[libvirt] [PATCH 6/6] util: bitmap: Note that shrinking the bitmap requires clearing of unused bits

Peter Krempa pkrempa at redhat.com
Mon Feb 5 13:17:47 UTC 2018


Note the fact that the unused portion of the last element in the bitmap
needs to be cleared, since we use functions which process only full-size
elements and don't really deal with individual bits.
---
 src/util/virbitmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index 82b1f76427..0cc5292d8c 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -45,6 +45,10 @@ struct _virBitmap {
     size_t nbits;
     size_t map_len;
     size_t map_alloc;
+
+    /* Note that code below depends on the fact that unused bits of the bitmap
+     * are not set. Any function decreasing the size of the map needs clear
+     * bits which don't belong to the bitmap any more. */
     unsigned long *map;
 };

-- 
2.15.0




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