On 12/1/20 6:53 PM, Tyrel Datwyler wrote:
> The logic for iterating over the Sub-CRQ responses is similiar to that
> of the primary CRQ. Add the necessary handlers for processing those
> responses.
>
> Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxx>
> ---
> drivers/scsi/ibmvscsi/ibmvfc.c | 77 ++++++++++++++++++++++++++++++++++
> 1 file changed, 77 insertions(+)
>
> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
> index 97f00fefa809..e9da3f60c793 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc.c
> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c
> @@ -3381,6 +3381,83 @@ static int ibmvfc_toggle_scrq_irq(struct ibmvfc_sub_queue *scrq, int enable)
> return rc;
> }
>
> +static void ibmvfc_handle_scrq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost)
> +{
> + struct ibmvfc_event *evt = (struct ibmvfc_event *)be64_to_cpu(crq->ioba);
> + unsigned long flags;
> +
> + switch (crq->valid) {
> + case IBMVFC_CRQ_CMD_RSP:
> + break;
> + case IBMVFC_CRQ_XPORT_EVENT:
> + return;
> + default:
> + dev_err(vhost->dev, "Got and invalid message type 0x%02x\n", crq->valid);
> + return;
> + }
> +
> + /* The only kind of payload CRQs we should get are responses to
> + * things we send. Make sure this response is to something we
> + * actually sent
> + */
> + if (unlikely(!ibmvfc_valid_event(&vhost->pool, evt))) {
> + dev_err(vhost->dev, "Returned correlation_token 0x%08llx is invalid!\n",
> + crq->ioba);
> + return;
> + }
> +
> + if (unlikely(atomic_read(&evt->free))) {
> + dev_err(vhost->dev, "Received duplicate correlation_token 0x%08llx!\n",
> + crq->ioba);
> + return;
> + }
> +
> + spin_lock_irqsave(vhost->host->host_lock, flags);
> + del_timer(&evt->timer);
> + list_del(&evt->queue);
> + ibmvfc_trc_end(evt);
> + spin_unlock_irqrestore(vhost->host->host_lock, flags);
> + evt->done(evt);
> +}
> +
> +static struct ibmvfc_crq *ibmvfc_next_scrq(struct ibmvfc_sub_queue *scrq)
> +{
> + struct ibmvfc_crq *crq;
> +
> + crq = &scrq->msgs[scrq->cur].crq;
> + if (crq->valid & 0x80) {
> + if (++scrq->cur == scrq->size)
You are incrementing the cur pointer without any locks held. Although
unlikely, could you also be in ibmvfc_reset_crq in another thread?
If so, you'd have a subtle race condition here where the cur pointer could
be read, then ibmvfc_reset_crq writes it to zero, then this thread
writes it to a non zero value, which would then cause you to be out of
sync with the VIOS as to where the cur pointer is.
> + scrq->cur = 0;
> + rmb();
> + } else
> + crq = NULL;
> +
> + return crq;
> +}
> +
--
Brian King
Power Linux I/O
IBM Linux Technology Center
