[S390] qdio: EQBS retry after CCQ 96

Running under z/VM with QIOASSIST enabled, qdio queues could stall if EQBS
did not extract all SBAL states. Add an instant retry for EQBS and, if the
retry fails, set up a timer to ensure outstanding SBALs are processed later.

While at it, optimize qdio_do_eqbs and qdio_do_sqbs to eliminate 3 jumps on
the hot path.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/qdio_main.c

@@ -104,9 +104,12 @@ static inline int qdio_check_ccq(struct qdio_q *q, unsigned int ccq)
 	/* all done or next buffer state different */
 	if (ccq == 0 || ccq == 32)
 		return 0;
-	/* not all buffers processed */
-	if (ccq == 96 || ccq == 97)
+	/* no buffer processed */
+	if (ccq == 97)
 		return 1;
+	/* not all buffers processed */
+	if (ccq == 96)
+		return 2;
 	/* notify devices immediately */
 	DBF_ERROR("%4x ccq:%3d", SCH_NO(q), ccq);
 	return -EIO;
@@ -126,10 +129,8 @@ static inline int qdio_check_ccq(struct qdio_q *q, unsigned int ccq)
 static int qdio_do_eqbs(struct qdio_q *q, unsigned char *state,
 			int start, int count, int auto_ack)
 {
+	int rc, tmp_count = count, tmp_start = start, nr = q->nr, retried = 0;
 	unsigned int ccq = 0;
-	int tmp_count = count, tmp_start = start;
-	int nr = q->nr;
-	int rc;
 
 	BUG_ON(!q->irq_ptr->sch_token);
 	qperf_inc(q, eqbs);
@@ -140,30 +141,34 @@ static int qdio_do_eqbs(struct qdio_q *q, unsigned char *state,
 	ccq = do_eqbs(q->irq_ptr->sch_token, state, nr, &tmp_start, &tmp_count,
 		      auto_ack);
 	rc = qdio_check_ccq(q, ccq);
-
-	/* At least one buffer was processed, return and extract the remaining
-	 * buffers later.
-	 */
-	if ((ccq == 96) && (count != tmp_count)) {
-		qperf_inc(q, eqbs_partial);
-		return (count - tmp_count);
-	}
+	if (!rc)
+		return count - tmp_count;
 
 	if (rc == 1) {
 		DBF_DEV_EVENT(DBF_WARN, q->irq_ptr, "EQBS again:%2d", ccq);
 		goto again;
 	}
 
-	if (rc < 0) {
-		DBF_ERROR("%4x EQBS ERROR", SCH_NO(q));
-		DBF_ERROR("%3d%3d%2d", count, tmp_count, nr);
-		q->handler(q->irq_ptr->cdev,
-			   QDIO_ERROR_ACTIVATE_CHECK_CONDITION,
-			   q->nr, q->first_to_kick, count,
-			   q->irq_ptr->int_parm);
-		return 0;
+	if (rc == 2) {
+		BUG_ON(tmp_count == count);
+		qperf_inc(q, eqbs_partial);
+		DBF_DEV_EVENT(DBF_WARN, q->irq_ptr, "EQBS part:%02x",
+			tmp_count);
+		/*
+		 * Retry once, if that fails bail out and process the
+		 * extracted buffers before trying again.
+		 */
+		if (!retried++)
+			goto again;
+		else
+			return count - tmp_count;
 	}
-	return count - tmp_count;
+
+	DBF_ERROR("%4x EQBS ERROR", SCH_NO(q));
+	DBF_ERROR("%3d%3d%2d", count, tmp_count, nr);
+	q->handler(q->irq_ptr->cdev, QDIO_ERROR_ACTIVATE_CHECK_CONDITION,
+		   0, -1, -1, q->irq_ptr->int_parm);
+	return 0;
 }
 
 /**
@@ -196,22 +201,22 @@ static int qdio_do_sqbs(struct qdio_q *q, unsigned char state, int start,
 again:
 	ccq = do_sqbs(q->irq_ptr->sch_token, state, nr, &tmp_start, &tmp_count);
 	rc = qdio_check_ccq(q, ccq);
-	if (rc == 1) {
+	if (!rc) {
+		WARN_ON(tmp_count);
+		return count - tmp_count;
+	}
+
+	if (rc == 1 || rc == 2) {
 		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "SQBS again:%2d", ccq);
 		qperf_inc(q, sqbs_partial);
 		goto again;
 	}
-	if (rc < 0) {
-		DBF_ERROR("%4x SQBS ERROR", SCH_NO(q));
-		DBF_ERROR("%3d%3d%2d", count, tmp_count, nr);
-		q->handler(q->irq_ptr->cdev,
-			   QDIO_ERROR_ACTIVATE_CHECK_CONDITION,
-			   q->nr, q->first_to_kick, count,
-			   q->irq_ptr->int_parm);
-		return 0;
-	}
-	WARN_ON(tmp_count);
-	return count - tmp_count;
+
+	DBF_ERROR("%4x SQBS ERROR", SCH_NO(q));
+	DBF_ERROR("%3d%3d%2d", count, tmp_count, nr);
+	q->handler(q->irq_ptr->cdev, QDIO_ERROR_ACTIVATE_CHECK_CONDITION,
+		   0, -1, -1, q->irq_ptr->int_parm);
+	return 0;
 }
 
 /* returns number of examined buffers and their common state in *state */
@@ -915,10 +920,6 @@ static void __qdio_outbound_processing(struct qdio_q *q)
 		if (!pci_out_supported(q) && !qdio_outbound_q_done(q))
 			goto sched;
 
-	/* bail out for HiperSockets unicast queues */
-	if (queue_type(q) == QDIO_IQDIO_QFMT && !multicast_outbound(q))
-		return;
-
 	if ((queue_type(q) == QDIO_IQDIO_QFMT) &&
 	    (atomic_read(&q->nr_buf_used)) > QDIO_IQDIO_POLL_LVL)
 		goto sched;
@@ -928,8 +929,8 @@ static void __qdio_outbound_processing(struct qdio_q *q)
 
 	/*
 	 * Now we know that queue type is either qeth without pci enabled
-	 * or HiperSockets multicast. Make sure buffer switch from PRIMED to
-	 * EMPTY is noticed and outbound_handler is called after some time.
+	 * or HiperSockets. Make sure buffer switch from PRIMED to EMPTY
+	 * is noticed and outbound_handler is called after some time.
 	 */
 	if (qdio_outbound_q_done(q))
 		del_timer(&q->u.out.timer);