From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tiwei Bie Subject: Re: [RFC 3/3] virtio_ring: use new vring flags Date: Sat, 8 Dec 2018 21:47:29 +0800 Message-ID: <20181208134728.GC29772@dpdk-tbie> References: <20181207084842.13133-1-tiwei.bie@intel.com> <20181207084842.13133-4-tiwei.bie@intel.com> <20181207130822-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: virtio-dev@lists.oasis-open.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, maxime.coquelin@redhat.com, wexu@redhat.com To: "Michael S. Tsirkin" Return-path: Content-Disposition: inline In-Reply-To: <20181207130822-mutt-send-email-mst@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Fri, Dec 07, 2018 at 01:10:48PM -0500, Michael S. Tsirkin wrote: > On Fri, Dec 07, 2018 at 04:48:42PM +0800, Tiwei Bie wrote: > > Switch to using the _SPLIT_ and _PACKED_ variants of vring flags > > in split ring and packed ring respectively. > > > > Signed-off-by: Tiwei Bie > > --- > > @@ -502,7 +505,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > > } > > } > > /* Last one doesn't continue. */ > > - desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT); > > + desc[prev].flags &= cpu_to_virtio16(_vq->vdev, > > + (u16)~BIT(VRING_SPLIT_DESC_F_NEXT)); > > > > if (indirect) { > > /* Now that the indirect table is filled in, map it. */ > > I kind of dislike it that this forces use of a cast here. > Kind of makes it more fragile. Let's use a temporary instead? I tried something like this: u16 mask = ~BIT(VRING_SPLIT_DESC_F_NEXT); And it will still cause the warning: warning: large integer implicitly truncated to unsigned type [-Woverflow] u16 mask = ~BIT(VRING_SPLIT_DESC_F_NEXT); If the cast isn't wanted, maybe use ~(1 << VRING_SPLIT_DESC_F_NEXT) directly? > > > -- > > 2.17.1