[PATCH 5.17 750/772] vdpasim: allow to enable a vq repeatedly

Greg Kroah-Hartman
2022-06-07T21:54:49Z

From: Eugenio Pérez <eperezma@redhat.com>

commit 242436973831aa97e8ce19533c6c912ea8def31b upstream.

Code must be resilient to enable a queue many times.

At the moment the queue is resetting so it's definitely not the expected
behavior.

v2: set vq->ready = 0 at disable.

Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator")
Cc: stable@vger.kernel.org
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20220519145919.772896-1-eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -353,11 +353,14 @@ static void vdpasim_set_vq_ready(struct
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
+ bool old_ready;

spin_lock(&vdpasim->lock);
+ old_ready = vq->ready;
vq->ready = ready;
- if (vq->ready)
+ if (vq->ready && !old_ready) {
vdpasim_queue_ready(vdpasim, idx);
+ }
spin_unlock(&vdpasim->lock);
}