[PATCH v6 01/46] virtio: add low-level APIs for feature bits
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2014-11-27 20:07:58
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Subsystem:
the rest, virtio core · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
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@redhat.com> --- 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); + + 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. + * @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
--
MST