Re: [PATCH v3 06/18] ibmvfc: add handlers to drain and complete Sub-CRQ responses

Brian King
2020-12-04T14:52:46Z

On 12/2/20 8:07 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@linux.ibm.com>
> ---
> drivers/scsi/ibmvscsi/ibmvfc.c | 80 ++++++++++++++++++++++++++++++++++
> 1 file changed, 80 insertions(+)
>
> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
> index e082935f56cf..b61ae1df21e5 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc.c
> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c
> @@ -3381,6 +3381,86 @@ 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;
> + }
> +
> + del_timer(&evt->timer);
> + list_del(&evt->queue);
> + ibmvfc_trc_end(evt);> + spin_unlock_irqrestore(vhost->host->host_lock, flags);

You can't do this here... You are grabbing the host lock in ibmvfc_drain_sub_crq
and saving the irqflags to a local in that function, then doing a spin_unlock_irqrestore
and restoring irqflags using an uninitialized local in this function...

I'm assuming this will get sorted out with the locking changes we've been discussing off-list...

> + evt->done(evt);
> + spin_lock_irqsave(vhost->host->host_lock, flags);
> +}
> +
> +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)
> + scrq->cur = 0;
> + rmb();
> + } else
> + crq = NULL;
> +
> + return crq;
> +}
> +
> +static void ibmvfc_drain_sub_crq(struct ibmvfc_sub_queue *scrq)
> +{
> + struct ibmvfc_crq *crq;
> + unsigned long flags;
> + int done = 0;
> +
> + spin_lock_irqsave(scrq->vhost->host->host_lock, flags);
> + while (!done) {
> + while ((crq = ibmvfc_next_scrq(scrq)) != NULL) {
> + ibmvfc_handle_scrq(crq, scrq->vhost);
> + crq->valid = 0;
> + wmb();
> + }
> +
> + ibmvfc_toggle_scrq_irq(scrq, 1);
> + if ((crq = ibmvfc_next_scrq(scrq)) != NULL) {
> + ibmvfc_toggle_scrq_irq(scrq, 0);
> + ibmvfc_handle_scrq(crq, scrq->vhost);
> + crq->valid = 0;
> + wmb();
> + } else
> + done = 1;
> + }
> + spin_unlock_irqrestore(scrq->vhost->host->host_lock, flags);
> +}
> +
> /**
> * ibmvfc_init_tgt - Set the next init job step for the target
> * @tgt: ibmvfc target struct
>

--
Brian King
Power Linux I/O
IBM Linux Technology Center