From 86e9424d7252bae5ad1c17b4b8088193e6b27cbe Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 17 Feb 2010 19:11:33 +0200 Subject: 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 Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 6eb15259f5a..db21518f7e8 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); } -- cgit v1.2.3