Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b5111790 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: wrap last_avail accesses. 



To simplify the transition to when we publish indices in the ring
(and make shuffling my patch queue easier), wrap them in a lg_last_avail()
macro.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent cf485e56

Documentation/lguest/lguest.c

+11 −5
Original line number Diff line number Diff line
@@ -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);