This is a note to let you know that I've just added the patch titled
vhost-scsi: Handle vhost_vq_work_queue failures for events
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vhost-scsi-handle-vhost_vq_work_queue-failures-for-e.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 89c97a3d4818b4f0bd5b7afe195fc87e601cc540
Author: Mike Christie <michael.christie@xxxxxxxxxx>
Date: Fri Mar 15 19:46:59 2024 -0500
vhost-scsi: Handle vhost_vq_work_queue failures for events
[ Upstream commit b1b2ce58ed23c5d56e0ab299a5271ac01f95b75c ]
Currently, we can try to queue an event's work before the vhost_task is
created. When this happens we just drop it in vhost_scsi_do_plug before
even calling vhost_vq_work_queue. During a device shutdown we do the
same thing after vhost_scsi_clear_endpoint has cleared the backends.
In the next patches we will be able to kill the vhost_task before we
have cleared the endpoint. In that case, vhost_vq_work_queue can fail
and we will leak the event's memory. This has handle the failure by
just freeing the event. This is safe to do, because
vhost_vq_work_queue will only return failure for us when the vhost_task
is killed and so userspace will not be able to handle events if we
sent them.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
Message-Id: <20240316004707.45557-2-michael.christie@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 282aac45c6909..f34f9895b8984 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -497,10 +497,8 @@ vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
vq_err(vq, "Faulted on vhost_scsi_send_event\n");
}
-static void vhost_scsi_evt_work(struct vhost_work *work)
+static void vhost_scsi_complete_events(struct vhost_scsi *vs, bool drop)
{
- struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
- vs_event_work);
struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
struct vhost_scsi_evt *evt, *t;
struct llist_node *llnode;
@@ -508,12 +506,20 @@ static void vhost_scsi_evt_work(struct vhost_work *work)
mutex_lock(&vq->mutex);
llnode = llist_del_all(&vs->vs_event_list);
llist_for_each_entry_safe(evt, t, llnode, list) {
- vhost_scsi_do_evt_work(vs, evt);
+ if (!drop)
+ vhost_scsi_do_evt_work(vs, evt);
vhost_scsi_free_evt(vs, evt);
}
mutex_unlock(&vq->mutex);
}
+static void vhost_scsi_evt_work(struct vhost_work *work)
+{
+ struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
+ vs_event_work);
+ vhost_scsi_complete_events(vs, false);
+}
+
static int vhost_scsi_copy_sgl_to_iov(struct vhost_scsi_cmd *cmd)
{
struct iov_iter *iter = &cmd->saved_iter;
@@ -1509,7 +1515,8 @@ vhost_scsi_send_evt(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
}
llist_add(&evt->list, &vs->vs_event_list);
- vhost_vq_work_queue(vq, &vs->vs_event_work);
+ if (!vhost_vq_work_queue(vq, &vs->vs_event_work))
+ vhost_scsi_complete_events(vs, true);
}
static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
