Patchwork [RESEND,2/3] virtio: Introduce virtqueue_get_avail_bytes()

login
register
mail settings
Submitter Amit Shah
Date Sept. 24, 2012, 6:35 p.m.
Message ID <4ccfac09191ec9a64bdd94bf689939f4ec20f040.1348511596.git.amit.shah@redhat.com>
Download mbox | patch
Permalink /patch/186507/
State New
Headers show

Comments

Amit Shah - Sept. 24, 2012, 6:35 p.m.
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>
---
 hw/virtio.c |   28 +++++++++++++++++++++-------
 hw/virtio.h |    5 ++++-
 2 files changed, 25 insertions(+), 8 deletions(-)

Patch

diff --git a/hw/virtio.c b/hw/virtio.c
index 4c9e20a3..11ac123 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -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;
 }
 
diff --git a/hw/virtio.h b/hw/virtio.h
index 7a4f564..80de375 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -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);