diff options
Diffstat (limited to 'drivers/virtio/virtio_ring.c')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 35 |
1 files changed, 25 insertions, 10 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 72bf8bc09014..daf659dc06e6 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -18,6 +18,7 @@ */ #include <linux/virtio.h> #include <linux/virtio_ring.h> +#include <linux/virtio_config.h> #include <linux/device.h> #ifdef DEBUG @@ -52,9 +53,6 @@ struct vring_virtqueue /* Number we've added since last sync. */ unsigned int num_added; - /* Last used index we've seen. */ - u16 last_used_idx; - /* How to notify other side. FIXME: commonalize hcalls! */ void (*notify)(struct virtqueue *vq); @@ -87,8 +85,11 @@ static int vring_add_buf(struct virtqueue *_vq, if (vq->num_free < out + in) { pr_debug("Can't add buf len %i - avail = %i\n", out + in, vq->num_free); - /* We notify *even if* VRING_USED_F_NO_NOTIFY is set here. */ - vq->notify(&vq->vq); + /* FIXME: for historical reasons, we force a notify here if + * there are outgoing parts to the buffer. Presumably the + * host should service the ring ASAP. */ + if (out) + vq->notify(&vq->vq); END_USE(vq); return -ENOSPC; } @@ -173,12 +174,13 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head) static inline bool more_used(const struct vring_virtqueue *vq) { - return vq->last_used_idx != vq->vring.used->idx; + return vring_last_used(&vq->vring) != vq->vring.used->idx; } static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len) { struct vring_virtqueue *vq = to_vvq(_vq); + struct vring_used_elem *u; void *ret; unsigned int i; @@ -195,8 +197,11 @@ static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len) return NULL; } - i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id; - *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len; + u = &vq->vring.used->ring[vring_last_used(&vq->vring) % vq->vring.num]; + i = u->id; + *len = u->len; + /* Make sure we don't reload i after doing checks. */ + rmb(); if (unlikely(i >= vq->vring.num)) { BAD_RING(vq, "id %u out of range\n", i); @@ -210,7 +215,7 @@ static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len) /* detach_buf clears data, so grab it now. */ ret = vq->data[i]; detach_buf(vq, i); - vq->last_used_idx++; + vring_last_used(&vq->vring)++; END_USE(vq); return ret; } @@ -294,7 +299,6 @@ struct virtqueue *vring_new_virtqueue(unsigned int num, vq->vq.vq_ops = &vring_vq_ops; vq->notify = notify; vq->broken = false; - vq->last_used_idx = 0; vq->num_added = 0; #ifdef DEBUG vq->in_use = false; @@ -320,4 +324,15 @@ void vring_del_virtqueue(struct virtqueue *vq) } EXPORT_SYMBOL_GPL(vring_del_virtqueue); +/* Manipulates transport-specific feature bits. */ +u32 vring_transport_features(u32 features) +{ + u32 mask = ~VIRTIO_TRANSPORT_F_MASK; + + /* We let through any non-transport bits, and the only one we know. */ + mask &= ~(1 << VIRTIO_RING_F_PUBLISH_INDICES); + return features & mask; +} +EXPORT_SYMBOL_GPL(vring_transport_features); + MODULE_LICENSE("GPL"); |