Re: [PATCH v4 09/14] virtio: queue_reset: struct virtio_config_ops add callbacks for queue_reset
From: Jason Wang <hidden>
Date: 2022-02-11 06:49:17
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在 2022/2/9 下午8:28, Xuan Zhuo 写道:
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Performing reset on a queue is divided into four steps: 1. reset_vq: reset one vq 2. recycle the buffer from vq by virtqueue_detach_unused_buf() 3. release the ring of the vq by vring_release_virtqueue() 4. enable_reset_vq: re-enable the reset queue So add two callbacks reset_vq, enable_reset_vq to struct virtio_config_ops. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- include/linux/virtio_config.h | 13 +++++++++++++ 1 file changed, 13 insertions(+)diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index 4d107ad31149..0d01a64f2576 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h@@ -74,6 +74,17 @@ struct virtio_shm_region { * @set_vq_affinity: set the affinity for a virtqueue (optional). * @get_vq_affinity: get the affinity for a virtqueue (optional). * @get_shm_region: get a shared memory region based on the index. + * @reset_vq: reset a queue individually
This needs to be marked as optional I think.
+ * vq: the virtqueue + * Returns 0 on success or error status
It looks to me the caller should also guarantee that the vring is not accsed by any functions e.g NAPI.
+ * After successfully calling this, be sure to call + * virtqueue_detach_unused_buf() to recycle the buffer in the ring, and + * then call vring_release_virtqueue() to release the vq ring. + * @enable_reset_vq: enable a reset queue + * vq: the virtqueue + * ring_num: specify ring num for the vq to be re-enabled. 0 means use the + * default value. MUST be a power of 2.
Note that we don't have power of 2 requirement for packed virtqueue. And I wonder if it's cleaner to have a find_vq() ops instead to dealing with the re-allocation and possible size change, or have a dedicated helper to set vring size so driver can do. reset_vq() virtqueue_set_vring_size() enable_reset_vq()
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+ * Returns 0 on success or error status */ typedef void vq_callback_t(struct virtqueue *); struct virtio_config_ops {@@ -100,6 +111,8 @@ struct virtio_config_ops { int index); bool (*get_shm_region)(struct virtio_device *vdev, struct virtio_shm_region *region, u8 id); + int (*reset_vq)(struct virtqueue *vq); + int (*enable_reset_vq)(struct virtqueue *vq, u16 ring_num);
Note that the current implement is best-effort, so it's not guarantee that we can have a vring with ring_num, we may get less under memory pressure or even fail. We probably need to have a pamater to mandate the ring_num otherwise user may surprise to see a decreased size of the ring when a increasing is actually requested. Thanks
}; /* If driver didn't advertise the feature, it will never appear. */
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