In preparation of introducing for_each_cpu_andnot(), add a variant of
find_next_bit() that negate the bits in @addr2 when ANDing them with the
bits in @addr1.
Signed-off-by: Valentin Schneider <vschneid@xxxxxxxxxx>
---
include/linux/find.h | 33 +++++++++++++++++++++++++++++++++
lib/find_bit.c | 9 +++++++++
2 files changed, 42 insertions(+)
diff --git a/include/linux/find.h b/include/linux/find.h
index dead6f53a97b..e60b1ce89b29 100644
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -12,6 +12,8 @@ unsigned long _find_next_bit(const unsigned long *addr1, unsigned long nbits,
unsigned long start);
unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
unsigned long nbits, unsigned long start);
+unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
+ unsigned long nbits, unsigned long start);
unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
unsigned long start);
extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size);
@@ -86,6 +88,37 @@ unsigned long find_next_and_bit(const unsigned long *addr1,
}
#endif
+#ifndef find_next_andnot_bit
+/**
+ * find_next_andnot_bit - find the next set bit in *addr1 excluding all the bits
+ * in *addr2
+ * @addr1: The first address to base the search on
+ * @addr2: The second address to base the search on
+ * @size: The bitmap size in bits
+ * @offset: The bitnumber to start searching at
+ *
+ * Returns the bit number for the next set bit
+ * If no bits are set, returns @size.
+ */
+static inline
+unsigned long find_next_andnot_bit(const unsigned long *addr1,
+ const unsigned long *addr2, unsigned long size,
+ unsigned long offset)
+{
+ if (small_const_nbits(size)) {
+ unsigned long val;
+
+ if (unlikely(offset >= size))
+ return size;
+
+ val = *addr1 & ~*addr2 & GENMASK(size - 1, offset);
+ return val ? __ffs(val) : size;
+ }
+
+ return _find_next_andnot_bit(addr1, addr2, size, offset);
+}
+#endif
+
#ifndef find_next_zero_bit
/**
* find_next_zero_bit - find the next cleared bit in a memory region
diff --git a/lib/find_bit.c b/lib/find_bit.c
index d00ee23ab657..53b02405421b 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -120,6 +120,15 @@ unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long
EXPORT_SYMBOL(_find_next_and_bit);
#endif
+#ifndef find_next_andnot_bit
+unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
+ unsigned long nbits, unsigned long start)
+{
+ return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_andnot_bit);
+#endif
+
#ifndef find_next_zero_bit
unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
unsigned long start)
--
2.31.1
