From: Julian Wiedmann <jwi@linux.ibm.com>
Date: Mon, 25 Nov 2019 14:18:29 +0100
Subject: s390/qdio: simplify ACK tracking
Git-commit: 0b6f499022b6a87d04f56edd2bf863ea76923206
Patch-mainline: v5.6-rc2
References: jsc#SLE-13690

Current code uses a 'polling' flag to keep track of whether an Input
Queue has any ACKed SBALs. QEBSM devices might have multiple ACKed
SBALs, and those are tracked separately with 'ack_count'.

By also setting ack_count for non-QEBSM devices (to a fixed value of 1),
we can use 'ack_count != 0' as replacement for the polling flag.

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.h       |    4 +---
 drivers/s390/cio/qdio_debug.c |    5 ++---
 drivers/s390/cio/qdio_main.c  |   29 +++++++++++------------------
 3 files changed, 14 insertions(+), 24 deletions(-)

--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -182,11 +182,9 @@ enum qdio_queue_irq_states {
 };
 
 struct qdio_input_q {
-	/* input buffer acknowledgement flag */
-	int polling;
 	/* first ACK'ed buffer */
 	int ack_start;
-	/* how much sbals are acknowledged with qebsm */
+	/* how many SBALs are acknowledged */
 	int ack_count;
 	/* last time of noticing incoming data */
 	u64 timestamp;
--- a/drivers/s390/cio/qdio_debug.c
+++ b/drivers/s390/cio/qdio_debug.c
@@ -124,9 +124,8 @@ static int qstat_show(struct seq_file *m
 	seq_printf(m, "nr_used: %d  ftc: %d\n",
 		   atomic_read(&q->nr_buf_used), q->first_to_check);
 	if (q->is_input_q) {
-		seq_printf(m, "polling: %d  ack start: %d  ack count: %d\n",
-			   q->u.in.polling, q->u.in.ack_start,
-			   q->u.in.ack_count);
+		seq_printf(m, "ack start: %d  ack count: %d\n",
+			   q->u.in.ack_start, q->u.in.ack_count);
 		seq_printf(m, "DSCI: %x   IRQs disabled: %u\n",
 			   *(u8 *)q->irq_ptr->dsci,
 			   test_bit(QDIO_QUEUE_IRQS_DISABLED,
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -393,19 +393,15 @@ int debug_get_buf_state(struct qdio_q *q
 
 static inline void qdio_stop_polling(struct qdio_q *q)
 {
-	if (!q->u.in.polling)
+	if (!q->u.in.ack_count)
 		return;
 
-	q->u.in.polling = 0;
 	qperf_inc(q, stop_polling);
 
 	/* show the card that we are not polling anymore */
-	if (is_qebsm(q)) {
-		set_buf_states(q, q->u.in.ack_start, SLSB_P_INPUT_NOT_INIT,
-			       q->u.in.ack_count);
-		q->u.in.ack_count = 0;
-	} else
-		set_buf_state(q, q->u.in.ack_start, SLSB_P_INPUT_NOT_INIT);
+	set_buf_states(q, q->u.in.ack_start, SLSB_P_INPUT_NOT_INIT,
+		       q->u.in.ack_count);
+	q->u.in.ack_count = 0;
 }
 
 static inline void account_sbals(struct qdio_q *q, unsigned int count)
@@ -451,8 +447,7 @@ static inline void inbound_primed(struct
 
 	/* for QEBSM the ACK was already set by EQBS */
 	if (is_qebsm(q)) {
-		if (!q->u.in.polling) {
-			q->u.in.polling = 1;
+		if (!q->u.in.ack_count) {
 			q->u.in.ack_count = count;
 			q->u.in.ack_start = start;
 			return;
@@ -471,12 +466,12 @@ static inline void inbound_primed(struct
 	 * or by the next inbound run.
 	 */
 	new = add_buf(start, count - 1);
-	if (q->u.in.polling) {
+	if (q->u.in.ack_count) {
 		/* reset the previous ACK but first set the new one */
 		set_buf_state(q, new, SLSB_P_INPUT_ACK);
 		set_buf_state(q, q->u.in.ack_start, SLSB_P_INPUT_NOT_INIT);
 	} else {
-		q->u.in.polling = 1;
+		q->u.in.ack_count = 1;
 		set_buf_state(q, new, SLSB_P_INPUT_ACK);
 	}
 
@@ -1479,13 +1474,12 @@ static int handle_inbound(struct qdio_q
 
 	qperf_inc(q, inbound_call);
 
-	if (!q->u.in.polling)
+	if (!q->u.in.ack_count)
 		goto set;
 
 	/* protect against stop polling setting an ACK for an emptied slsb */
 	if (count == QDIO_MAX_BUFFERS_PER_Q) {
 		/* overwriting everything, just delete polling status */
-		q->u.in.polling = 0;
 		q->u.in.ack_count = 0;
 		goto set;
 	} else if (buf_in_between(q->u.in.ack_start, bufnr, count)) {
@@ -1495,15 +1489,14 @@ static int handle_inbound(struct qdio_q
 			diff = sub_buf(diff, q->u.in.ack_start);
 			q->u.in.ack_count -= diff;
 			if (q->u.in.ack_count <= 0) {
-				q->u.in.polling = 0;
 				q->u.in.ack_count = 0;
 				goto set;
 			}
 			q->u.in.ack_start = add_buf(q->u.in.ack_start, diff);
+		} else {
+			/* the only ACK will be deleted */
+			q->u.in.ack_count = 0;
 		}
-		else
-			/* the only ACK will be deleted, so stop polling */
-			q->u.in.polling = 0;
 	}
 
 set: