[Qemu-devel] [PATCH v2] bitmap: fix BITMAP_LAST_WORD_MASK

[Wei Wang <wei.w.wang@intel.com>]

When "nbits = 0", which means no bits to mask, this macro is expected to
return 0, instead of 0xffffffff. This patch changes the macro to return
0 when there is no bit needs to be masked.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
CC: Juan Quintela <quintela@redhat.com>
CC: Dr. David Alan Gilbert <dgilbert@redhat.com>
CC: Peter Xu <peterx@redhat.com>
---
 include/qemu/bitmap.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

v1->v2 ChangeLog:
- fix the macro directly, instead of fixing the callers one by one.

diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
index 509eedd..9372423 100644
--- a/include/qemu/bitmap.h
+++ b/include/qemu/bitmap.h
@@ -60,7 +60,10 @@
  */
 
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
-#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))
+#define BITMAP_LAST_WORD_MASK(nbits)                       \
+(                                                          \
+    nbits ? (~0UL >> (-(nbits) & (BITS_PER_LONG - 1))) : 0 \
+)
 
 #define DECLARE_BITMAP(name,bits)                  \
         unsigned long name[BITS_TO_LONGS(bits)]
-- 
2.7.4