On Thu, 27 Nov 2014 22:07:36 +0200
"Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
> Add low level APIs to test/set/clear feature bits.
> For use by transports, to make it easier to
> write code independent of feature bit array format.
>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> include/linux/virtio_config.h | 53 ++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 50 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 7f4ef66..249fcd6 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -77,11 +77,47 @@ void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
> unsigned int fbit);
>
> /**
> - * virtio_has_feature - helper to determine if this device has this feature.
> + * __virtio_test_bit - helper to test feature bits. For use by transports.
> + * Devices should normally use virtio_has_feature,
> + * which includes more checks.
> * @vdev: the device
> * @fbit: the feature bit
> */
> -static inline bool virtio_has_feature(const struct virtio_device *vdev,
> +static inline bool __virtio_test_bit(const struct virtio_device *vdev,
> + unsigned int fbit)
> +{
> + /* Did you forget to fix assumptions on max features? */
> + if (__builtin_constant_p(fbit))
> + BUILD_BUG_ON(fbit >= 32);
> + else
> + BUG_ON(fbit >= 32);
Does this want to be a helper? Might be overkill, but I'm always wary
of changes that need to be applied manually in many different places :)
> +
> + return test_bit(fbit, vdev->features);
> +}
> +
> +/**
> + * __virtio_set_bit - helper to set feature bits. For use by transports.
> + * @vdev: the device
> + * @fbit: the feature bit
> + */
> +static inline void __virtio_set_bit(struct virtio_device *vdev,
> + unsigned int fbit)
> +{
> + /* Did you forget to fix assumptions on max features? */
> + if (__builtin_constant_p(fbit))
> + BUILD_BUG_ON(fbit >= 32);
> + else
> + BUG_ON(fbit >= 32);
> +
> + set_bit(fbit, vdev->features);
> +}
> +
> +/**
> + * __virtio_clear_bit - helper to set feature bits. For use by transports.
s/set/clear/
> + * @vdev: the device
> + * @fbit: the feature bit
> + */
> +static inline void __virtio_clear_bit(struct virtio_device *vdev,
> unsigned int fbit)
> {
> /* Did you forget to fix assumptions on max features? */
> @@ -90,10 +126,21 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev,
> else
> BUG_ON(fbit >= 32);
>
> + clear_bit(fbit, vdev->features);
> +}
> +
> +/**
> + * virtio_has_feature - helper to determine if this device has this feature.
> + * @vdev: the device
> + * @fbit: the feature bit
> + */
> +static inline bool virtio_has_feature(const struct virtio_device *vdev,
> + unsigned int fbit)
> +{
> if (fbit < VIRTIO_TRANSPORT_F_START)
> virtio_check_driver_offered_feature(vdev, fbit);
>
> - return test_bit(fbit, vdev->features);
> + return __virtio_test_bit(vdev, fbit);
> }
>
> static inline
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