1 files changed, 15 insertions, 22 deletions

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index acf5e8df3504..f58e97446abc 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -28,8 +28,8 @@
  * The available bitmap operations and their rough meaning in the
  * case that the bitmap is a single unsigned long are thus:
  *
- * Note that nbits should be always a compile time evaluable constant.
- * Otherwise many inlines will generate horrible code.
+ * The generated code is more efficient when nbits is known at
+ * compile-time and at most BITS_PER_LONG.
  *
  * ::
  *
@@ -204,38 +204,31 @@ extern int bitmap_print_to_pagebuf(bool list, char *buf,
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
 #define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
 
+/*
+ * The static inlines below do not handle constant nbits==0 correctly,
+ * so make such users (should any ever turn up) call the out-of-line
+ * versions.
+ */
 #define small_const_nbits(nbits) \
-	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG)
+	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
 
 static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
-		*dst = 0UL;
-	else {
-		unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
-		memset(dst, 0, len);
-	}
+	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+	memset(dst, 0, len);
 }
 
 static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
-		*dst = ~0UL;
-	else {
-		unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
-		memset(dst, 0xff, len);
-	}
+	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+	memset(dst, 0xff, len);
 }
 
 static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
 			unsigned int nbits)
 {
-	if (small_const_nbits(nbits))
-		*dst = *src;
-	else {
-		unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
-		memcpy(dst, src, len);
-	}
+	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
+	memcpy(dst, src, len);
 }
 
 /*
@@ -398,7 +391,7 @@ static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
 }
 
 static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src,
-				unsigned int shift, int nbits)
+				unsigned int shift, unsigned int nbits)
 {
 	if (small_const_nbits(nbits))
 		*dst = (*src & BITMAP_LAST_WORD_MASK(nbits)) >> shift;