On 12/1/20 6:53 PM, Tyrel Datwyler wrote:

+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);

Another thought here... If you are going through ibmvfc_purge_requests at the same time
as this code, you could check the free bit above, then have ibmvfc_purge_requests
put the event on the free queue and call scsi_done, then you come down and get the host
lock here, remove the command from the free list, and call the done function again,
which could result in a double completion to the scsi layer.

I think you need to grab the host lock before you check the free bit to avoid this race.

+	spin_unlock_irqrestore(vhost->host->host_lock, flags);
+	evt->done(evt);
+}
+

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