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authorMichael S. Tsirkin <mst@redhat.com>2010-02-17 19:11:33 +0200
committerMichael S. Tsirkin <mst@redhat.com>2010-02-28 19:42:35 +0200
commit86e9424d7252bae5ad1c17b4b8088193e6b27cbe (patch)
treeff6bbcf61d5518bd4e06f4cd09c20a4b1f6fcaa4 /drivers/vhost/vhost.c
parent655ffee284dfcf9a24ac0343f3e5ee6db85b85c5 (diff)
vhost: logging thinko fix
vhost was dong some complex math to get offset to log at, and got it wrong by a couple of bytes, while in fact it's simple: get address where we write, subtract start of buffer, add log base. Do it this way. Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/vhost/vhost.c')
-rw-r--r--drivers/vhost/vhost.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6eb15259f5ae..db21518f7e8d 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1004,10 +1004,14 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len)
if (unlikely(vq->log_used)) {
/* Make sure data is seen before log. */
smp_wmb();
- log_write(vq->log_base, vq->log_addr + sizeof *vq->used->ring *
- (vq->last_used_idx % vq->num),
- sizeof *vq->used->ring);
- log_write(vq->log_base, vq->log_addr, sizeof *vq->used->ring);
+ /* Log used ring entry write. */
+ log_write(vq->log_base,
+ vq->log_addr + ((void *)used - (void *)vq->used),
+ sizeof *used);
+ /* Log used index update. */
+ log_write(vq->log_base,
+ vq->log_addr + offsetof(struct vring_used, idx),
+ sizeof vq->used->idx);
if (vq->log_ctx)
eventfd_signal(vq->log_ctx, 1);
}