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virtio: Introduce virtqueue_get_avail_bytes()

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The current virtqueue_avail_bytes() is oddly named, and checks if a
particular number of bytes are available in a vq.  A better API is to
fetch the number of bytes available in the vq, and let the caller do
what's interesting with the numbers.

Introduce virtqueue_get_avail_bytes(), which returns the number of bytes
for buffers marked for both, in as well as out.  virtqueue_avail_bytes()
is made a wrapper over this new function.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Amit Shah 2012-09-25 00:05:15 +05:30 committed by Michael S. Tsirkin
parent 385ce95d9d
commit 0d8d769085
2 changed files with 25 additions and 8 deletions
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28
hw/virtio.c
View File

@ -335,7 +335,8 @@ static unsigned virtqueue_next_desc(target_phys_addr_t desc_pa,
return next;
}
int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes)
void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
unsigned int *out_bytes)
{
unsigned int idx;
unsigned int total_bufs, in_total, out_total;
@ -380,13 +381,9 @@ int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes)
}
if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
if (in_bytes > 0 &&
(in_total += vring_desc_len(desc_pa, i)) >= in_bytes)
return 1;
in_total += vring_desc_len(desc_pa, i);
} else {
if (out_bytes > 0 &&
(out_total += vring_desc_len(desc_pa, i)) >= out_bytes)
return 1;
out_total += vring_desc_len(desc_pa, i);
}
} while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
@ -395,7 +392,24 @@ int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes)
else
total_bufs++;
}
if (in_bytes) {
*in_bytes = in_total;
}
if (out_bytes) {
*out_bytes = out_total;
}
}
int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
unsigned int out_bytes)
{
unsigned int in_total, out_total;
virtqueue_get_avail_bytes(vq, &in_total, &out_total);
if ((in_bytes && in_bytes < in_total)
|| (out_bytes && out_bytes < out_total)) {
return 1;
}
return 0;
}

5
hw/virtio.h
View File

@ -147,7 +147,10 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
void virtqueue_map_sg(struct iovec *sg, target_phys_addr_t *addr,
size_t num_sg, int is_write);
int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem);
int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes);
int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
unsigned int out_bytes);
void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
unsigned int *out_bytes);
void virtio_notify(VirtIODevice *vdev, VirtQueue *vq);