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Subject[PATCH 5/7] lib/bitmap: introduce for_each_set_bit_wrap() macro
Date
Add for_each_set_bit_wrap() macro and use it in for_each_cpu_wrap(). The
new macro is based on __for_each_wrap() iterator, which is simpler and
smaller than cpumask_next_wrap().

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
include/linux/cpumask.h | 6 ++----
include/linux/find.h | 39 +++++++++++++++++++++++++++++++++++++++
2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 3a9566f1373a..286804bfe3b7 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -286,10 +286,8 @@ unsigned int __pure cpumask_next_wrap(int n, const struct cpumask *mask, int sta
*
* After the loop, cpu is >= nr_cpu_ids.
*/
-#define for_each_cpu_wrap(cpu, mask, start) \
- for ((cpu) = cpumask_next_wrap((start)-1, (mask), (start), false); \
- (cpu) < nr_cpumask_bits; \
- (cpu) = cpumask_next_wrap((cpu), (mask), (start), true))
+#define for_each_cpu_wrap(cpu, mask, start) \
+ for_each_set_bit_wrap(cpu, cpumask_bits(mask), nr_cpumask_bits, start)

/**
* for_each_cpu_and - iterate over every cpu in both masks
diff --git a/include/linux/find.h b/include/linux/find.h
index 77c087b7a451..3b746a183216 100644
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -336,6 +336,32 @@ unsigned long find_next_bit_wrap(const unsigned long *addr,
return bit < offset ? bit : size;
}

+/*
+ * Helper for for_each_set_bit_wrap(). Make sure you're doing right thing
+ * before using it alone.
+ */
+static inline
+unsigned long __for_each_wrap(const unsigned long *bitmap, unsigned long size,
+ unsigned long start, unsigned long n)
+{
+ unsigned long bit;
+
+ /* If not wrapped around */
+ if (n > start) {
+ /* and have a bit, just return it. */
+ bit = find_next_bit(bitmap, size, n);
+ if (bit < size)
+ return bit;
+
+ /* Otherwise, wrap around and ... */
+ n = 0;
+ }
+
+ /* Search the other part. */
+ bit = find_next_bit(bitmap, start, n);
+ return bit < start ? bit : size;
+}
+
/**
* find_next_clump8 - find next 8-bit clump with set bits in a memory region
* @clump: location to store copy of found clump
@@ -514,6 +540,19 @@ unsigned long find_next_bit_le(const void *addr, unsigned
(b) = find_next_zero_bit((addr), (size), (e) + 1), \
(e) = find_next_bit((addr), (size), (b) + 1))

+/**
+ * for_each_set_bit_wrap - iterate over all set bits starting from @start, and
+ * wrapping around the end of bitmap.
+ * @bit: offset for current iteration
+ * @addr: bitmap address to base the search on
+ * @size: bitmap size in number of bits
+ * @start: Starting bit for bitmap traversing, wrapping around the bitmap end
+ */
+#define for_each_set_bit_wrap(bit, addr, size, start) \
+ for ((bit) = find_next_bit_wrap((addr), (size), (start)); \
+ (bit) < (size); \
+ (bit) = __for_each_wrap((addr), (size), (start), (bit) + 1))
+
/**
* for_each_set_clump8 - iterate over bitmap for each 8-bit clump with set bits
* @start: bit offset to start search and to store the current iteration offset
--
2.34.1
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