On Friday, January 4, 2019 11:45 PM, Michael S. Tsirkin wrote:
> > struct virtio_balloon {
> > struct virtio_device *vdev;
> > struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
> > @@ -77,6 +81,8 @@ struct virtio_balloon {
> > /* Prevent updating balloon when it is being canceled. */
> > spinlock_t stop_update_lock;
> > bool stop_update;
> > + /* Bitmap to indicate if reading the related config fields are needed
> */
> > + unsigned long config_read_bitmap;
> >
> > /* The list of allocated free pages, waiting to be given back to mm */
> > struct list_head free_page_list;
>
> It seems that you never initialize this bitmap. Probably harmless here but
> generally using uninitialized memory isn't good.
We've used kzalloc to allocate the vb struct, so it's already 0-initialized :)
> > +
> > static int send_free_pages(struct virtio_balloon *vb) {
> > int err;
> > @@ -620,6 +630,7 @@ static int send_free_pages(struct virtio_balloon *vb)
> > * stop the reporting.
> > */
> > cmd_id_active = virtio32_to_cpu(vb->vdev, vb-
> >cmd_id_active);
> > + virtio_balloon_read_cmd_id_received(vb);
[1]
> > if (cmd_id_active != vb->cmd_id_received)
> > break;
> >
> > @@ -637,11 +648,9 @@ static int send_free_pages(struct virtio_balloon
> *vb)
> > return 0;
> > }
> >
> > -static void report_free_page_func(struct work_struct *work)
> > +static void virtio_balloon_report_free_page(struct virtio_balloon
> > +*vb)
> > {
> > int err;
> > - struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
> > - report_free_page_work);
> > struct device *dev = &vb->vdev->dev;
> >
> > /* Start by sending the received cmd id to host with an outbuf. */
> > @@ -659,6 +668,22 @@ static void report_free_page_func(struct
> work_struct *work)
> > dev_err(dev, "Failed to send a stop id, err = %d\n", err); }
> >
> > +static void report_free_page_func(struct work_struct *work) {
> > + struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
> > + report_free_page_work);
> > +
> > + virtio_balloon_read_cmd_id_received(vb);
>
> This will not achieve what you are trying to do, which is cancel reporting if it's
> in progress.
>
> You need to re-read each time you compare to cmd_id_active.
Yes, already did, please see [1] above
> An API similar to
> u32 virtio_balloon_cmd_id_received(vb)
> seems to be called for, and I would rename cmd_id_received to
> cmd_id_received_cache to make sure we caught all users.
>
I'm not sure about adding "cache" here, cmd_id_received refers to the cmd id
that the driver just received from the device. There is one called "cmd_id_active" which
is the one that the driver is actively using.
So cmd_id_received is already a "cache" to " cmd_id_active " in some sense.
Best,
Wei
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