[PATCH 2/4] virtio: Fix Clang warning (bugprone-sizeof-expression, cert-arr39-c)

In `virtqueue_read_indirect_desc()`, the pointer arithmetic involving `desc` is intentional. We add the length in bytes (`read_len`) divided by the size of `struct vring_desc` to `desc`, which is an array of `struct vring_desc`. This correctly calculates the offset in terms of the number of `struct vring_desc` elements. Clang issues the following warning due to this explicit scaling: virtio.c:238:8: error: suspicious usage of 'sizeof(...)' in pointer arithmetic; this scaled value will be scaled again by the '+=' operator [bugprone-sizeof-expression,cert-arr39-c,-Werror] 238 | desc += read_len / sizeof(struct vring_desc); | ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ virtio.c:238:8: note: '+=' in pointer arithmetic internally scales with 'sizeof(struct vring_desc)' == 16 This behavior is intended, so the warning can be considered a false positive in this context. The code correctly advances the pointer by the desired number of descriptor entries. Signed-off-by: Laurent Vivier --- virtio.c | 1 + 1 file changed, 1 insertion(+) diff --git a/virtio.c b/virtio.c index bc2b89a7f4a7..f7db0073b66c 100644 --- a/virtio.c +++ b/virtio.c @@ -235,6 +235,7 @@ static int virtqueue_read_indirect_desc(const struct vu_dev *dev, memcpy(desc, orig_desc, read_len); len -= read_len; addr += read_len; + /* NOLINTNEXTLINE(bugprone-sizeof-expression,cert-arr39-c) */ desc += read_len / sizeof(struct vring_desc); } -- 2.49.0