Re: [Qemu-devel] [PATCH WIP 0/4] vhost-scsi: new device supporting the tcm_vhost Linux kernel module

[Nicholas A. Bellinger]

On Thu, 2013-01-31 at 13:12 +0200, Michael S. Tsirkin wrote:
> On Wed, Jan 30, 2013 at 05:41:22PM +0100, Paolo Bonzini wrote:

<SNIP>

> > Another small bug I found is an ordering problem between
> > VHOST_SET_VRING_KICK and VHOST_SCSI_SET_ENDPOINT.  Starting the vq
> > causes a "vhost_scsi_handle_vq endpoint not set" error in dmesg.
> > Because of this I added the first two patches, which let me do
> > VHOST_SCSI_SET_ENDPOINT before VHOST_SET_VRING_KICK but after setting
> > up the vring.
> > 
> > Unfortunately, this is not enough to fix the hang.  And anyway, it's
> > probably simpler to avoid the two patches and remove this test from the
> > tcm_vhost.c vhost_scsi_set/clear_endpoint functions:
> > 
> >         mutex_lock(&vs->dev.mutex);
> >         /* Verify that ring has been setup correctly. */
> >         for (index = 0; index < vs->dev.nvqs; ++index) {
> >                 /* Verify that ring has been setup correctly. */
> >                 if (!vhost_vq_access_ok(&vs->vqs[index])) {
> >                         mutex_unlock(&vs->dev.mutex);
> >                         return -EFAULT;
> >                 }
> >         }
> >         mutex_unlock(&vs->dev.mutex);
> 
> Well userspace should initialize the kick eventfd to 0,
> it seems to init it to 1 which is why we get the error.
> But I think the only issue is pr_err: vhost-net already
> ignores such a kick with no backend. So let's just
> remove it, preferably for 3.8.
> 

That's fine with me.  Applying to target-pending/master, and will
include in the next PULL request for v3.8.0.

Thanks,

--nab

> --->
> tcm_vhost: fix pr_err on early kick
> 
> It's OK to get kick before backend is set or after
> it is cleared, we can just ignore it.
> 
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> 
> ---
> 
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index b20df5c..22321cf 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -575,10 +575,8 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
>  
>       /* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
>       tv_tpg = vs->vs_tpg;
> -     if (unlikely(!tv_tpg)) {
> -             pr_err("%s endpoint not set\n", __func__);
> +     if (unlikely(!tv_tpg))
>               return;
> -     }
>  
>       mutex_lock(&vq->mutex);
>       vhost_disable_notify(&vs->dev, vq);