On Thu, Apr 18, 2013 at 09:05:53AM +0800, Asias He wrote:
> Signed-off-by: Asias He <asias@xxxxxxxxxx>
> ---
> drivers/vhost/tcm_vhost.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index 88ebb79..8f05528 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -111,6 +111,24 @@ static bool tcm_vhost_check_feature(struct vhost_scsi *vs, int feature)
> return ret;
> }
>
> +static bool tcm_vhost_check_endpoint(struct vhost_virtqueue *vq)
> +{
> + bool ret = false;
> +
> + /*
> + * We can handle the vq only after the endpoint is setup by calling the
> + * VHOST_SCSI_SET_ENDPOINT ioctl.
> + *
> + * TODO: Check that we are running from vhost_worker which acts
> + * as read-side critical section for vhost kind of RCU.
> + * See the comments in struct vhost_virtqueue in drivers/vhost/vhost.h
> + */
> + if (rcu_dereference_check(vq->private_data, 1))
> + ret = true;
> +
> + return ret;
> +}
> +
You can't use RCU in this way. You need to actually
derefence. Instead, just move this within vq mutex
and do rcu_dereference_protected. document that this function
requires vq mutex.
> static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
> {
> return 1;
> --
> 1.8.1.4
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