Hi,
On 6/29/22 19:43, Mathieu Poirier wrote:
> Hi Anup,
>
> On Wed, Jun 08, 2022 at 10:43:34PM +0530, Anup Patel wrote:
>> The rpmsg_probe() is broken at the moment because virtqueue_add_inbuf()
>> fails due to both virtqueues (Rx and Tx) marked as broken by the
>> __vring_new_virtqueue() function. To solve this, virtio_device_ready()
>> (which unbreaks queues) should be called before virtqueue_add_inbuf().
>>
>> Fixes: 8b4ec69d7e09 ("virtio: harden vring IRQ")
>> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
>> ---
>> drivers/rpmsg/virtio_rpmsg_bus.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
>> index 905ac7910c98..71a64d2c7644 100644
>> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
>> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
>> @@ -929,6 +929,9 @@ static int rpmsg_probe(struct virtio_device *vdev)
>> /* and half is dedicated for TX */
>> vrp->sbufs = bufs_va + total_buf_space / 2;
>>
>> + /* From this point on, we can notify and get callbacks. */
>> + virtio_device_ready(vdev);
>> +
>
> Calling virtio_device_ready() here means that virtqueue_get_buf_ctx_split() can
> potentially be called (by way of rpmsg_recv_done()), which will race with
> virtqueue_add_inbuf(). If buffers in the virtqueue aren't available then
> rpmsg_recv_done() will fail, potentially breaking remote processors' state
> machines that don't expect their initial name service to fail when the "device"
> has been marked as ready.
>
> What does make me curious though is that nobody on the remoteproc mailing list
> has complained about commit 8b4ec69d7e09 breaking their environment... By now,
> i.e rc4, that should have happened. Anyone from TI, ST and Xilinx care to test this on
> their rig?
I tested on STm32mp1 board using tag v5.19-rc4(03c765b0e3b4)
I confirm the issue!
Concerning the solution, I share Mathieu's concern. This could break legacy.
I made a short test and I would suggest to use __virtio_unbreak_device instead, tounbreak the virtqueues without changing the init sequence.
I this case the patch would be:
+ /*
+ * Unbreak the virtqueues to allow to add buffers before setting the vdev status
+ * to ready
+ */
+ __virtio_unbreak_device(vdev);
+
/* set up the receive buffers */
for (i = 0; i < vrp->num_bufs / 2; i++) {
struct scatterlist sg;
void *cpu_addr = vrp->rbufs + i * vrp->buf_size;
Regards,
Arnaud
>
> Thanks,
> Mathieu
>
>> /* set up the receive buffers */
>> for (i = 0; i < vrp->num_bufs / 2; i++) {
>> struct scatterlist sg;
>> @@ -983,9 +986,6 @@ static int rpmsg_probe(struct virtio_device *vdev)
>> */
>> notify = virtqueue_kick_prepare(vrp->rvq);
>>
>> - /* From this point on, we can notify and get callbacks. */
>> - virtio_device_ready(vdev);
>> -
>> /* tell the remote processor it can start sending messages */
>> /*
>> * this might be concurrent with callbacks, but we are only
>> --
>> 2.34.1
>>
