From: Julian Wiedmann <jwi@linux.ibm.com>
Date: Tue, 2 Jun 2020 14:26:36 +0200
Subject: s390/qdio: warn about unexpected SLSB states
Git-commit: c920c545286270302d29fd63c05c3bd84828daee
Patch-mainline: v5.8-rc2
References: jsc#SLE-13690

The way we produce SBALs to the device (first update q->nr_buf_used,
then update the SLSB) should ensure that we never see some of the
SLSB states when scanning the queue for progress.
So make some noise if we do, this implies a bug in our SBAL tracking.

Also tweak the WARN msg to provide more information.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/cio/qdio_main.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index f42129c02927..0c919a11a46e 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -503,15 +503,18 @@ static int get_inbound_buffer_frontier(struct qdio_q *q, unsigned int start)
 			account_sbals_error(q, count);
 		return count;
 	case SLSB_CU_INPUT_EMPTY:
-	case SLSB_P_INPUT_NOT_INIT:
-	case SLSB_P_INPUT_ACK:
 		if (q->irq_ptr->perf_stat_enabled)
 			q->q_stats.nr_sbal_nop++;
 		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "in nop:%1d %#02x",
 			      q->nr, start);
 		return 0;
+	case SLSB_P_INPUT_NOT_INIT:
+	case SLSB_P_INPUT_ACK:
+		/* We should never see this state, throw a WARN: */
 	default:
-		WARN_ON_ONCE(1);
+		dev_WARN_ONCE(&q->irq_ptr->cdev->dev, 1,
+			      "found state %#x at index %u on queue %u\n",
+			      state, start, q->nr);
 		return 0;
 	}
 }
@@ -716,11 +719,14 @@ static int get_outbound_buffer_frontier(struct qdio_q *q, unsigned int start)
 		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "out primed:%1d",
 			      q->nr);
 		return 0;
-	case SLSB_P_OUTPUT_NOT_INIT:
 	case SLSB_P_OUTPUT_HALTED:
 		return 0;
+	case SLSB_P_OUTPUT_NOT_INIT:
+		/* We should never see this state, throw a WARN: */
 	default:
-		WARN_ON_ONCE(1);
+		dev_WARN_ONCE(&q->irq_ptr->cdev->dev, 1,
+			      "found state %#x at index %u on queue %u\n",
+			      state, start, q->nr);
 		return 0;
 	}
 }