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authorLadi Prosek <lprosek@redhat.com>2017-03-24 15:24:50 +0100
committerGerd Hoffmann <kraxel@redhat.com>2017-03-27 12:14:45 +0200
commit57094547dfea4ce784923b8abb53ac3ab4e3961a (patch)
tree439ffe430c2e91d781e8280bc56aeae8585eaf88 /hw/input
parent0f5a15e40ad1512c70d1323a73c7b073e32e17ee (diff)
virtio-input: fix eventq batching
virtio_input_send buffers input events until it sees a SYNC. Then it either sends or drops the entire batch, depending on whether eventq has enough space available. The case to avoid here is partial sends where only part of the batch would get to the guest. Using virtqueue_get_avail_bytes to check the state of eventq was not correct. The queue may have a smaller number of larger buffers available so bytes may be enough but the batch would still not be possible to send, leading to the "Huh? No vq elem available" error. Instead of checking available bytes, this patch optimistically pops buffers from the queue and puts them back in case it runs out of space and the batch needs to be dropped. Signed-off-by: Ladi Prosek <lprosek@redhat.com> Message-id: 1490365490-4854-3-git-send-email-lprosek@redhat.com Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'hw/input')
-rw-r--r--hw/input/virtio-input.c29
1 files changed, 14 insertions, 15 deletions
diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c
index 728832aa62..0e42f0d02c 100644
--- a/hw/input/virtio-input.c
+++ b/hw/input/virtio-input.c
@@ -22,7 +22,6 @@
void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event)
{
VirtQueueElement *elem;
- unsigned have, need;
int i, len;
if (!vinput->active) {
@@ -33,9 +32,9 @@ void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event)
if (vinput->qindex == vinput->qsize) {
vinput->qsize++;
vinput->queue = g_realloc(vinput->queue, vinput->qsize *
- sizeof(virtio_input_event));
+ sizeof(vinput->queue[0]));
}
- vinput->queue[vinput->qindex++] = *event;
+ vinput->queue[vinput->qindex++].event = *event;
/* ... until we see a report sync ... */
if (event->type != cpu_to_le16(EV_SYN) ||
@@ -44,24 +43,24 @@ void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event)
}
/* ... then check available space ... */
- need = sizeof(virtio_input_event) * vinput->qindex;
- virtqueue_get_avail_bytes(vinput->evt, &have, NULL, need, 0);
- if (have < need) {
- vinput->qindex = 0;
- trace_virtio_input_queue_full();
- return;
- }
-
- /* ... and finally pass them to the guest */
for (i = 0; i < vinput->qindex; i++) {
elem = virtqueue_pop(vinput->evt, sizeof(VirtQueueElement));
if (!elem) {
- /* should not happen, we've checked for space beforehand */
- fprintf(stderr, "%s: Huh? No vq elem available ...\n", __func__);
+ while (--i >= 0) {
+ virtqueue_unpop(vinput->evt, vinput->queue[i].elem, 0);
+ }
+ vinput->qindex = 0;
+ trace_virtio_input_queue_full();
return;
}
+ vinput->queue[i].elem = elem;
+ }
+
+ /* ... and finally pass them to the guest */
+ for (i = 0; i < vinput->qindex; i++) {
+ elem = vinput->queue[i].elem;
len = iov_from_buf(elem->in_sg, elem->in_num,
- 0, vinput->queue+i, sizeof(virtio_input_event));
+ 0, &vinput->queue[i].event, sizeof(virtio_input_event));
virtqueue_push(vinput->evt, elem, len);
g_free(elem);
}