From: Julian Wiedmann <jwi@linux.ibm.com>
Date: Fri, 4 Oct 2019 11:07:13 +0200
Subject: s390/qdio: don't attempt IRQ avoidance on Output SBALs
Git-commit: 6d76c898d82d94d066d870ba0180ec79bd3ceea5
Patch-mainline: v5.5-rc1
References: jsc#SLE-13690

Output interrupts are not subject to SLSB-based avoidance, so remove the
gratuitous SLSB updates for Output SBALs in ERROR state.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@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 |   17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -423,9 +423,6 @@ static inline void account_sbals(struct
 static void process_buffer_error(struct qdio_q *q, unsigned int start,
 				 int count)
 {
-	unsigned char state = (q->is_input_q) ? SLSB_P_INPUT_NOT_INIT :
-					SLSB_P_OUTPUT_NOT_INIT;
-
 	q->qdio_error = QDIO_ERROR_SLSB_STATE;
 
 	/* special handling for no target buffer empty */
@@ -433,7 +430,7 @@ static void process_buffer_error(struct
 	    q->sbal[start]->element[15].sflags == 0x10) {
 		qperf_inc(q, target_full);
 		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "OUTFULL FTC:%02x", start);
-		goto set;
+		return;
 	}
 
 	DBF_ERROR("%4x BUF ERROR", SCH_NO(q));
@@ -442,13 +439,6 @@ static void process_buffer_error(struct
 	DBF_ERROR("F14:%2x F15:%2x",
 		  q->sbal[start]->element[14].sflags,
 		  q->sbal[start]->element[15].sflags);
-
-set:
-	/*
-	 * Interrupts may be avoided as long as the error is present
-	 * so change the buffer state immediately to avoid starvation.
-	 */
-	set_buf_states(q, start, state, count);
 }
 
 static inline void inbound_primed(struct qdio_q *q, unsigned int start,
@@ -530,6 +520,11 @@ static int get_inbound_buffer_frontier(s
 		return count;
 	case SLSB_P_INPUT_ERROR:
 		process_buffer_error(q, start, count);
+		/*
+		 * Interrupts may be avoided as long as the error is present
+		 * so change the buffer state immediately to avoid starvation.
+		 */
+		set_buf_states(q, start, SLSB_P_INPUT_NOT_INIT, count);
 		if (atomic_sub_return(count, &q->nr_buf_used) == 0)
 			qperf_inc(q, inbound_queue_full);
 		if (q->irq_ptr->perf_stat_enabled)