diff options
| -rw-r--r-- | Documentation/lguest/lguest.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index a1fca9db788e..31a688e105ca 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -191,6 +191,9 @@ static void *_convert(struct iovec *iov, size_t size, size_t align, return iov->iov_base; } +/* Wrapper for the last available index. Makes it easier to change. */ +#define lg_last_avail(vq) ((vq)->last_avail_idx) + /* The virtio configuration space is defined to be little-endian. x86 is * little-endian too, but it's nice to be explicit so we have these helpers. */ #define cpu_to_le16(v16) (v16) @@ -690,19 +693,22 @@ static unsigned get_vq_desc(struct virtqueue *vq, unsigned int *out_num, unsigned int *in_num) { unsigned int i, head; + u16 last_avail; /* Check it isn't doing very strange things with descriptor numbers. */ - if ((u16)(vq->vring.avail->idx - vq->last_avail_idx) > vq->vring.num) + last_avail = lg_last_avail(vq); + if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num) errx(1, "Guest moved used index from %u to %u", - vq->last_avail_idx, vq->vring.avail->idx); + last_avail, vq->vring.avail->idx); /* If there's nothing new since last we looked, return invalid. */ - if (vq->vring.avail->idx == vq->last_avail_idx) + if (vq->vring.avail->idx == last_avail) return vq->vring.num; /* Grab the next descriptor number they're advertising, and increment * the index we've seen. */ - head = vq->vring.avail->ring[vq->last_avail_idx++ % vq->vring.num]; + head = vq->vring.avail->ring[last_avail % vq->vring.num]; + lg_last_avail(vq)++; /* If their number is silly, that's a fatal mistake. */ if (head >= vq->vring.num) @@ -980,7 +986,7 @@ static void update_device_status(struct device *dev) for (vq = dev->vq; vq; vq = vq->next) { memset(vq->vring.desc, 0, vring_size(vq->config.num, getpagesize())); - vq->last_avail_idx = 0; + lg_last_avail(vq) = 0; } } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { warnx("Device %s configuration FAILED", dev->name); |