Fix: power of 2 size check should apply to size_t type, not uint32_t

Fix this by using the much simpler x & (x - 1) check (rather than
hweight(x) == 1).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/libringbuffer/backend_internal.h b/libringbuffer/backend_internal.h
index 36d53dfd531357037501a539cd8c991c9d2ca4d9..c4fb7604aa18bf9b3018551257dd3be61285b022 100644 (file)
--- a/libringbuffer/backend_internal.h
+++ b/libringbuffer/backend_internal.h
@@ -475,20 +475,4 @@ static inline int get_count_order(unsigned int count)
        return order;
 }
 
-static inline
-unsigned int hweight32(unsigned int value)
-{
-       unsigned int r;
-
-       r = value;
-       r = r - ((r >> 1) & 0x55555555);
-       r = (r & 0x33333333) + ((r >> 2) & 0x33333333);
-       r += r >> 4;
-       r &= 0x0F0F0F0F;
-       r += r >> 8;
-       r += r >> 16;
-       r &= 0x000000FF;
-       return r;
-}
-
 #endif /* _LINUX_RING_BUFFER_BACKEND_INTERNAL_H */

diff --git a/libringbuffer/ring_buffer_backend.c b/libringbuffer/ring_buffer_backend.c
index 769e24bffa0c35475aee4ddcec62b60b4b618d93..e949a5e292d2048f306760f329f64d668a0c30cd 100644 (file)
--- a/libringbuffer/ring_buffer_backend.c
+++ b/libringbuffer/ring_buffer_backend.c
@@ -218,11 +218,12 @@ int channel_backend_init(struct channel_backend *chanb,
                return -EINVAL;
 
        /*
-        * Make sure the number of subbuffers and subbuffer size are power of 2.
+        * Make sure the number of subbuffers and subbuffer size are
+        * power of 2, and nonzero.
         */
-       if (hweight32(subbuf_size) != 1)
+       if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
                return -EINVAL;
-       if (hweight32(num_subbuf) != 1)
+       if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
                return -EINVAL;
 
        ret = subbuffer_id_check_index(config, num_subbuf);