Re: [kvm-devel] [PATCH] kvm balloon guest driver (v2)

[Marcelo T. <ma...@kv...>]

On Thu, Jan 10, 2008 at 04:11:51PM +0900, Akio Takebe wrote:
> Hi, Marcelo
> 
> >+struct balloon_buf *alloc_balloon_buf(struct virtio_device *vdev, gfp_t 
> >flags)
> >+{
> >+	struct balloon_buf *buf;
> >+
> >+	buf = kzalloc(sizeof(struct balloon_buf), flags);
> >+	if (!buf)
> >+		dev_printk(KERN_ERR, &vdev->dev, "%s: alloc fail\n", __func__);
> >+
> >+	return buf;
> >+}
> >+
> [snip..]
> >+static int kvm_balloon_inflate(struct virtballoon *v, int32_t npages)
> >+{
> >+	LIST_HEAD(tmp_list);
> >+	struct page *page, *tmp;
> >+	struct balloon_buf *buf;
> >+	u32 *pfn;
> >+	int allocated = 0;
> >+	int i, r = -ENOMEM;
> >+
> >+	buf = alloc_balloon_buf(v->vdev, GFP_KERNEL);
> When does balloon driver free the buf?

Hi Akio,

The buffers are passed from the virtio handling routine to the balloon_thread
through the balloon_work list, and then freed here:

+               spin_lock_irq(&v->queue_lock);
+               while (!list_empty(&v->balloon_work)) {
+                       struct balloon_work *work;
+                       struct balloon_buf *buf;
+
+                       work = list_entry(v->balloon_work.next,
+                                        struct balloon_work, list);
+                       list_del(&work->list);
+                       spin_unlock_irq(&v->queue_lock);
+                       buf = work->buf;
+                       kfree(work);
+
+                       switch(buf->hdr.cmd) {
+                       case CMD_BALLOON_DEFLATE:
+                               deflate_done(v, buf);
+                               break;
+                       case CMD_BALLOON_INFLATE:
+                               inflate_done(v, buf);
+                               break;
+                       default:
+                               printk("%s: unknown cmd 0x%x\n", __func__,
+                                       buf->hdr.cmd);
+                       }
+                       kfree(buf);