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 <tiwei.bie at intel.com> > --- > @@ -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?> -- > 2.17.1
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 <tiwei.bie at intel.com> > > --- > > @@ -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
On Sat, Dec 08, 2018 at 09:47:29PM +0800, Tiwei Bie wrote:> 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 <tiwei.bie at intel.com> > > > --- > > > @@ -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?What I'd like to see is a macro that warns/errors out if the shift is too large. I'll think it over on the weekend.> > > > > > -- > > > 2.17.1