The old documentation is left over from when we used a structure with strategy pointers.
Signed-off-by: Rusty Russell <[email protected]> --- include/linux/virtio.h | 130 ++++++++++++++++++++++++++++++++----------------- 1 file changed, 87 insertions(+), 43 deletions(-) diff --git a/include/linux/virtio.h b/include/linux/virtio.h --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -26,52 +26,22 @@ struct virtqueue { }; /** - * operations for virtqueue - * virtqueue_add_buf: expose buffer to other end - * vq: the struct virtqueue we're talking about. - * sg: the description of the buffer(s). - * out_num: the number of sg readable by other side - * in_num: the number of sg which are writable (after readable ones) - * data: the token identifying the buffer. - * gfp: how to do memory allocations (if necessary). - * Returns remaining capacity of queue (sg segments) or a negative error. - * virtqueue_kick: update after add_buf - * vq: the struct virtqueue - * After one or more add_buf calls, invoke this to kick the other side. - * virtqueue_get_buf: get the next used buffer - * vq: the struct virtqueue we're talking about. - * len: the length written into the buffer - * Returns NULL or the "data" token handed to add_buf. - * virtqueue_disable_cb: disable callbacks - * vq: the struct virtqueue we're talking about. - * Note that this is not necessarily synchronous, hence unreliable and only - * useful as an optimization. - * virtqueue_enable_cb: restart callbacks after disable_cb. - * vq: the struct virtqueue we're talking about. - * This re-enables callbacks; it returns "false" if there are pending - * buffers in the queue, to detect a possible race between the driver - * checking for more work, and enabling callbacks. - * virtqueue_enable_cb_delayed: restart callbacks after disable_cb. - * vq: the struct virtqueue we're talking about. - * This re-enables callbacks but hints to the other side to delay - * interrupts until most of the available buffers have been processed; - * it returns "false" if there are many pending buffers in the queue, - * to detect a possible race between the driver checking for more work, - * and enabling callbacks. - * virtqueue_detach_unused_buf: detach first unused buffer - * vq: the struct virtqueue we're talking about. - * Returns NULL or the "data" token handed to add_buf - * virtqueue_get_vring_size: return the size of the virtqueue's vring - * vq: the struct virtqueue containing the vring of interest. - * Returns the size of the vring. + * virtqueue_add_buf_gfp - expose buffer to other end + * @vq: the struct virtqueue we're talking about. + * @sg: the description of the buffer(s). + * @out_num: the number of sg readable by other side + * @in_num: the number of sg which are writable (after readable ones) + * @data: the token identifying the buffer. + * @gfp: how to do memory allocations (if necessary). * - * Locking rules are straightforward: the driver is responsible for - * locking. No two operations may be invoked simultaneously, with the exception - * of virtqueue_disable_cb. + * Caller must ensure we don't call this with other virtqueue operations + * at the same time (except where noted). * - * All operations can be called in any context. + * Returns remaining capacity of queue or a negative error + * (ie. ENOSPC). Note that it only really makes sense to treat all + * positive return values as "available": indirect buffers mean that + * we can put an entire sg[] array inside a single queue entry. */ - int virtqueue_add_buf_gfp(struct virtqueue *vq, struct scatterlist sg[], unsigned int out_num, @@ -88,18 +58,92 @@ static inline int virtqueue_add_buf(stru return virtqueue_add_buf_gfp(vq, sg, out_num, in_num, data, GFP_ATOMIC); } +/** + * virtqueue_kick - update after add_buf + * @vq: the struct virtqueue + * + * After one or more virtqueue_add_buf_gfp calls, invoke this to kick + * the other side. + * + * Caller must ensure we don't call this with other virtqueue + * operations at the same time (except where noted). + */ void virtqueue_kick(struct virtqueue *vq); +/** + * virtqueue_get_buf - get the next used buffer + * @vq: the struct virtqueue we're talking about. + * @len: the length written into the buffer + * + * If the driver wrote data into the buffer, @len will be set to the + * amount written. This means you don't need to clear the buffer + * beforehand to ensure there's no data leakage in the case of short + * writes. + * + * Caller must ensure we don't call this with other virtqueue + * operations at the same time (except where noted). + * + * Returns NULL if there are no used buffers, or the "data" token + * handed to virtqueue_add_buf_gfp(). + */ void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len); +/** + * virtqueue_disable_cb - disable callbacks + * @vq: the struct virtqueue we're talking about. + * + * Note that this is not necessarily synchronous, hence unreliable and only + * useful as an optimization. + * + * Unlike other operations, this need not be serialized. + */ void virtqueue_disable_cb(struct virtqueue *vq); +/** + * virtqueue_enable_cb - restart callbacks after disable_cb. + * @vq: the struct virtqueue we're talking about. + * + * This re-enables callbacks; it returns "false" if there are pending + * buffers in the queue, to detect a possible race between the driver + * checking for more work, and enabling callbacks. + * + * Caller must ensure we don't call this with other virtqueue + * operations at the same time (except where noted). + */ bool virtqueue_enable_cb(struct virtqueue *vq); +/** + * virtqueue_enable_cb_delayed - restart callbacks after disable_cb. + * @vq: the struct virtqueue we're talking about. + * + * This re-enables callbacks but hints to the other side to delay + * interrupts until most of the available buffers have been processed; + * it returns "false" if there are many pending buffers in the queue, + * to detect a possible race between the driver checking for more work, + * and enabling callbacks. + * + * Caller must ensure we don't call this with other virtqueue + * operations at the same time (except where noted). + */ bool virtqueue_enable_cb_delayed(struct virtqueue *vq); +/** + * virtqueue_detach_unused_buf - detach first unused buffer + * @vq: the struct virtqueue we're talking about. + * + * Returns NULL or the "data" token handed to virtqueue_add_buf_gfp(). + * This is not valid on an active queue; it is useful only for device + * shutdown. + */ void *virtqueue_detach_unused_buf(struct virtqueue *vq); +/** + * virtqueue_get_vring_size - return the size of the virtqueue's vring + * @vq: the struct virtqueue containing the vring of interest. + * + * Returns the size of the vring. This is mainly used for boasting to + * userspace. Unlike other operations, this need not be serialized. + */ unsigned int virtqueue_get_vring_size(struct virtqueue *vq); /** _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
