Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933060AbcKVRZx (ORCPT ); Tue, 22 Nov 2016 12:25:53 -0500 Received: from mail-vk0-f47.google.com ([209.85.213.47]:34655 "EHLO mail-vk0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932642AbcKVRZv (ORCPT ); Tue, 22 Nov 2016 12:25:51 -0500 MIME-Version: 1.0 In-Reply-To: <63a3cd15-76a9-8286-fa26-ebb9029427aa@redhat.com> References: <1479793910-120188-1-git-send-email-arei.gonglei@huawei.com> <1479793910-120188-3-git-send-email-arei.gonglei@huawei.com> <20161122170346-mutt-send-email-mst@kernel.org> <63a3cd15-76a9-8286-fa26-ebb9029427aa@redhat.com> From: Andy Lutomirski Date: Tue, 22 Nov 2016 09:25:29 -0800 Message-ID: Subject: Re: [PATCH 2/2] virtio_ring: fix complaint by sparse To: Thomas Huth Cc: "Michael S. Tsirkin" , Gonglei , david@gibson.dropbear.id.au, "linux-kernel@vger.kernel.org" , Linux Virtualization , Andy Lutomirski Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2597 Lines: 58 On Tue, Nov 22, 2016 at 7:16 AM, Thomas Huth wrote: > On 22.11.2016 16:04, Michael S. Tsirkin wrote: >> On Tue, Nov 22, 2016 at 01:51:50PM +0800, Gonglei wrote: >>> # make C=2 CF="-D__CHECK_ENDIAN__" ./drivers/virtio/ >>> >>> drivers/virtio/virtio_ring.c:423:19: warning: incorrect type in assignment (different base types) >>> drivers/virtio/virtio_ring.c:423:19: expected unsigned int [unsigned] [assigned] i >>> drivers/virtio/virtio_ring.c:423:19: got restricted __virtio16 [usertype] next >>> drivers/virtio/virtio_ring.c:423:19: warning: incorrect type in assignment (different base types) >>> drivers/virtio/virtio_ring.c:423:19: expected unsigned int [unsigned] [assigned] i >>> drivers/virtio/virtio_ring.c:423:19: got restricted __virtio16 [usertype] next >>> drivers/virtio/virtio_ring.c:423:19: warning: incorrect type in assignment (different base types) >>> drivers/virtio/virtio_ring.c:423:19: expected unsigned int [unsigned] [assigned] i >>> drivers/virtio/virtio_ring.c:423:19: got restricted __virtio16 [usertype] next >>> drivers/virtio/virtio_ring.c:604:39: warning: incorrect type in initializer (different base types) >>> drivers/virtio/virtio_ring.c:604:39: expected unsigned short [unsigned] [usertype] nextflag >>> drivers/virtio/virtio_ring.c:604:39: got restricted __virtio16 >>> drivers/virtio/virtio_ring.c:612:33: warning: restricted __virtio16 degrades to integer >>> >>> Signed-off-by: Gonglei >>> --- >>> drivers/virtio/virtio_ring.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c >>> index 489bfc6..d2863c3 100644 >>> --- a/drivers/virtio/virtio_ring.c >>> +++ b/drivers/virtio/virtio_ring.c >>> @@ -420,7 +420,7 @@ static inline int virtqueue_add(struct virtqueue *_vq, >>> if (i == err_idx) >>> break; >>> vring_unmap_one(vq, &desc[i]); >>> - i = vq->vring.desc[i].next; >>> + i = virtio16_to_cpu(_vq->vdev, vq->vring.desc[i].next); >>> } >>> >>> vq->vq.num_free += total_sg; > [...] >> Wow are you saying endian-ness is all wrong for the next field? >> How do things ever work then? > > The above code is only in the error cleanup path (after the > "unmap_release" label, introduced by commit 780bc7903), so it likely has > never been exercised in the field. > I think Gonlei's patch is right, there should be a virtio16_to_cpu() here. Agreed. > > Thomas > > -- Andy Lutomirski AMA Capital Management, LLC