diff options
| author | Jason Wang <jasowang@redhat.com> | 2016-03-04 06:24:52 -0500 |
|---|---|---|
| committer | Alistair Strachan <astrachan@google.com> | 2019-05-14 17:56:53 -0700 |
| commit | 179cda3b96b1edc266daa8773938f64c6a0639e1 (patch) | |
| tree | 778d24125b59b2ba04c33944e49073c43e38752d /drivers/vhost | |
| parent | eb7e61ae8c0aa8b1e9d3e36a055785da096d0f0e (diff) | |
UPSTREAM: vhost: introduce vhost_vq_avail_empty()
This patch introduces a helper which will return true if we're sure
that the available ring is empty for a specific vq. When we're not
sure, e.g vq access failure, return false instead. This could be used
for busy polling code to exit the busy loop.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit d4a60603fa0b42012decfa058dfa44cffde7a10c)
Bug: 121166534
Test: Ran cuttlefish with android-4.4 + VSOCKETS, VMWARE_VMCI_VSOCKETS
Signed-off-by: Alistair Strachan <astrachan@google.com>
Change-Id: I1d4e972543470530a5bc37e19f4199b1f345e042
Diffstat (limited to 'drivers/vhost')
| -rw-r--r-- | drivers/vhost/vhost.c | 14 | ||||
| -rw-r--r-- | drivers/vhost/vhost.h | 1 |
2 files changed, 15 insertions, 0 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 65a1d2da114a..73d4545ee0d3 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1661,6 +1661,20 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev, } EXPORT_SYMBOL_GPL(vhost_add_used_and_signal_n); +/* return true if we're sure that avaiable ring is empty */ +bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq) +{ + __virtio16 avail_idx; + int r; + + r = __get_user(avail_idx, &vq->avail->idx); + if (r) + return false; + + return vhost16_to_cpu(vq, avail_idx) == vq->avail_idx; +} +EXPORT_SYMBOL_GPL(vhost_vq_avail_empty); + /* OK, now we need to know about added descriptors. */ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) { diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index eef33b11a7ed..af5af773bf7a 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -159,6 +159,7 @@ void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *, struct vring_used_elem *heads, unsigned count); void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *); void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *); +bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *); bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *); int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, |