned long ext4_count_free_inodes(struct super_block *sb)
if (!bitmap_bh)
continue;

- x = ext4_count_free(bitmap_bh, EXT4_INODES_PER_GROUP(sb) / 8);
+ x = EXT4_INODES_PER_GROUP(sb) / 8 * BITS_PER_BYTE -
+ memweight(bitmap_bh->b_data,
+ EXT4_INODES_PER_GROUP(sb) / 8);
printk(KERN_DEBUG "group %lu: stored = %d, counted = %lu\n",
(unsigned long) i, ext4_free_inodes_count(sb, gdp), x);
bitmap_count += x;
--
1.7.7.6

2012-05-20 13:25:20

by Akinobu Mita

Subject: [PATCH 09/10] ext3: use memweight()

Use memweight() to count the total number of bits clear in memory area.
This change only affects the code segments enabled by EXT3FS_DEBUG.

This also fixes printk format warning that only reveals with EXT3FS_DEBUG.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: [email protected]
---
fs/ext3/Makefile | 2 +-
fs/ext3/balloc.c | 5 +++--
fs/ext3/bitmap.c | 30 ------------------------------
fs/ext3/ext3.h | 2 --
fs/ext3/ialloc.c | 4 +++-
5 files changed, 7 insertions(+), 36 deletions(-)
delete mode 100644 fs/ext3/bitmap.c

diff --git a/fs/ext3/Makefile b/fs/ext3/Makefile
index e77766a..ce93e94 100644
--- a/fs/ext3/Makefile
+++ b/fs/ext3/Makefile
@@ -4,7 +4,7 @@

obj-$(CONFIG_EXT3_FS) += ext3.o

-ext3-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
+ext3-y := balloc.o dir.o file.o fsync.o ialloc.o inode.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o ext3_jbd.o

ext3-$(CONFIG_EXT3_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o
diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index baac1b1..676bd53 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -1804,7 +1804,8 @@ ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
if (bitmap_bh == NULL)
continue;

- x = ext3_count_free(bitmap_bh, sb->s_blocksize);
+ x = sb->s_blocksize * BITS_PER_BYTE -
+ memweight(bitmap_bh->b_data, sb->s_blocksize);
printk("group %d: stored = %d, counted = %lu\n",
i, le16_to_cpu(gdp->bg_free_blocks_count), x);
bitmap_count += x;
@@ -1812,7 +1813,7 @@ ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
brelse(bitmap_bh);
printk("ext3_count_free_blocks: stored = "E3FSBLK
", computed = "E3FSBLK", "E3FSBLK"\n",
- le32_to_cpu(es->s_free_blocks_count),
+ (ext3_fsblk_t)le32_to_cpu(es->s_free_blocks_count),
desc_count, bitmap_count);
return bitmap_count;
#else
diff --git a/fs/ext3/bitmap.c b/fs/ext3/bitmap.c
deleted file mode 100644
index 909d13e..0000000
--- a/fs/ext3/bitmap.c
+++ /dev/null
@@ -1,30 +0,0 @@
-/*
- * linux/fs/ext3/bitmap.c
- *
- * Copyright (C) 1992, 1993, 1994, 1995
- * Remy Card ([email protected])
- * Laboratoire MASI - Institut Blaise Pascal
- * Universite Pierre et Marie Curie (Paris VI)
- */
-
-#include "ext3.h"
-
-#ifdef EXT3FS_DEBUG
-
-static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
-
-unsigned long ext3_count_free (struct buffer_head * map, unsigned int numchars)
-{
- unsigned int i;
- unsigned long sum = 0;
-
- if (!map)
- return (0);
- for (i = 0; i < numchars; i++)
- sum += nibblemap[map->b_data[i] & 0xf] +
- nibblemap[(map->b_data[i] >> 4) & 0xf];
- return (sum);
-}
-
-#endif /* EXT3FS_DEBUG */
-
diff --git a/fs/ext3/ext3.h b/fs/ext3/ext3.h
index b6515fd..5c6246d 100644
--- a/fs/ext3/ext3.h
+++ b/fs/ext3/ext3.h
@@ -1029,8 +1029,6 @@ extern struct inode * ext3_orphan_get (struct super_block *, unsigned long);
extern unsigned long ext3_count_free_inodes (struct super_block *);
extern unsigned long ext3_count_dirs (struct super_block *);
extern void ext3_check_inodes_bitmap (struct super_block *);
-extern unsigned long ext3_count_free (struct buffer_head *, unsigned);
-

/* inode.c */
int ext3_forget(handle_t *handle, int is_metadata, struct inode *inode,
diff --git a/fs/ext3/ialloc.c b/fs/ext3/ialloc.c
index e3c39e4..b58c8e2 100644
--- a/fs/ext3/ialloc.c
+++ b/fs/ext3/ialloc.c
@@ -683,7 +683,9 @@ unsigned long ext3_count_free_inodes (struct super_block * sb)
if (!bitmap_bh)
continue;

- x = ext3_count_free(bitmap_bh, EXT3_INODES_PER_GROUP(sb) / 8);
+ x = EXT3_INODES_PER_GROUP(sb) / 8 * BITS_PER_BYTE -
+ memweight(bitmap_bh->b_data,
+ EXT3_INODES_PER_GROUP(sb) / 8);
printk("group %d: stored = %d, counted = %lu\n",
i, le16_to_cpu(gdp->bg_free_inodes_count), x);
bitmap_count += x;
--
1.7.7.6

2012-05-20 13:25:17

by Akinobu Mita

Subject: [PATCH 08/10] ext2: use memweight()

Use memweight() to count the total number of bits clear in memory area.
This change only affects the code segments enabled by EXT2FS_DEBUG.

This also fixes printk format warning that only reveals with EXT2FS_DEBUG.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: [email protected]
---
fs/ext2/balloc.c | 22 ++--------------------
fs/ext2/ext2.h | 1 -
fs/ext2/ialloc.c | 5 ++++-
3 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index a8cbe1b..3351731 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -1443,25 +1443,6 @@ ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
return ext2_new_blocks(inode, goal, &count, errp);
}

-#ifdef EXT2FS_DEBUG
-
-static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
-
-unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
-{
- unsigned int i;
- unsigned long sum = 0;
-
- if (!map)
- return (0);
- for (i = 0; i < numchars; i++)
- sum += nibblemap[map->b_data[i] & 0xf] +
- nibblemap[(map->b_data[i] >> 4) & 0xf];
- return (sum);
-}
-
-#endif /* EXT2FS_DEBUG */
-
unsigned long ext2_count_free_blocks (struct super_block * sb)
{
struct ext2_group_desc * desc;
@@ -1485,7 +1466,8 @@ unsigned long ext2_count_free_blocks (struct super_block * sb)
if (!bitmap_bh)
continue;

- x = ext2_count_free(bitmap_bh, sb->s_blocksize);
+ x = sb->s_blocksize * BITS_PER_BYTE -
+ memweight(bitmap_bh->b_data, sb->s_blocksize);
printk ("group %d: stored = %d, counted = %lu\n",
i, le16_to_cpu(desc->bg_free_blocks_count), x);
bitmap_count += x;
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 0b2b4db..de2a4e5 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -745,7 +745,6 @@ extern struct inode * ext2_new_inode (struct inode *, umode_t, const struct qstr
extern void ext2_free_inode (struct inode *);
extern unsigned long ext2_count_free_inodes (struct super_block *);
extern void ext2_check_inodes_bitmap (struct super_block *);
-extern unsigned long ext2_count_free (struct buffer_head *, unsigned);

/* inode.c */
extern struct inode *ext2_iget (struct super_block *, unsigned long);
diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
index 8b15cf8..82139c4 100644
--- a/fs/ext2/ialloc.c
+++ b/fs/ext2/ialloc.c
@@ -639,13 +639,16 @@ unsigned long ext2_count_free_inodes (struct super_block * sb)
if (!bitmap_bh)
continue;

- x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);
+ x = EXT2_INODES_PER_GROUP(sb) / 8 * BITS_PER_BYTE -
+ memweight(bitmap_bh->b_data,
+ EXT2_INODES_PER_GROUP(sb) / 8);
printk("group %d: stored = %d, counted = %u\n",
i, le16_to_cpu(desc->bg_free_inodes_count), x);
bitmap_count += x;
}
brelse(bitmap_bh);
printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
+ (unsigned long)
percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
desc_count, bitmap_count);
return desc_count;
--
1.7.7.6

2012-05-20 13:25:15

by Akinobu Mita

Subject: [PATCH 07/10] ocfs2: use memweight()

Use memweight to count the total number of bits set in memory area.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: [email protected]
---
fs/ocfs2/localalloc.c | 8 ++------
1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
index 210c352..a9f78c7 100644
--- a/fs/ocfs2/localalloc.c
+++ b/fs/ocfs2/localalloc.c
@@ -784,14 +784,10 @@ bail:

static u32 ocfs2_local_alloc_count_bits(struct ocfs2_dinode *alloc)
{
- int i;
- u8 *buffer;
- u32 count = 0;
+ u32 count;
struct ocfs2_local_alloc *la = OCFS2_LOCAL_ALLOC(alloc);

- buffer = la->la_bitmap;
- for (i = 0; i < le16_to_cpu(la->la_size); i++)
- count += hweight8(buffer[i]);
+ count = memweight(la->la_bitmap, le16_to_cpu(la->la_size));

trace_ocfs2_local_alloc_count_bits(count);
return count;
--
1.7.7.6

2012-05-20 13:25:12

by Akinobu Mita

Subject: [PATCH 06/10] video/uvc: use memweight()

Use memweight() to count the total number of bits set in memory area.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: [email protected]
---
drivers/media/video/uvc/uvc_ctrl.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index 0efd3b1..8683be0 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -1851,7 +1851,7 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
/* Walk the entities list and instantiate controls */
list_for_each_entry(entity, &dev->entities, list) {
struct uvc_control *ctrl;
- unsigned int bControlSize = 0, ncontrols = 0;
+ unsigned int bControlSize = 0, ncontrols;
__u8 *bmControls = NULL;

if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT) {
@@ -1869,8 +1869,7 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
uvc_ctrl_prune_entity(dev, entity);

/* Count supported controls and allocate the controls array */
- for (i = 0; i < bControlSize; ++i)
- ncontrols += hweight8(bmControls[i]);
+ ncontrols = memweight(bmControls, bControlSize);
if (ncontrols == 0)
continue;

--
1.7.7.6

2012-05-20 13:25:09

by Akinobu Mita

Subject: [PATCH 05/10] affs: use memweight()

Use memweight() to count the total number of bits set in memory area.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: [email protected]
---
fs/affs/bitmap.c | 28 ++--------------------------
1 files changed, 2 insertions(+), 26 deletions(-)

diff --git a/fs/affs/bitmap.c b/fs/affs/bitmap.c
index 3e26271..3dfdcd2 100644
--- a/fs/affs/bitmap.c
+++ b/fs/affs/bitmap.c
@@ -10,30 +10,6 @@
#include <linux/slab.h>
#include "affs.h"

-/* This is, of course, shamelessly stolen from fs/minix */
-
-static const int nibblemap[] = { 0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4 };
-
-static u32
-affs_count_free_bits(u32 blocksize, const void *data)
-{
- const u32 *map;
- u32 free;
- u32 tmp;
-
- map = data;
- free = 0;
- for (blocksize /= 4; blocksize > 0; blocksize--) {
- tmp = *map++;
- while (tmp) {
- free += nibblemap[tmp & 0xf];
- tmp >>= 4;
- }
- }
-
- return free;
-}
-
u32
affs_count_free_blocks(struct super_block *sb)
{
@@ -317,7 +293,7 @@ int affs_init_bitmap(struct super_block *sb, int *flags)
goto out;
}
pr_debug("AFFS: read bitmap block %d: %d\n", blk, bm->bm_key);
- bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
+ bm->bm_free = memweight(bh->b_data + 4, sb->s_blocksize - 4);

/* Don't try read the extension if this is the last block,
* but we also need the right bm pointer below
@@ -367,7 +343,7 @@ int affs_init_bitmap(struct super_block *sb, int *flags)

/* recalculate bitmap count for last block */
bm--;
- bm->bm_free = affs_count_free_bits(sb->s_blocksize - 4, bh->b_data + 4);
+ bm->bm_free = memweight(bh->b_data + 4, sb->s_blocksize - 4);

out:
affs_brelse(bh);
--
1.7.7.6

2012-05-20 13:25:07

by Akinobu Mita

Subject: [PATCH 04/10] dm-log: use memweight()

Use memweight() to count the total number of bits set in memory area.

Signed-off-by: Akinobu Mita <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: [email protected]
---
drivers/md/dm-log.c | 13 ++-----------
1 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 65ebaeb..627d191 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -571,16 +571,6 @@ static void disk_dtr(struct dm_dirty_log *log)
destroy_log_context(lc);
}

-static int count_bits32(uint32_t *addr, unsigned size)
-{
- int count = 0, i;
-
- for (i = 0; i < size; i++) {
- count += hweight32(*(addr+i));
- }
- return count;
-}
-
static void fail_log_device(struct log_c *lc)
{
if (lc->log_dev_failed)
@@ -629,7 +619,8 @@ static int disk_resume(struct dm_dirty_log *log)

/* copy clean across to sync */
memcpy(lc->sync_bits, lc->clean_bits, size);
- lc->sync_count = count_bits32(lc->clean_bits, lc->bitset_uint32_count);
+ lc->sync_count = memweight(lc->clean_bits,
+ lc->bitset_uint32_count * sizeof(uint32_t));
lc->sync_search = 0;

/* set the correct number of regions in the header */
--
1.7.7.6

2012-05-20 15:58:13

by Anders Larsen

Subject: Re: [PATCH 03/10] qnx4fs: use memweight()

On 2012-05-20 15:23:16, Akinobu Mita wrote:
> Use memweight() to count the total number of bits clear in memory
> area.
>
> Signed-off-by: Akinobu Mita <[email protected]>
> Cc: Anders Larsen <[email protected]>
> ---
> fs/qnx4/bitmap.c | 24 +++++-------------------
> 1 files changed, 5 insertions(+), 19 deletions(-)
>
> diff --git a/fs/qnx4/bitmap.c b/fs/qnx4/bitmap.c
> index 22e0d60..fc04ef1 100644
> --- a/fs/qnx4/bitmap.c
> +++ b/fs/qnx4/bitmap.c
> @@ -17,23 +17,6 @@
> #include <linux/bitops.h>
> #include "qnx4.h"
>
> -static void count_bits(register const char *bmPart, register int
> size,
> - int *const tf)
> -{
> - char b;
> - int tot = *tf;
> -
> - if (size > QNX4_BLOCK_SIZE) {
> - size = QNX4_BLOCK_SIZE;
> - }
> - do {
> - b = *bmPart++;
> - tot += 8 - hweight8(b);
> - size--;
> - } while (size != 0);
> - *tf = tot;
> -}
> -
> unsigned long qnx4_count_free_blocks(struct super_block *sb)
> {
> int start =
> le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
> @@ -44,13 +27,16 @@ unsigned long qnx4_count_free_blocks(struct
> super_block *sb)
> struct buffer_head *bh;
>
> while (total < size) {
> + int bytes = min(size - total, QNX4_BLOCK_SIZE);
> +
> if ((bh = sb_bread(sb, start + offset)) == NULL) {
> printk(KERN_ERR "qnx4: I/O error in counting
> free blocks\n");
> break;
> }
> - count_bits(bh->b_data, size - total, &total_free);
> + total_free += bytes * BITS_PER_BYTE-

due to the missing whitespace after the macro I had to read that
statement
three times to comprehend it (which was probably good, since that's the
beef ;)

> + memweight(bh->b_data, bytes);
> brelse(bh);
> - total += QNX4_BLOCK_SIZE;
> + total += bytes;
> offset++;
> }

Other than that,
Acked-by: Anders Larsen <[email protected]>

Cheers
Anders

2012-05-20 20:46:26

by Laurent Pinchart

Subject: Re: [PATCH 06/10] video/uvc: use memweight()

Hi Akinobu,

Thank you for the patch.

On Sunday 20 May 2012 22:23:19 Akinobu Mita wrote:
> Use memweight() to count the total number of bits set in memory area.
>
> Signed-off-by: Akinobu Mita <[email protected]>
> Cc: Laurent Pinchart <[email protected]>
> Cc: [email protected]

Laurent Pinchart <[email protected]>

> ---
> drivers/media/video/uvc/uvc_ctrl.c | 5 ++---
> 1 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/video/uvc/uvc_ctrl.c
> b/drivers/media/video/uvc/uvc_ctrl.c index 0efd3b1..8683be0 100644
> --- a/drivers/media/video/uvc/uvc_ctrl.c
> +++ b/drivers/media/video/uvc/uvc_ctrl.c
> @@ -1851,7 +1851,7 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
> /* Walk the entities list and instantiate controls */
> list_for_each_entry(entity, &dev->entities, list) {
> struct uvc_control *ctrl;
> - unsigned int bControlSize = 0, ncontrols = 0;
> + unsigned int bControlSize = 0, ncontrols;
> __u8 *bmControls = NULL;
>
> if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT) {
> @@ -1869,8 +1869,7 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
> uvc_ctrl_prune_entity(dev, entity);
>
> /* Count supported controls and allocate the controls array */
> - for (i = 0; i < bControlSize; ++i)
> - ncontrols += hweight8(bmControls[i]);
> + ncontrols = memweight(bmControls, bControlSize);
> if (ncontrols == 0)
> continue;

--
Regards,

Laurent Pinchart

2012-05-21 12:00:01

by Akinobu Mita

Subject: Re: [PATCH 03/10] qnx4fs: use memweight()

2012/5/21 Anders Larsen <[email protected]>:

>> @@ -44,13 +27,16 @@ unsigned long qnx4_count_free_blocks(struct
>> super_block *sb)
>> ? ? ? ?struct buffer_head *bh;
>>
>> ? ? ? ?while (total < size) {
>> + ? ? ? ? ? ? ? int bytes = min(size - total, QNX4_BLOCK_SIZE);
>> +
>> ? ? ? ? ? ? ? ?if ((bh = sb_bread(sb, start + offset)) == NULL) {
>> ? ? ? ? ? ? ? ? ? ? ? ?printk(KERN_ERR "qnx4: I/O error in counting free
>> blocks\n");
>> ? ? ? ? ? ? ? ? ? ? ? ?break;
>> ? ? ? ? ? ? ? ?}
>> - ? ? ? ? ? ? ? count_bits(bh->b_data, size - total, &total_free);
>> + ? ? ? ? ? ? ? total_free += bytes * BITS_PER_BYTE-
>
>
> due to the missing whitespace after the macro I had to read that statement
> three times to comprehend it (which was probably good, since that's the beef
> ;)

Oh, checkpatch.pl also couldn't detect it.

>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? memweight(bh->b_data, bytes);
>> ? ? ? ? ? ? ? ?brelse(bh);
>> - ? ? ? ? ? ? ? total += QNX4_BLOCK_SIZE;
>> + ? ? ? ? ? ? ? total += bytes;
>> ? ? ? ? ? ? ? ?offset++;
>> ? ? ? ?}
>
>
> Other than that,
> Acked-by: Anders Larsen <[email protected]>

Thanks.

2012-05-21 12:03:13

by Akinobu Mita

Subject: Re: [PATCH 06/10] video/uvc: use memweight()

2012/5/21 Laurent Pinchart <[email protected]>:
> Hi Akinobu,
>
> Thank you for the patch.
>
> On Sunday 20 May 2012 22:23:19 Akinobu Mita wrote:
>> Use memweight() to count the total number of bits set in memory area.
>>
>> Signed-off-by: Akinobu Mita <[email protected]>
>> Cc: Laurent Pinchart <[email protected]>
>> Cc: [email protected]
>
> Laurent Pinchart <[email protected]>

You meant Acked-by, didn't you?

2012-05-21 12:18:10

by Laurent Pinchart

Subject: Re: [PATCH 06/10] video/uvc: use memweight()

Hi Akinobu,

On Monday 21 May 2012 21:03:10 Akinobu Mita wrote:
> 2012/5/21 Laurent Pinchart <[email protected]>:
> > Hi Akinobu,
> >
> > Thank you for the patch.
> >
> > On Sunday 20 May 2012 22:23:19 Akinobu Mita wrote:
> >> Use memweight() to count the total number of bits set in memory area.
> >>
> >> Signed-off-by: Akinobu Mita <[email protected]>
> >> Cc: Laurent Pinchart <[email protected]>
> >> Cc: [email protected]
> >
> > Laurent Pinchart <[email protected]>
>
> You meant Acked-by, didn't you?

Oops, yes, sorry. Bad copy & paste.

--
Regards,

Laurent Pinchart

2012-05-23 09:21:37

by Jan Kara

Subject: Re: [PATCH 01/10] string: introduce memweight

On Sun 20-05-12 22:23:14, Akinobu Mita wrote:
> memweight() is the function that counts the total number of bits set
> in memory area. The memory area doesn't need to be aligned to
> long-word boundary unlike bitmap_weight().
Thanks for the patch. I have some comments below.

> Signed-off-by: Akinobu Mita <[email protected]>
> Cc: Anders Larsen <[email protected]>
> Cc: Alasdair Kergon <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: Laurent Pinchart <[email protected]>
> Cc: [email protected]
> Cc: Mark Fasheh <[email protected]>
> Cc: Joel Becker <[email protected]>
> Cc: [email protected]
> Cc: Jan Kara <[email protected]>
> Cc: [email protected]
> Cc: Andrew Morton <[email protected]>
> Cc: Andreas Dilger <[email protected]>
> Cc: "Theodore Ts'o" <[email protected]>
> ---
> include/linux/string.h | 3 +++
> lib/string.c | 37 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/string.h b/include/linux/string.h
> index e033564..ffe0442 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -145,4 +145,7 @@ static inline bool strstarts(const char *str, const char *prefix)
> return strncmp(str, prefix, strlen(prefix)) == 0;
> }
> #endif
> +
> +extern size_t memweight(const void *ptr, size_t bytes);
> +
> #endif /* _LINUX_STRING_H_ */
> diff --git a/lib/string.c b/lib/string.c
> index e5878de..c8b92a0 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -26,6 +26,7 @@
> #include <linux/export.h>
> #include <linux/bug.h>
> #include <linux/errno.h>
> +#include <linux/bitmap.h>
>
> #ifndef __HAVE_ARCH_STRNICMP
> /**
> @@ -824,3 +825,39 @@ void *memchr_inv(const void *start, int c, size_t bytes)
> return check_bytes8(start, value, bytes % 8);
> }
> EXPORT_SYMBOL(memchr_inv);
> +
> +/**
> + * memweight - count the total number of bits set in memory area
> + * @ptr: pointer to the start of the area
> + * @bytes: the size of the area
> + */
> +size_t memweight(const void *ptr, size_t bytes)
> +{
> + size_t w = 0;
> + size_t longs;
> + union {
> + const void *ptr;
> + const unsigned char *b;
> + unsigned long address;
> + } bitmap;
Ugh, this is ugly and mostly unnecessary. Just use "const unsigned char
*bitmap".

> +
> + for (bitmap.ptr = ptr; bytes > 0 && bitmap.address % sizeof(long);
> + bytes--, bitmap.address++)
> + w += hweight8(*bitmap.b);
This can be:
count = ((unsigned long)bitmap) % sizeof(long);
while (count--) {
w += hweight(*bitmap);
bitmap++;
bytes--;
}
> +
> + for (longs = bytes / sizeof(long); longs > 0; ) {
> + size_t bits = min_t(size_t, INT_MAX & ~(BITS_PER_LONG - 1),
> + longs * BITS_PER_LONG);
I find it highly unlikely that someone would have such a large bitmap
(256 MB or more on 32-bit). Also the condition as you wrote it can just
overflow so it won't have the desired effect. Just do
BUG_ON(longs >= ULONG_MAX / BITS_PER_LONG);
and remove the loop completely. If someone comes with such a huge bitmap,
the code can be modified easily (after really closely inspecting whether
such a huge bitmap is really well justified).

> +
> + w += bitmap_weight(bitmap.ptr, bits);
> + bytes -= bits / BITS_PER_BYTE;
> + bitmap.address += bits / BITS_PER_BYTE;
> + longs -= bits / BITS_PER_LONG;
> + }
> +
> + for (; bytes > 0; bytes--, bitmap.address++)
> + w += hweight8(*bitmap.b);
> +
> + return w;
> +}
> +EXPORT_SYMBOL(memweight);

Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR

2012-05-23 12:12:21

by Akinobu Mita

Subject: Re: [PATCH 01/10] string: introduce memweight

2012/5/23 Jan Kara <[email protected]>:
> On Sun 20-05-12 22:23:14, Akinobu Mita wrote:
>> memweight() is the function that counts the total number of bits set
>> in memory area. ?The memory area doesn't need to be aligned to
>> long-word boundary unlike bitmap_weight().
> ?Thanks for the patch. I have some comments below.

Thanks for the review.

>> @@ -824,3 +825,39 @@ void *memchr_inv(const void *start, int c, size_t bytes)
>> ? ? ? return check_bytes8(start, value, bytes % 8);
>> ?}
>> ?EXPORT_SYMBOL(memchr_inv);
>> +
>> +/**
>> + * memweight - count the total number of bits set in memory area
>> + * @ptr: pointer to the start of the area
>> + * @bytes: the size of the area
>> + */
>> +size_t memweight(const void *ptr, size_t bytes)
>> +{
>> + ? ? size_t w = 0;
>> + ? ? size_t longs;
>> + ? ? union {
>> + ? ? ? ? ? ? const void *ptr;
>> + ? ? ? ? ? ? const unsigned char *b;
>> + ? ? ? ? ? ? unsigned long address;
>> + ? ? } bitmap;
> ?Ugh, this is ugly and mostly unnecessary. Just use "const unsigned char
> *bitmap".
>
>> +
>> + ? ? for (bitmap.ptr = ptr; bytes > 0 && bitmap.address % sizeof(long);
>> + ? ? ? ? ? ? ? ? ? ? bytes--, bitmap.address++)
>> + ? ? ? ? ? ? w += hweight8(*bitmap.b);
> ?This can be:
> ? ? ? ?count = ((unsigned long)bitmap) % sizeof(long);

The count should be the size of unaligned area and it can be greater than
bytes. So

count = min(bytes,
sizeof(long) - ((unsigned long)bitmap) % sizeof(long));

> ? ? ? ?while (count--) {
> ? ? ? ? ? ? ? ?w += hweight(*bitmap);
> ? ? ? ? ? ? ? ?bitmap++;
> ? ? ? ? ? ? ? ?bytes--;
> ? ? ? ?}
>> +
>> + ? ? for (longs = bytes / sizeof(long); longs > 0; ) {
>> + ? ? ? ? ? ? size_t bits = min_t(size_t, INT_MAX & ~(BITS_PER_LONG - 1),
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? longs * BITS_PER_LONG);
> ?I find it highly unlikely that someone would have such a large bitmap
> (256 MB or more on 32-bit). Also the condition as you wrote it can just
> overflow so it won't have the desired effect. Just do
> ? ? ? ?BUG_ON(longs >= ULONG_MAX / BITS_PER_LONG);

The bits argument of bitmap_weight() is int type. So this should be

BUG_ON(longs >= INT_MAX / BITS_PER_LONG);

> and remove the loop completely. If someone comes with such a huge bitmap,
> the code can be modified easily (after really closely inspecting whether
> such a huge bitmap is really well justified).

size_t memweight(const void *ptr, size_t bytes)
{
size_t w = 0;
size_t longs;
const unsigned char *bitmap = ptr;

for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
bytes--, bitmap++)
w += hweight8(*bitmap);

longs = bytes / sizeof(long);
BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
w += bitmap_weight((unsigned long *)bitmap, longs * BITS_PER_LONG);
bytes -= longs * sizeof(long);
bitmap += longs * sizeof(long);

for (; bytes > 0; bytes--, bitmap++)
w += hweight8(*bitmap);

return w;
}

2012-05-23 12:30:11

by Jan Kara

Subject: Re: [PATCH 01/10] string: introduce memweight

On Wed 23-05-12 21:12:18, Akinobu Mita wrote:
> 2012/5/23 Jan Kara <[email protected]>:
> > On Sun 20-05-12 22:23:14, Akinobu Mita wrote:
> >> memweight() is the function that counts the total number of bits set
> >> in memory area. ?The memory area doesn't need to be aligned to
> >> long-word boundary unlike bitmap_weight().
> > ?Thanks for the patch. I have some comments below.
>
> Thanks for the review.
>
> >> @@ -824,3 +825,39 @@ void *memchr_inv(const void *start, int c, size_t bytes)
> >> ? ? ? return check_bytes8(start, value, bytes % 8);
> >> ?}
> >> ?EXPORT_SYMBOL(memchr_inv);
> >> +
> >> +/**
> >> + * memweight - count the total number of bits set in memory area
> >> + * @ptr: pointer to the start of the area
> >> + * @bytes: the size of the area
> >> + */
> >> +size_t memweight(const void *ptr, size_t bytes)
> >> +{
> >> + ? ? size_t w = 0;
> >> + ? ? size_t longs;
> >> + ? ? union {
> >> + ? ? ? ? ? ? const void *ptr;
> >> + ? ? ? ? ? ? const unsigned char *b;
> >> + ? ? ? ? ? ? unsigned long address;
> >> + ? ? } bitmap;
> > ?Ugh, this is ugly and mostly unnecessary. Just use "const unsigned char
> > *bitmap".
> >
> >> +
> >> + ? ? for (bitmap.ptr = ptr; bytes > 0 && bitmap.address % sizeof(long);
> >> + ? ? ? ? ? ? ? ? ? ? bytes--, bitmap.address++)
> >> + ? ? ? ? ? ? w += hweight8(*bitmap.b);
> > ?This can be:
> > ? ? ? ?count = ((unsigned long)bitmap) % sizeof(long);
>
> The count should be the size of unaligned area and it can be greater than
> bytes. So
>
> count = min(bytes,
> sizeof(long) - ((unsigned long)bitmap) % sizeof(long));
You are right, I didn't quite think this through.

> > ? ? ? ?while (count--) {
> > ? ? ? ? ? ? ? ?w += hweight(*bitmap);
> > ? ? ? ? ? ? ? ?bitmap++;
> > ? ? ? ? ? ? ? ?bytes--;
> > ? ? ? ?}
> >> +
> >> + ? ? for (longs = bytes / sizeof(long); longs > 0; ) {
> >> + ? ? ? ? ? ? size_t bits = min_t(size_t, INT_MAX & ~(BITS_PER_LONG - 1),
> >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? longs * BITS_PER_LONG);
> > ?I find it highly unlikely that someone would have such a large bitmap
> > (256 MB or more on 32-bit). Also the condition as you wrote it can just
> > overflow so it won't have the desired effect. Just do
> > ? ? ? ?BUG_ON(longs >= ULONG_MAX / BITS_PER_LONG);
>
> The bits argument of bitmap_weight() is int type. So this should be
>
> BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
OK, I didn't check and thought it's size_t.

> > and remove the loop completely. If someone comes with such a huge bitmap,
> > the code can be modified easily (after really closely inspecting whether
> > such a huge bitmap is really well justified).
>
> size_t memweight(const void *ptr, size_t bytes)
> {
> size_t w = 0;
> size_t longs;
> const unsigned char *bitmap = ptr;
>
> for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
> bytes--, bitmap++)
> w += hweight8(*bitmap);
>
> longs = bytes / sizeof(long);
> BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
> w += bitmap_weight((unsigned long *)bitmap, longs * BITS_PER_LONG);
> bytes -= longs * sizeof(long);
> bitmap += longs * sizeof(long);
>
> for (; bytes > 0; bytes--, bitmap++)
> w += hweight8(*bitmap);
>
> return w;
> }
Yup, this looks much more readable. Thanks!

Honza

--
Jan Kara <[email protected]>
SUSE Labs, CR

2012-05-23 13:16:06

by Matthew Wilcox

Subject: Re: [PATCH 01/10] string: introduce memweight

On Wed, May 23, 2012 at 09:12:18PM +0900, Akinobu Mita wrote:
> size_t memweight(const void *ptr, size_t bytes)

Why should this return size_t instead of unsigned long?

> {
> size_t w = 0;
> size_t longs;
> const unsigned char *bitmap = ptr;
>
> for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
> bytes--, bitmap++)
> w += hweight8(*bitmap);
>
> longs = bytes / sizeof(long);
> BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
> w += bitmap_weight((unsigned long *)bitmap, longs * BITS_PER_LONG);
> bytes -= longs * sizeof(long);
> bitmap += longs * sizeof(long);
>
> for (; bytes > 0; bytes--, bitmap++)
> w += hweight8(*bitmap);
>
> return w;
> }

bitmap_weight copes with a bitmask that isn't a multiple of BITS_PER_LONG
in size already. So I think this can be done as:

unsigned long memweight(const void *s, size_t n)
{
const unsigned char *ptr = s;
unsigned long r = 0;

while (n > 0 && (unsigned long)ptr % sizeof(long)) {
r += hweight8(*ptr);
n--;
ptr++;
}

BUG_ON(n >= INT_MAX / 8)

return r + bitmap_weight((unsigned long *)ptr, n * 8);
}

--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."

2012-05-24 11:54:20

by Akinobu Mita

Subject: Re: [PATCH 01/10] string: introduce memweight

2012/5/23 Matthew Wilcox <[email protected]>:
> On Wed, May 23, 2012 at 09:12:18PM +0900, Akinobu Mita wrote:
>> size_t memweight(const void *ptr, size_t bytes)
>
> Why should this return size_t instead of unsigned long?

I just use the same type as the bytes argument without mature
consideration. If unsigned long is better than size_t, I'll
change the return type.

>> {
>> ? ? ? size_t w = 0;
>> ? ? ? size_t longs;
>> ? ? ? const unsigned char *bitmap = ptr;
>>
>> ? ? ? for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
>> ? ? ? ? ? ? ? ? ? ? ? bytes--, bitmap++)
>> ? ? ? ? ? ? ? w += hweight8(*bitmap);
>>
>> ? ? ? longs = bytes / sizeof(long);
>> ? ? ? BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
>> ? ? ? w += bitmap_weight((unsigned long *)bitmap, longs * BITS_PER_LONG);
>> ? ? ? bytes -= longs * sizeof(long);
>> ? ? ? bitmap += longs * sizeof(long);
>>
>> ? ? ? for (; bytes > 0; bytes--, bitmap++)
>> ? ? ? ? ? ? ? w += hweight8(*bitmap);
>>
>> ? ? ? return w;
>> }
>
> bitmap_weight copes with a bitmask that isn't a multiple of BITS_PER_LONG
> in size already. ?So I think this can be done as:
>
> unsigned long memweight(const void *s, size_t n)
> {
> ? ? ? ?const unsigned char *ptr = s;
> ? ? ? ?unsigned long r = 0;
>
> ? ? ? ?while (n > 0 && (unsigned long)ptr % sizeof(long)) {
> ? ? ? ? ? ? ? ?r += hweight8(*ptr);
> ? ? ? ? ? ? ? ?n--;
> ? ? ? ? ? ? ? ?ptr++;
> ? ? ? ?}
>
> ? ? ? ?BUG_ON(n >= INT_MAX / 8)
>
> ? ? ? ?return r + bitmap_weight((unsigned long *)ptr, n * 8);
> }

This works perfectly on little-endian machines. But it doesn't work
on big-endian machines, if the bottom edge of memory area is not
aligned on long word boundary.