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authorRusty Russell <rusty@rustcorp.com.au>2008-07-29 10:58:34 -0400
committerRusty Russell <rusty@rustcorp.com.au>2008-07-28 19:58:35 -0400
commitb5111790fa6695b1502d4f5d389f6b22b9de10c3 (patch)
treef937d643aaf845ecd7952055fcb6c4d8b879e040 /Documentation
parentcf485e566bc4a8098680162e1cc2ac1dfbef8a3c (diff)
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: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/lguest/lguest.c16
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,
191 return iov->iov_base; 191 return iov->iov_base;
192} 192}
193 193
194/* Wrapper for the last available index. Makes it easier to change. */
195#define lg_last_avail(vq) ((vq)->last_avail_idx)
196
194/* The virtio configuration space is defined to be little-endian. x86 is 197/* The virtio configuration space is defined to be little-endian. x86 is
195 * little-endian too, but it's nice to be explicit so we have these helpers. */ 198 * little-endian too, but it's nice to be explicit so we have these helpers. */
196#define cpu_to_le16(v16) (v16) 199#define cpu_to_le16(v16) (v16)
@@ -690,19 +693,22 @@ static unsigned get_vq_desc(struct virtqueue *vq,
690 unsigned int *out_num, unsigned int *in_num) 693 unsigned int *out_num, unsigned int *in_num)
691{ 694{
692 unsigned int i, head; 695 unsigned int i, head;
696 u16 last_avail;
693 697
694 /* Check it isn't doing very strange things with descriptor numbers. */ 698 /* Check it isn't doing very strange things with descriptor numbers. */
695 if ((u16)(vq->vring.avail->idx - vq->last_avail_idx) > vq->vring.num) 699 last_avail = lg_last_avail(vq);
700 if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
696 errx(1, "Guest moved used index from %u to %u", 701 errx(1, "Guest moved used index from %u to %u",
697 vq->last_avail_idx, vq->vring.avail->idx); 702 last_avail, vq->vring.avail->idx);
698 703
699 /* If there's nothing new since last we looked, return invalid. */ 704 /* If there's nothing new since last we looked, return invalid. */
700 if (vq->vring.avail->idx == vq->last_avail_idx) 705 if (vq->vring.avail->idx == last_avail)
701 return vq->vring.num; 706 return vq->vring.num;
702 707
703 /* Grab the next descriptor number they're advertising, and increment 708 /* Grab the next descriptor number they're advertising, and increment
704 * the index we've seen. */ 709 * the index we've seen. */
705 head = vq->vring.avail->ring[vq->last_avail_idx++ % vq->vring.num]; 710 head = vq->vring.avail->ring[last_avail % vq->vring.num];
711 lg_last_avail(vq)++;
706 712
707 /* If their number is silly, that's a fatal mistake. */ 713 /* If their number is silly, that's a fatal mistake. */
708 if (head >= vq->vring.num) 714 if (head >= vq->vring.num)
@@ -980,7 +986,7 @@ static void update_device_status(struct device *dev)
980 for (vq = dev->vq; vq; vq = vq->next) { 986 for (vq = dev->vq; vq; vq = vq->next) {
981 memset(vq->vring.desc, 0, 987 memset(vq->vring.desc, 0,
982 vring_size(vq->config.num, getpagesize())); 988 vring_size(vq->config.num, getpagesize()));
983 vq->last_avail_idx = 0; 989 lg_last_avail(vq) = 0;
984 } 990 }
985 } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { 991 } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) {
986 warnx("Device %s configuration FAILED", dev->name); 992 warnx("Device %s configuration FAILED", dev->name);