| Message ID | 20210916103336.7243-3-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] firmware: arm_scmi: Review some virtio log messages | expand |
Hi Michael, On Thu, Sep 16, 2021 at 11:33:36AM +0100, Cristian Marussi wrote: > Only one single SCMI Virtio device is currently supported by this driver > and it is referenced using a static global variable which is initialized > once for all during probing and nullified at virtio device removal. > > Add proper SMP barriers to protect accesses to such device reference to > ensure that the initialzation state of such device is correctly observed by > all PEs at any time. > > Return -EBUSY, instead of -EINVAL, and a descriptive error message if more > than one SCMI Virtio device is ever found and probed. > I was thinking of applying this patch and probably 2/3 as fix for v5.15. Let me know if you have any objections. -- Regards, Sudeep
diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c index 633b5bc379a4..3671986ea056 100644 --- a/drivers/firmware/arm_scmi/virtio.c +++ b/drivers/firmware/arm_scmi/virtio.c @@ -389,8 +389,11 @@ static int scmi_vio_probe(struct virtio_device *vdev) struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT]; /* Only one SCMI VirtiO device allowed */ - if (scmi_vdev) - return -EINVAL; + if (scmi_vdev) { + dev_err(dev, + "One SCMI Virtio device was already initialized: only one allowed.\n"); + return -EBUSY; + } have_vq_rx = scmi_vio_have_vq_rx(vdev); vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1; @@ -433,7 +436,8 @@ static int scmi_vio_probe(struct virtio_device *vdev) } vdev->priv = channels; - scmi_vdev = vdev; + /* Ensure initialized scmi_vdev is visible */ + smp_store_mb(scmi_vdev, vdev); return 0; } @@ -449,7 +453,8 @@ static void scmi_vio_remove(struct virtio_device *vdev) */ vdev->config->reset(vdev); vdev->config->del_vqs(vdev); - scmi_vdev = NULL; + /* Ensure scmi_vdev is visible as NULL */ + smp_store_mb(scmi_vdev, NULL); } static int scmi_vio_validate(struct virtio_device *vdev)
Only one single SCMI Virtio device is currently supported by this driver and it is referenced using a static global variable which is initialized once for all during probing and nullified at virtio device removal. Add proper SMP barriers to protect accesses to such device reference to ensure that the initialzation state of such device is correctly observed by all PEs at any time. Return -EBUSY, instead of -EINVAL, and a descriptive error message if more than one SCMI Virtio device is ever found and probed. Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- drivers/firmware/arm_scmi/virtio.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)