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.m...@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.m...@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
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