[PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Akinobu Mita]

This introduces new bitmap functions:

bitmap_set: Set specified bit area
bitmap_clear: Clear specified bit area
bitmap_find_next_zero_area: Find free bit area

These are stolen from iommu helper.

I changed the return value of bitmap_find_next_zero_area if there is
no zero area.

find_next_zero_area in iommu helper: returns -1
bitmap_find_next_zero_area: return >= bitmap size

Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@ozlabs.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Lothar Wassmann <LW@KARO-electronics.de>
Cc: linux-usb@vger.kernel.org
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Cc: netdev@vger.kernel.org
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: linux-altix@sgi.com
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 include/linux/bitmap.h |   11 +++++++++++
 lib/bitmap.c           |   47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 0 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 756d78b..daf8c48 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -42,6 +42,9 @@
  * bitmap_empty(src, nbits)			Are all bits zero in *src?
  * bitmap_full(src, nbits)			Are all bits set in *src?
  * bitmap_weight(src, nbits)			Hamming Weight: number set bits
+ * bitmap_set(dst, pos, nbits)			Set specified bit area
+ * bitmap_clear(dst, pos, nbits)		Clear specified bit area
+ * bitmap_find_next_zero_area(buf, len, pos, n, mask)	Find bit free area
  * bitmap_shift_right(dst, src, n, nbits)	*dst = *src >> n
  * bitmap_shift_left(dst, src, n, nbits)	*dst = *src << n
  * bitmap_remap(dst, src, old, new, nbits)	*dst = map(old, new)(src)
@@ -108,6 +111,14 @@ extern int __bitmap_subset(const unsigned long *bitmap1,
 			const unsigned long *bitmap2, int bits);
 extern int __bitmap_weight(const unsigned long *bitmap, int bits);
 
+extern void bitmap_set(unsigned long *map, int i, int len);
+extern void bitmap_clear(unsigned long *map, int start, int nr);
+extern unsigned long bitmap_find_next_zero_area(unsigned long *map,
+					 unsigned long size,
+					 unsigned long start,
+					 unsigned int nr,
+					 unsigned long align_mask);
+
 extern int bitmap_scnprintf(char *buf, unsigned int len,
 			const unsigned long *src, int nbits);
 extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 7025658..95070fa 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -271,6 +271,53 @@ int __bitmap_weight(const unsigned long *bitmap, int bits)
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
+void bitmap_set(unsigned long *map, int i, int len)
+{
+	int end = i + len;
+
+	while (i < end) {
+		__set_bit(i, map);
+		i++;
+	}
+}
+EXPORT_SYMBOL(bitmap_set);
+
+void bitmap_clear(unsigned long *map, int start, int nr)
+{
+	int end = start + nr;
+
+	while (start < end) {
+		__clear_bit(start, map);
+		start++;
+	}
+}
+EXPORT_SYMBOL(bitmap_clear);
+
+unsigned long bitmap_find_next_zero_area(unsigned long *map,
+					 unsigned long size,
+					 unsigned long start,
+					 unsigned int nr,
+					 unsigned long align_mask)
+{
+	unsigned long index, end, i;
+again:
+	index = find_next_zero_bit(map, size, start);
+
+	/* Align allocation */
+	index = (index + align_mask) & ~align_mask;
+
+	end = index + nr;
+	if (end >= size)
+		return end;
+	i = find_next_bit(map, end, index);
+	if (i < end) {
+		start = i + 1;
+		goto again;
+	}
+	return index;
+}
+EXPORT_SYMBOL(bitmap_find_next_zero_area);
+
 /*
  * Bitmap printing & parsing functions: first version by Bill Irwin,
  * second version by Paul Jackson, third by Joe Korty.
-- 
1.5.4.3

[PATCH 5/8] mlx4: Use bitmap_find_next_zero_area

[Akinobu Mita]

Cc: Roland Dreier <rolandd@cisco.com>
Cc: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Cc: netdev@vger.kernel.org
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 drivers/net/mlx4/alloc.c |   37 ++++---------------------------------
 1 files changed, 4 insertions(+), 33 deletions(-)

diff --git a/drivers/net/mlx4/alloc.c b/drivers/net/mlx4/alloc.c
index ad95d5f..8c85156 100644
--- a/drivers/net/mlx4/alloc.c
+++ b/drivers/net/mlx4/alloc.c
@@ -72,35 +72,6 @@ void mlx4_bitmap_free(struct mlx4_bitmap *bitmap, u32 obj)
 	mlx4_bitmap_free_range(bitmap, obj, 1);
 }
 
-static unsigned long find_aligned_range(unsigned long *bitmap,
-					u32 start, u32 nbits,
-					int len, int align)
-{
-	unsigned long end, i;
-
-again:
-	start = ALIGN(start, align);
-
-	while ((start < nbits) && test_bit(start, bitmap))
-		start += align;
-
-	if (start >= nbits)
-		return -1;
-
-	end = start+len;
-	if (end > nbits)
-		return -1;
-
-	for (i = start + 1; i < end; i++) {
-		if (test_bit(i, bitmap)) {
-			start = i + 1;
-			goto again;
-		}
-	}
-
-	return start;
-}
-
 u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
 {
 	u32 obj, i;
@@ -110,13 +81,13 @@ u32 mlx4_bitmap_alloc_range(struct mlx4_bitmap *bitmap, int cnt, int align)
 
 	spin_lock(&bitmap->lock);
 
-	obj = find_aligned_range(bitmap->table, bitmap->last,
-				 bitmap->max, cnt, align);
+	obj = bitmap_find_next_zero_area(bitmap->table, bitmap->max,
+				bitmap->last, cnt, align - 1);
 	if (obj >= bitmap->max) {
 		bitmap->top = (bitmap->top + bitmap->max + bitmap->reserved_top)
 				& bitmap->mask;
-		obj = find_aligned_range(bitmap->table, 0, bitmap->max,
-					 cnt, align);
+		obj = bitmap_find_next_zero_area(bitmap->table, bitmap->max,
+						0, cnt, align - 1);
 	}
 
 	if (obj < bitmap->max) {
-- 
1.5.4.3

Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Andrew Morton]

On Fri,  9 Oct 2009 17:29:15 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:

> This introduces new bitmap functions:
> 
> bitmap_set: Set specified bit area
> bitmap_clear: Clear specified bit area
> bitmap_find_next_zero_area: Find free bit area
> 
> These are stolen from iommu helper.
> 
> I changed the return value of bitmap_find_next_zero_area if there is
> no zero area.
> 
> find_next_zero_area in iommu helper: returns -1
> bitmap_find_next_zero_area: return >= bitmap size

I'll plan to merge this patch into 2.6.32 so we can trickle all the
other patches into subsystems in an orderly fashion.

> +void bitmap_set(unsigned long *map, int i, int len)
> +{
> +	int end = i + len;
> +
> +	while (i < end) {
> +		__set_bit(i, map);
> +		i++;
> +	}
> +}

This is really inefficient, isn't it?  It's a pretty trivial matter to
romp through memory 32 or 64 bits at a time.

> +EXPORT_SYMBOL(bitmap_set);
> +
> +void bitmap_clear(unsigned long *map, int start, int nr)
> +{
> +	int end = start + nr;
> +
> +	while (start < end) {
> +		__clear_bit(start, map);
> +		start++;
> +	}
> +}
> +EXPORT_SYMBOL(bitmap_clear);

Ditto.

> +unsigned long bitmap_find_next_zero_area(unsigned long *map,
> +					 unsigned long size,
> +					 unsigned long start,
> +					 unsigned int nr,
> +					 unsigned long align_mask)
> +{
> +	unsigned long index, end, i;
> +again:
> +	index = find_next_zero_bit(map, size, start);
> +
> +	/* Align allocation */
> +	index = (index + align_mask) & ~align_mask;
> +
> +	end = index + nr;
> +	if (end >= size)
> +		return end;
> +	i = find_next_bit(map, end, index);
> +	if (i < end) {
> +		start = i + 1;
> +		goto again;
> +	}
> +	return index;
> +}
> +EXPORT_SYMBOL(bitmap_find_next_zero_area);

This needs documentation, please.  It appears that `size' is the size
of the bitmap and `nr' is the number of zeroed bits we're looking for,
but an inattentive programmer could get those reversed.

Also the semantics of `align_mask' could benefit from spelling out.  Is
the alignment with respect to memory boundaries or with respect to
`map' or with respect to map+start or what?

And why does align_mask exist at all?  I was a bit surprised to see it
there.  In which scenarios will it be non-zero?

Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Akinobu Mita]

On Fri, Oct 09, 2009 at 04:41:00PM -0700, Andrew Morton wrote:
> On Fri,  9 Oct 2009 17:29:15 +0900
> Akinobu Mita <akinobu.mita@gmail.com> wrote:
> 
> > This introduces new bitmap functions:
> > 
> > bitmap_set: Set specified bit area
> > bitmap_clear: Clear specified bit area
> > bitmap_find_next_zero_area: Find free bit area
> > 
> > These are stolen from iommu helper.
> > 
> > I changed the return value of bitmap_find_next_zero_area if there is
> > no zero area.
> > 
> > find_next_zero_area in iommu helper: returns -1
> > bitmap_find_next_zero_area: return >= bitmap size
> 
> I'll plan to merge this patch into 2.6.32 so we can trickle all the
> other patches into subsystems in an orderly fashion.

Sounds good.

> > +void bitmap_set(unsigned long *map, int i, int len)
> > +{
> > +	int end = i + len;
> > +
> > +	while (i < end) {
> > +		__set_bit(i, map);
> > +		i++;
> > +	}
> > +}
> 
> This is really inefficient, isn't it?  It's a pretty trivial matter to
> romp through memory 32 or 64 bits at a time.

OK. I'll do

> > +unsigned long bitmap_find_next_zero_area(unsigned long *map,
> > +					 unsigned long size,
> > +					 unsigned long start,
> > +					 unsigned int nr,
> > +					 unsigned long align_mask)
> > +{
> > +	unsigned long index, end, i;
> > +again:
> > +	index = find_next_zero_bit(map, size, start);
> > +
> > +	/* Align allocation */
> > +	index = (index + align_mask) & ~align_mask;
> > +
> > +	end = index + nr;
> > +	if (end >= size)
> > +		return end;
> > +	i = find_next_bit(map, end, index);
> > +	if (i < end) {
> > +		start = i + 1;
> > +		goto again;
> > +	}
> > +	return index;
> > +}
> > +EXPORT_SYMBOL(bitmap_find_next_zero_area);
> 
> This needs documentation, please.  It appears that `size' is the size
> of the bitmap and `nr' is the number of zeroed bits we're looking for,
> but an inattentive programmer could get those reversed.
> 
> Also the semantics of `align_mask' could benefit from spelling out.  Is
> the alignment with respect to memory boundaries or with respect to
> `map' or with respect to map+start or what?

OK. I will document it.

And I plan to change bitmap_find_next_zero_area() to take the alignment
instead of an align_mask as Roland said.

> And why does align_mask exist at all?  I was a bit surprised to see it
> there.  In which scenarios will it be non-zero?

Because the users of iommu-helper and mlx4 need the alignment requirement
for the zero area.

arch/powerpc/kernel/iommu.c
arch/x86/kernel/amd_iommu.c
arch/x86/kernel/pci-gart_64.c
drivers/net/mlx4/alloc.c

Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Akinobu Mita]

My user space testing exposed off-by-one error find_next_zero_area
in iommu-helper. Some zero area cannot be found by this bug.

Subject: [PATCH] Fix off-by-one error in find_next_zero_area

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 lib/iommu-helper.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index 75dbda0..afc58bc 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -19,7 +19,7 @@ again:
 	index = (index + align_mask) & ~align_mask;
 
 	end = index + nr;
-	if (end >= size)
+	if (end > size)
 		return -1;
 	for (i = index; i < end; i++) {
 		if (test_bit(i, map)) {
-- 
1.5.4.3

Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Michael Ellerman]

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On Tue, 2009-10-13 at 18:10 +0900, Akinobu Mita wrote:
> My user space testing exposed off-by-one error find_next_zero_area
> in iommu-helper.

Why not merge those tests into the kernel as a configurable boot-time
self-test?

cheers

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Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Akinobu Mita]

On Wed, Oct 14, 2009 at 08:54:47AM +1100, Michael Ellerman wrote:
> On Tue, 2009-10-13 at 18:10 +0900, Akinobu Mita wrote:
> > My user space testing exposed off-by-one error find_next_zero_area
> > in iommu-helper.
> 
> Why not merge those tests into the kernel as a configurable boot-time
> self-test?

I send the test program that I used. Obviously it needs
better diagnostic messages and cleanup to be added into kernel tests.

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>

#if 1 /* Copy and paste from kernel source */

#define BITS_PER_BYTE  8
#define BITS_PER_LONG (sizeof(long) * BITS_PER_BYTE)

#define BIT_WORD(nr)	((nr) / BITS_PER_LONG)
#define BITOP_WORD(nr)	((nr) / BITS_PER_LONG)

#define BITMAP_LAST_WORD_MASK(nbits)                                    \
(                                                                       \
        ((nbits) % BITS_PER_LONG) ?                                     \
                (1UL<<((nbits) % BITS_PER_LONG))-1 : ~0UL               \
)

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))

void bitmap_set(unsigned long *map, int start, int nr)
{
	unsigned long *p = map + BIT_WORD(start);
	const int size = start + nr;
	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

	while (nr - bits_to_set >= 0) {
		*p |= mask_to_set;
		nr -= bits_to_set;
		bits_to_set = BITS_PER_LONG;
		mask_to_set = ~0UL;
		p++;
	}
	if (nr) {
		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
		*p |= mask_to_set;
	}
}

void bitmap_clear(unsigned long *map, int start, int nr)
{
	unsigned long *p = map + BIT_WORD(start);
	const int size = start + nr;
	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

	while (nr - bits_to_clear >= 0) {
		*p &= ~mask_to_clear;
		nr -= bits_to_clear;
		bits_to_clear = BITS_PER_LONG;
		mask_to_clear = ~0UL;
		p++;
	}
	if (nr) {
		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
		*p &= ~mask_to_clear;
	}
}

static unsigned long __ffs(unsigned long word)
{
	int num = 0;

	if ((word & 0xffff) == 0) {
		num += 16;
		word >>= 16;
	}
	if ((word & 0xff) == 0) {
		num += 8;
		word >>= 8;
	}
	if ((word & 0xf) == 0) {
		num += 4;
		word >>= 4;
	}
	if ((word & 0x3) == 0) {
		num += 2;
		word >>= 2;
	}
	if ((word & 0x1) == 0)
		num += 1;
	return num;
}

unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
			    unsigned long offset)
{
	const unsigned long *p = addr + BITOP_WORD(offset);
	unsigned long result = offset & ~(BITS_PER_LONG-1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset %= BITS_PER_LONG;
	if (offset) {
		tmp = *(p++);
		tmp &= (~0UL << offset);
		if (size < BITS_PER_LONG)
			goto found_first;
		if (tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}
	while (size & ~(BITS_PER_LONG-1)) {
		if ((tmp = *(p++)))
			goto found_middle;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = *p;

found_first:
	tmp &= (~0UL >> (BITS_PER_LONG - size));
	if (tmp == 0UL)		/* Are any bits set? */
		return result + size;	/* Nope. */
found_middle:
	return result + __ffs(tmp);
}

#define ffz(x)  __ffs(~(x))

unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
				 unsigned long offset)
{
	const unsigned long *p = addr + BITOP_WORD(offset);
	unsigned long result = offset & ~(BITS_PER_LONG-1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset %= BITS_PER_LONG;
	if (offset) {
		tmp = *(p++);
		tmp |= ~0UL >> (BITS_PER_LONG - offset);
		if (size < BITS_PER_LONG)
			goto found_first;
		if (~tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}
	while (size & ~(BITS_PER_LONG-1)) {
		if (~(tmp = *(p++)))
			goto found_middle;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = *p;

found_first:
	tmp |= ~0UL << size;
	if (tmp == ~0UL)	/* Are any bits zero? */
		return result + size;	/* Nope. */
found_middle:
	return result + ffz(tmp);
}

#define __ALIGN_MASK(x,mask) (((x)+(mask))&~(mask))

static inline int test_bit(int nr, const volatile unsigned long *addr)
{
	return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
}

unsigned long bitmap_find_next_zero_area(unsigned long *map,
					 unsigned long size,
					 unsigned long start,
					 unsigned int nr,
					 unsigned long align_mask)
{
	unsigned long index, end, i;
again:
	index = find_next_zero_bit(map, size, start);

	/* Align allocation */
	index = __ALIGN_MASK(index, align_mask);

	end = index + nr;
#ifdef ORIGINAL
	if (end >= size)
#else
	if (end > size)
#endif
		return end;

#ifdef ORIGINAL
	for (i = index; i < end; i++) {
		if (test_bit(i, map)) {
			start = i+1;
			goto again;
		}
	}
#else
	i = find_next_bit(map, end, index);
	if (i < end) {
		start = i + 1;
		goto again;
	}
#endif
	return index;
}

#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
#define DECLARE_BITMAP(name,bits) unsigned long name[BITS_TO_LONGS(bits)]

#endif /* Copy and paste from kernel source */

static DECLARE_BITMAP(bitmap, 1000);
static DECLARE_BITMAP(empty, 1000);
static DECLARE_BITMAP(full, 1000);

static void bitmap_dump(unsigned long *bitmap, int size)
{
	int i;

	for (i = 0; i < size; i++) {
		if (test_bit(i, bitmap))
			printf("1 ");
		else
			printf("0 ");
		if (i % 10 == 9)
			printf("\n");
	}
	printf("\n");
}

static int test1(int size)
{

	int start = random() % size;
	int nr = random() % (size - start);

	memset(bitmap, 0x00, BITS_TO_LONGS(size) * sizeof(unsigned long));

	bitmap_set(bitmap, start, nr);
	bitmap_clear(bitmap, start, nr);

	if (memcmp(empty, bitmap, BITS_TO_LONGS(size) * sizeof(unsigned long)))
		goto error;

	return 0;
error:
	bitmap_dump(bitmap, size);
	return 1;
}

int test2(int size)
{
	int start = random() % size;
	int nr = random() % (size - start);

	memset(bitmap, 0xff, BITS_TO_LONGS(size) * sizeof(unsigned long));

	bitmap_clear(bitmap, start, nr);
	bitmap_set(bitmap, start, nr);

	if (memcmp(full, bitmap, BITS_TO_LONGS(size) * sizeof(unsigned long)))
		goto error;

	return 0;
error:
	bitmap_dump(bitmap, size);
	return 1;
}

int test3(int size)
{
	int start = random() % size;
	int nr = random() % (size - start);
	unsigned long offset;

	memset(bitmap, 0x00, BITS_TO_LONGS(size) * sizeof(unsigned long));
	bitmap_set(bitmap, start, nr);
	if (start) {
		offset = bitmap_find_next_zero_area(bitmap, size, 0, start, 0);
		if (offset != 0) {
			printf("start %ld nr %ld\n", start, nr);
			printf("offset %ld != 0\n", offset);
			goto error;
		}
	}
	offset = bitmap_find_next_zero_area(bitmap, size, start,
						size - (start + nr), 0);
	if (offset != start + nr) {
		printf("start %ld nr %ld\n", start, nr);
		printf("offset %ld != size + nr %ld\n", offset, start + nr);
		goto error;
	}

	return 0;
error:
	bitmap_dump(bitmap, size);

	return 1;
}

int test4(int size)
{
	int start = random() % size;
	int nr = random() % (size - start);
	unsigned long offset;

	memset(bitmap, 0xff, BITS_TO_LONGS(size) * sizeof(unsigned long));
	bitmap_clear(bitmap, start, nr);
	offset = bitmap_find_next_zero_area(bitmap, size, start, nr, 0);
	if (nr != 0) {
		if (offset != start) {
			printf("start %ld nr %ld\n", start, nr);
			printf("offset %ld != start %ld\n", offset, start);
			goto error;
		}
	}
	return 0;
error:
	bitmap_dump(bitmap, size);

	return 1;
}

int main(int argc, char *argv[])
{
	int err = 0;

	srandom(time(NULL));

	memset(empty, 0x00, sizeof(empty));
	memset(full, 0xff, sizeof(full));

	while (!err) {
		err |= test1(1000);
		err |= test2(1000);
		err |= test3(1000);
		err |= test4(1000);
	}
	return 0;
}

[PATCH -mmotm] Fix bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area. patch

[Akinobu Mita]

Update PATCH 2/8 based on review comments by Andrew and bugfix
exposed by user space testing.

I didn't change argument of align_mask at this time because it
turned out that it needs more changes in iommu-helper users.

From: Akinobu Mita <akinobu.mita@gmail.com>
Subject: Fix bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area.patch

- Rewrite bitmap_set and bitmap_clear

  Instead of setting or clearing for each bit.

- Fix off-by-one error in bitmap_find_next_zero_area

  This bug was derived from find_next_zero_area in iommu-helper.

- Add kerneldoc for bitmap_find_next_zero_area

This patch is supposed to be folded into
bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area.patch

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 lib/bitmap.c |   60 +++++++++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 2415da4..84292c9 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -271,28 +271,62 @@ int __bitmap_weight(const unsigned long *bitmap, int bits)
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
-void bitmap_set(unsigned long *map, int i, int len)
-{
-	int end = i + len;
+#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
 
-	while (i < end) {
-		__set_bit(i, map);
-		i++;
+void bitmap_set(unsigned long *map, int start, int nr)
+{
+	unsigned long *p = map + BIT_WORD(start);
+	const int size = start + nr;
+	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
+	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
+
+	while (nr - bits_to_set >= 0) {
+		*p |= mask_to_set;
+		nr -= bits_to_set;
+		bits_to_set = BITS_PER_LONG;
+		mask_to_set = ~0UL;
+		p++;
+	}
+	if (nr) {
+		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
+		*p |= mask_to_set;
 	}
 }
 EXPORT_SYMBOL(bitmap_set);
 
 void bitmap_clear(unsigned long *map, int start, int nr)
 {
-	int end = start + nr;
-
-	while (start < end) {
-		__clear_bit(start, map);
-		start++;
+	unsigned long *p = map + BIT_WORD(start);
+	const int size = start + nr;
+	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+	while (nr - bits_to_clear >= 0) {
+		*p &= ~mask_to_clear;
+		nr -= bits_to_clear;
+		bits_to_clear = BITS_PER_LONG;
+		mask_to_clear = ~0UL;
+		p++;
+	}
+	if (nr) {
+		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+		*p &= ~mask_to_clear;
 	}
 }
 EXPORT_SYMBOL(bitmap_clear);
 
+/*
+ * bitmap_find_next_zero_area - find a contiguous aligned zero area
+ * @map: The address to base the search on
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ * @nr: The number of zeroed bits we're looking for
+ * @align_mask: Alignment mask for zero area
+ *
+ * The @align_mask should be one less than a power of 2; the effect is that
+ * the bit offset of all zero areas this function finds is multiples of that
+ * power of 2. A @align_mask of 0 means no alignment is required.
+ */
 unsigned long bitmap_find_next_zero_area(unsigned long *map,
 					 unsigned long size,
 					 unsigned long start,
@@ -304,10 +338,10 @@ again:
 	index = find_next_zero_bit(map, size, start);
 
 	/* Align allocation */
-	index = (index + align_mask) & ~align_mask;
+	index = __ALIGN_MASK(index, align_mask);
 
 	end = index + nr;
-	if (end >= size)
+	if (end > size)
 		return end;
 	i = find_next_bit(map, end, index);
 	if (i < end) {
-- 
1.5.4.3

[PATCH -mmotm -v2] Fix bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area. patch

[Akinobu Mita]

From: Akinobu Mita <akinobu.mita@gmail.com>
Subject: Fix bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area.patch

- Rewrite bitmap_set and bitmap_clear

  Instead of setting or clearing for each bit.

- Fix off-by-one errors in bitmap_find_next_zero_area

  This bug was derived from find_next_zero_area in iommu-helper.

- Add kerneldoc for bitmap_find_next_zero_area

This patch is supposed to be folded into
bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area.patch

* -v2
- Remove an extra test at the "index" value by find_next_bit

Index was just returned by find_next_zero_bit, so we know it's zero.

Noticed-by: Kyle Hubert <khubert@gmail.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 lib/bitmap.c |   62 ++++++++++++++++++++++++++++++++++++++++++++-------------
 1 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 2415da4..962b863 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -271,28 +271,62 @@ int __bitmap_weight(const unsigned long *bitmap, int bits)
 }
 EXPORT_SYMBOL(__bitmap_weight);
 
-void bitmap_set(unsigned long *map, int i, int len)
-{
-	int end = i + len;
+#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
 
-	while (i < end) {
-		__set_bit(i, map);
-		i++;
+void bitmap_set(unsigned long *map, int start, int nr)
+{
+	unsigned long *p = map + BIT_WORD(start);
+	const int size = start + nr;
+	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
+	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
+
+	while (nr - bits_to_set >= 0) {
+		*p |= mask_to_set;
+		nr -= bits_to_set;
+		bits_to_set = BITS_PER_LONG;
+		mask_to_set = ~0UL;
+		p++;
+	}
+	if (nr) {
+		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
+		*p |= mask_to_set;
 	}
 }
 EXPORT_SYMBOL(bitmap_set);
 
 void bitmap_clear(unsigned long *map, int start, int nr)
 {
-	int end = start + nr;
-
-	while (start < end) {
-		__clear_bit(start, map);
-		start++;
+	unsigned long *p = map + BIT_WORD(start);
+	const int size = start + nr;
+	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+	while (nr - bits_to_clear >= 0) {
+		*p &= ~mask_to_clear;
+		nr -= bits_to_clear;
+		bits_to_clear = BITS_PER_LONG;
+		mask_to_clear = ~0UL;
+		p++;
+	}
+	if (nr) {
+		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+		*p &= ~mask_to_clear;
 	}
 }
 EXPORT_SYMBOL(bitmap_clear);
 
+/*
+ * bitmap_find_next_zero_area - find a contiguous aligned zero area
+ * @map: The address to base the search on
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ * @nr: The number of zeroed bits we're looking for
+ * @align_mask: Alignment mask for zero area
+ *
+ * The @align_mask should be one less than a power of 2; the effect is that
+ * the bit offset of all zero areas this function finds is multiples of that
+ * power of 2. A @align_mask of 0 means no alignment is required.
+ */
 unsigned long bitmap_find_next_zero_area(unsigned long *map,
 					 unsigned long size,
 					 unsigned long start,
@@ -304,12 +338,12 @@ again:
 	index = find_next_zero_bit(map, size, start);
 
 	/* Align allocation */
-	index = (index + align_mask) & ~align_mask;
+	index = __ALIGN_MASK(index, align_mask);
 
 	end = index + nr;
-	if (end >= size)
+	if (end > size)
 		return end;
-	i = find_next_bit(map, end, index);
+	i = find_next_bit(map, end, index + 1);
 	if (i < end) {
 		start = i + 1;
 		goto again;
-- 
1.5.4.3

Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[FUJITA Tomonori]

On Tue, 13 Oct 2009 18:10:17 +0900
Akinobu Mita <akinobu.mita-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> My user space testing exposed off-by-one error find_next_zero_area
> in iommu-helper. Some zero area cannot be found by this bug.
> 
> Subject: [PATCH] Fix off-by-one error in find_next_zero_area
> 
> Signed-off-by: Akinobu Mita <akinobu.mita-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  lib/iommu-helper.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
> index 75dbda0..afc58bc 100644
> --- a/lib/iommu-helper.c
> +++ b/lib/iommu-helper.c
> @@ -19,7 +19,7 @@ again:
>  	index = (index + align_mask) & ~align_mask;
>  
>  	end = index + nr;
> -	if (end >= size)
> +	if (end > size)

I think that this is intentional; the last byte of the limit doesn't
work.
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Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Akinobu Mita]

2009/10/17 FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>:
> On Tue, 13 Oct 2009 18:10:17 +0900
> Akinobu Mita <akinobu.mita@gmail.com> wrote:
>
>> My user space testing exposed off-by-one error find_next_zero_area
>> in iommu-helper. Some zero area cannot be found by this bug.
>>
>> Subject: [PATCH] Fix off-by-one error in find_next_zero_area
>>
>> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
>> ---
>>  lib/iommu-helper.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
>> index 75dbda0..afc58bc 100644
>> --- a/lib/iommu-helper.c
>> +++ b/lib/iommu-helper.c
>> @@ -19,7 +19,7 @@ again:
>>       index = (index + align_mask) & ~align_mask;
>>
>>       end = index + nr;
>> -     if (end >= size)
>> +     if (end > size)
>
> I think that this is intentional; the last byte of the limit doesn't
> work.

It looks ok to me. Without above change, find_next_zero_area cannot
find a 64 bits zeroed area in next sample code.

        unsigned long offset;

        DECLARE_BITMAP(map, 64);

        bitmap_clear(map, 0, 64);
        offset = find_next_zero_area(map, 64, 0, 64, 0);
        if (offset >= 64)
                printf("not found\n");
        else
                printf("found\n");

Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[FUJITA Tomonori]

On Sat, 17 Oct 2009 23:43:56 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:

> 2009/10/17 FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>:
> > On Tue, 13 Oct 2009 18:10:17 +0900
> > Akinobu Mita <akinobu.mita@gmail.com> wrote:
> >
> >> My user space testing exposed off-by-one error find_next_zero_area
> >> in iommu-helper. Some zero area cannot be found by this bug.
> >>
> >> Subject: [PATCH] Fix off-by-one error in find_next_zero_area
> >>
> >> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> >> ---
> >>  lib/iommu-helper.c |    2 +-
> >>  1 files changed, 1 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
> >> index 75dbda0..afc58bc 100644
> >> --- a/lib/iommu-helper.c
> >> +++ b/lib/iommu-helper.c
> >> @@ -19,7 +19,7 @@ again:
> >>       index = (index + align_mask) & ~align_mask;
> >>
> >>       end = index + nr;
> >> -     if (end >= size)
> >> +     if (end > size)
> >
> > I think that this is intentional; the last byte of the limit doesn't
> > work.
> 
> It looks ok to me. Without above change, find_next_zero_area cannot
> find a 64 bits zeroed area in next sample code.

I meant that we don't want to find such area for IOMMUs (IIRC, it code
came from POWER IOMMU).


>         unsigned long offset;
> 
>         DECLARE_BITMAP(map, 64);
> 
>         bitmap_clear(map, 0, 64);
>         offset = find_next_zero_area(map, 64, 0, 64, 0);
>         if (offset >= 64)
>                 printf("not found\n");
>         else
>                 printf("found\n");
> --
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Re: [PATCH 2/8] bitmap: Introduce bitmap_set, bitmap_clear, bitmap_find_next_zero_area

[Akinobu Mita]

>> >> --- a/lib/iommu-helper.c
>> >> +++ b/lib/iommu-helper.c
>> >> @@ -19,7 +19,7 @@ again:
>> >>       index = (index + align_mask) & ~align_mask;
>> >>
>> >>       end = index + nr;
>> >> -     if (end >= size)
>> >> +     if (end > size)
>> >
>> > I think that this is intentional; the last byte of the limit doesn't
>> > work.
>>
>> It looks ok to me. Without above change, find_next_zero_area cannot
>> find a 64 bits zeroed area in next sample code.
>
> I meant that we don't want to find such area for IOMMUs (IIRC, it code
> came from POWER IOMMU).

OK, I see.  I think we need the comment about it.

So we cannot replace find_next_zero_area by bitmap_find_next_zero_area
and current -mmotm has the bug introduced by this patch in iommu-helper
and I also introduced the bug in bitmap_find_next_zero_area if
align_mask != 0 in
bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area-fix.patch

Andrew, please drop

lib-iommu-helperc-fix-off-by-one-error-in-find_next_zero_area.patch
iommu-helper-simplify-find_next_zero_area.patch
bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area.patch
bitmap-introduce-bitmap_set-bitmap_clear-bitmap_find_next_zero_area-fix.patch
iommu-helper-use-bitmap-library.patch
isp1362-hcd-use-bitmap_find_next_zero_area.patch
mlx4-use-bitmap_find_next_zero_area.patch
sparc-use-bitmap_find_next_zero_area.patch
ia64-use-bitmap_find_next_zero_area.patch
genalloc-use-bitmap_find_next_zero_area.patch

I'll overhaul the patchset and retry again.