Re: [PATCH v8 11/16] virtio_ring: packed: extract the logic of alloc queue

[Jason Wang]

在 2022/3/14 下午5:34, Xuan Zhuo 写道:
Separate the logic of packed to create vring queue.
For the convenience of passing parameters, add a structure
vring_packed.

This feature is required for subsequent virtuqueue reset vring.

Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---
  drivers/virtio/virtio_ring.c | 121 ++++++++++++++++++++++++++---------
  1 file changed, 92 insertions(+), 29 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a15869514146..96ff2dabda14 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -85,6 +85,18 @@ struct vring_desc_extra {
        u16 next;                       /* The next desc state in a list. */
  };
  
+struct vring_packed {
+       u32 num;
+       struct vring_packed_desc *ring;
+       struct vring_packed_desc_event *driver;
+       struct vring_packed_desc_event *device;
+       dma_addr_t ring_dma_addr;
+       dma_addr_t driver_event_dma_addr;
+       dma_addr_t device_event_dma_addr;
+       size_t ring_size_in_bytes;
+       size_t event_size_in_bytes;
+};
+


Interesting,  a nitpick here is that if it is only used by one helper, 
it's probably not worth to bother.

And if we want to do that, we need

1) use a separated patch

2) do it for split virtqueue as well

Thanks


  struct vring_virtqueue {
        struct virtqueue vq;
  
@@ -1735,45 +1747,101 @@ static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num)
        return desc_extra;
  }
  
-static struct virtqueue *vring_create_virtqueue_packed(
-       unsigned int index,
-       unsigned int num,
-       unsigned int vring_align,
-       struct virtio_device *vdev,
-       bool weak_barriers,
-       bool may_reduce_num,
-       bool context,
-       bool (*notify)(struct virtqueue *),
-       void (*callback)(struct virtqueue *),
-       const char *name)
+static void vring_free_vring_packed(struct vring_packed *vring,
+                                   struct virtio_device *vdev)
+{
+       dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
+       struct vring_packed_desc_event *driver, *device;
+       size_t ring_size_in_bytes, event_size_in_bytes;
+       struct vring_packed_desc *ring;
+
+       ring                  = vring->ring;
+       driver                = vring->driver;
+       device                = vring->device;
+       ring_size_in_bytes    = vring->ring_size_in_bytes;
+       event_size_in_bytes   = vring->event_size_in_bytes;
+       ring_dma_addr         = vring->ring_dma_addr;
+       driver_event_dma_addr = vring->driver_event_dma_addr;
+       device_event_dma_addr = vring->device_event_dma_addr;
+
+       if (device)
+               vring_free_queue(vdev, event_size_in_bytes, device, 
device_event_dma_addr);
+
+       if (driver)
+               vring_free_queue(vdev, event_size_in_bytes, driver, 
driver_event_dma_addr);
+
+       if (ring)
+               vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
+}
+
+static int vring_alloc_queue_packed(struct vring_packed *vring,
+                                   struct virtio_device *vdev,
+                                   u32 num)
  {
-       struct vring_virtqueue *vq;
        struct vring_packed_desc *ring;
        struct vring_packed_desc_event *driver, *device;
        dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
        size_t ring_size_in_bytes, event_size_in_bytes;
  
+	memset(vring, 0, sizeof(*vring));
+
        ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
  
  	ring = vring_alloc_queue(vdev, ring_size_in_bytes,
                                 &ring_dma_addr,
                                 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
        if (!ring)
-               goto err_ring;
+               goto err;
+
+       vring->num = num;
+       vring->ring = ring;
+       vring->ring_size_in_bytes = ring_size_in_bytes;
+       vring->ring_dma_addr = ring_dma_addr;
  
  	event_size_in_bytes = sizeof(struct vring_packed_desc_event);
+       vring->event_size_in_bytes = event_size_in_bytes;
  
  	driver = vring_alloc_queue(vdev, event_size_in_bytes,
                                   &driver_event_dma_addr,
                                   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
        if (!driver)
-               goto err_driver;
+               goto err;
+
+       vring->driver = driver;
+       vring->driver_event_dma_addr = driver_event_dma_addr;
  
  	device = vring_alloc_queue(vdev, event_size_in_bytes,
                                   &device_event_dma_addr,
                                   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
        if (!device)
-               goto err_device;
+               goto err;
+
+       vring->device = device;
+       vring->device_event_dma_addr = device_event_dma_addr;
+       return 0;
+
+err:
+       vring_free_vring_packed(vring, vdev);
+       return -ENOMEM;
+}
+
+static struct virtqueue *vring_create_virtqueue_packed(
+       unsigned int index,
+       unsigned int num,
+       unsigned int vring_align,
+       struct virtio_device *vdev,
+       bool weak_barriers,
+       bool may_reduce_num,
+       bool context,
+       bool (*notify)(struct virtqueue *),
+       void (*callback)(struct virtqueue *),
+       const char *name)
+{
+       struct vring_virtqueue *vq;
+       struct vring_packed vring;
+
+       if (vring_alloc_queue_packed(&vring, vdev, num))
+               goto err_vq;
  
  	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
        if (!vq)
@@ -1805,17 +1873,17 @@ static struct virtqueue *vring_create_virtqueue_packed(
        if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
                vq->weak_barriers = false;
  
-	vq->packed.ring_dma_addr = ring_dma_addr;
-       vq->packed.driver_event_dma_addr = driver_event_dma_addr;
-       vq->packed.device_event_dma_addr = device_event_dma_addr;
+       vq->packed.ring_dma_addr = vring.ring_dma_addr;
+       vq->packed.driver_event_dma_addr = vring.driver_event_dma_addr;
+       vq->packed.device_event_dma_addr = vring.device_event_dma_addr;
  
-	vq->packed.ring_size_in_bytes = ring_size_in_bytes;
-       vq->packed.event_size_in_bytes = event_size_in_bytes;
+       vq->packed.ring_size_in_bytes = vring.ring_size_in_bytes;
+       vq->packed.event_size_in_bytes = vring.event_size_in_bytes;
  
  	vq->packed.vring.num = num;
-       vq->packed.vring.desc = ring;
-       vq->packed.vring.driver = driver;
-       vq->packed.vring.device = device;
+       vq->packed.vring.desc = vring.ring;
+       vq->packed.vring.driver = vring.driver;
+       vq->packed.vring.device = vring.device;
  
  	vq->packed.next_avail_idx = 0;
        vq->packed.avail_wrap_counter = 1;
@@ -1856,12 +1924,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
  err_desc_state:
        kfree(vq);
  err_vq:
-       vring_free_queue(vdev, event_size_in_bytes, device, 
device_event_dma_addr);
-err_device:
-       vring_free_queue(vdev, event_size_in_bytes, driver, 
driver_event_dma_addr);
-err_driver:
-       vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
-err_ring:
+       vring_free_vring_packed(&vring, vdev);
        return NULL;
  }
  

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