bitops.h: Improve find_xxx_bit() documentation

Document the following functions return the bitmap size
if no matching bit is found:

- find_first_bit
- find_next_bit
- find_last_bit
- find_first_zero_bit
- find_next_zero_bit

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20210510200758.2623154-2-philmd@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

include/qemu/bitops.h

@@ -140,7 +140,8 @@ static inline int test_bit(long nr, const unsigned long *addr)
  * @addr: The address to start the search at
  * @size: The maximum size to search
  *
- * Returns the bit number of the first set bit, or size.
+ * Returns the bit number of the last set bit,
+ * or @size if there is no set bit in the bitmap.
  */
 unsigned long find_last_bit(const unsigned long *addr,
                             unsigned long size);
@@ -150,6 +151,9 @@ unsigned long find_last_bit(const unsigned long *addr,
  * @addr: The address to base the search on
  * @offset: The bitnumber to start searching at
  * @size: The bitmap size in bits
+ *
+ * Returns the bit number of the next set bit,
+ * or @size if there are no further set bits in the bitmap.
  */
 unsigned long find_next_bit(const unsigned long *addr,
                             unsigned long size,
@@ -160,6 +164,9 @@ unsigned long find_next_bit(const unsigned long *addr,
  * @addr: The address to base the search on
  * @offset: The bitnumber to start searching at
  * @size: The bitmap size in bits
+ *
+ * Returns the bit number of the next cleared bit,
+ * or @size if there are no further clear bits in the bitmap.
  */
 
 unsigned long find_next_zero_bit(const unsigned long *addr,
@@ -171,7 +178,8 @@ unsigned long find_next_zero_bit(const unsigned long *addr,
  * @addr: The address to start the search at
  * @size: The maximum size to search
  *
- * Returns the bit number of the first set bit.
+ * Returns the bit number of the first set bit,
+ * or @size if there is no set bit in the bitmap.
  */
 static inline unsigned long find_first_bit(const unsigned long *addr,
                                            unsigned long size)
@@ -194,7 +202,8 @@ static inline unsigned long find_first_bit(const unsigned long *addr,
  * @addr: The address to start the search at
  * @size: The maximum size to search
  *
- * Returns the bit number of the first cleared bit.
+ * Returns the bit number of the first cleared bit,
+ * or @size if there is no clear bit in the bitmap.
  */
 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
                                                 unsigned long size)