On (Tue) 14 Jul 2015 [13:03:10], Pankaj Gupta wrote:
> We are arming timer when we get first request from guest.
> Even if guest pulls all the data we will be serving guest
> only when timer bumps up new quota. When timer expires
> we check if we have a pending request from guest, we
> serve it and rearm the timer else we don't do any thing.
>
> This patch also moves out 'request size' logic out to
> 'check_request' function so that can be re-used.
>
> Signed-off-by: Pankaj Gupta <pagu...@redhat.com>
> ---
> hw/virtio/virtio-rng.c | 36 ++++++++++++++++++++++++------------
> 1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
> index 8774a0c..dca5064 100644
> --- a/hw/virtio/virtio-rng.c
> +++ b/hw/virtio/virtio-rng.c
> @@ -37,6 +37,24 @@ static size_t get_request_size(VirtQueue *vq, unsigned
> quota)
> return in;
> }
>
> +static size_t check_request(VirtIORNG *vrng)
> +{
> + size_t size;
> + unsigned quota;
> +
> + if (vrng->quota_remaining < 0) {
> + quota = 0;
> + } else {
> + quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
> + }
> + size = get_request_size(vrng->vq, quota);
> +
> + trace_virtio_rng_request(vrng, size, quota);
> +
> + size = MIN(vrng->quota_remaining, size);
> + return size;
> +}
> +
> static void virtio_rng_process(VirtIORNG *vrng);
>
> /* Send data from a char device over to the guest */
> @@ -72,7 +90,6 @@ static void chr_read(void *opaque, const void *buf, size_t
> size)
> static void virtio_rng_process(VirtIORNG *vrng)
> {
> size_t size;
> - unsigned quota;
>
> if (!is_guest_ready(vrng)) {
> return;
> @@ -83,17 +100,8 @@ static void virtio_rng_process(VirtIORNG *vrng)
> qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
> vrng->conf.period_ms);
> vrng->activate_timer = false;
> }
> + size = check_request(vrng);
>
> - if (vrng->quota_remaining < 0) {
> - quota = 0;
> - } else {
> - quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
> - }
> - size = get_request_size(vrng->vq, quota);
> -
> - trace_virtio_rng_request(vrng, size, quota);
> -
> - size = MIN(vrng->quota_remaining, size);
> if (size) {
> rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
> }
> @@ -142,9 +150,13 @@ static int virtio_rng_load(QEMUFile *f, void *opaque,
> int version_id)
> static void check_rate_limit(void *opaque)
> {
> VirtIORNG *vrng = opaque;
> + size_t size;
>
> vrng->quota_remaining = vrng->conf.max_bytes;
> - virtio_rng_process(vrng);
> + size = check_request(vrng);
> + if (size > 0) {
> + virtio_rng_process(vrng);
> + }
Why is it necessary to call check_request() here, instead of just
calling get_request_size()? We want to call virtio_rng_process() in
case the guest has queued up another buffer, and for that,
get_request_size() is sufficient. check_request() is anyway something
that virtio_rng_process() is going to do as soon as it's called...
Amit
