2 files changed, 105 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 3b89c64bcfd8..d7dd83fafeba 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -248,6 +248,25 @@ static inline unsigned long __ffs64(u64 word)
 }
 
 /**
+ * fns - find N'th set bit in a word
+ * @word: The word to search
+ * @n: Bit to find
+ */
+static inline unsigned long fns(unsigned long word, unsigned int n)
+{
+	unsigned int bit;
+
+	while (word) {
+		bit = __ffs(word);
+		if (n-- == 0)
+			return bit;
+		__clear_bit(bit, &word);
+	}
+
+	return BITS_PER_LONG;
+}
+
+/**
  * assign_bit - Assign value to a bit in memory
  * @nr: the bit to set
  * @addr: the address to start counting from
diff --git a/include/linux/find.h b/include/linux/find.h
index dead6f53a97b..b100944daba0 100644
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -15,6 +15,11 @@ unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long
 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);
+unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n);
+unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2,
+				unsigned long size, unsigned long n);
+unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
+					unsigned long size, unsigned long n);
 extern unsigned long _find_first_and_bit(const unsigned long *addr1,
 					 const unsigned long *addr2, unsigned long size);
 extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
@@ -136,6 +141,87 @@ unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
 }
 #endif
 
+/**
+ * find_nth_bit - find N'th set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The maximum number of bits to search
+ * @n: The number of set bit, which position is needed, counting from 0
+ *
+ * The following is semantically equivalent:
+ *	 idx = find_nth_bit(addr, size, 0);
+ *	 idx = find_first_bit(addr, size);
+ *
+ * Returns the bit number of the N'th set bit.
+ * If no such, returns @size.
+ */
+static inline
+unsigned long find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
+{
+	if (n >= size)
+		return size;
+
+	if (small_const_nbits(size)) {
+		unsigned long val =  *addr & GENMASK(size - 1, 0);
+
+		return val ? fns(val, n) : size;
+	}
+
+	return __find_nth_bit(addr, size, n);
+}
+
+/**
+ * find_nth_and_bit - find N'th set bit in 2 memory regions
+ * @addr1: The 1st address to start the search at
+ * @addr2: The 2nd address to start the search at
+ * @size: The maximum number of bits to search
+ * @n: The number of set bit, which position is needed, counting from 0
+ *
+ * Returns the bit number of the N'th set bit.
+ * If no such, returns @size.
+ */
+static inline
+unsigned long find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2,
+				unsigned long size, unsigned long n)
+{
+	if (n >= size)
+		return size;
+
+	if (small_const_nbits(size)) {
+		unsigned long val =  *addr1 & *addr2 & GENMASK(size - 1, 0);
+
+		return val ? fns(val, n) : size;
+	}
+
+	return __find_nth_and_bit(addr1, addr2, size, n);
+}
+
+/**
+ * find_nth_andnot_bit - find N'th set bit in 2 memory regions,
+ *			 flipping bits in 2nd region
+ * @addr1: The 1st address to start the search at
+ * @addr2: The 2nd address to start the search at
+ * @size: The maximum number of bits to search
+ * @n: The number of set bit, which position is needed, counting from 0
+ *
+ * Returns the bit number of the N'th set bit.
+ * If no such, returns @size.
+ */
+static inline
+unsigned long find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
+				unsigned long size, unsigned long n)
+{
+	if (n >= size)
+		return size;
+
+	if (small_const_nbits(size)) {
+		unsigned long val =  *addr1 & (~*addr2) & GENMASK(size - 1, 0);
+
+		return val ? fns(val, n) : size;
+	}
+
+	return __find_nth_andnot_bit(addr1, addr2, size, n);
+}
+
 #ifndef find_first_and_bit
 /**
  * find_first_and_bit - find the first set bit in both memory regions