s390/qdio: extend polling support to multiple queues

When the support for polling drivers was initially added, it only
considered Input Queue 0. But as QDIO interrupts are actually for the
full device and not a single queue, this doesn't really fit for
configurations where multiple Input Queues are used.

Rework the qdio code so that interrupts for a polling driver are not
split up into actions for each queue. Instead deliver the interrupt as
a single event, and let the driver decide which queue needs what action.

When re-enabling the QDIO interrupt via qdio_start_irq(), this means
that the qdio code needs to
(1) put _all_ eligible queues back into a state where they raise IRQs,
(2) and afterwards check _all_ eligible queues for new work to bridge
    the race window.

On the qeth side of things (as the only qdio polling driver), we can now
add CQ polling support to the main NAPI poll routine. It doesn't consume
NAPI budget, and to avoid hogging the CPU we yield control after
completing one full queue worth of buffers.
The subsequent qdio_start_irq() will check for any additional work, and
have us re-schedule the NAPI instance accordingly.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 54 insertions, 65 deletions

diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h
index ff74eb5fce50..f72f961cc78f 100644
--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -177,8 +177,8 @@ struct qdio_queue_perf_stat {
 	unsigned int nr_sbal_total;
 };
 
-enum qdio_queue_irq_states {
-	QDIO_QUEUE_IRQS_DISABLED,
+enum qdio_irq_poll_states {
+	QDIO_IRQ_DISABLED,
 };
 
 struct qdio_input_q {
@@ -188,10 +188,6 @@ struct qdio_input_q {
 	int ack_count;
 	/* last time of noticing incoming data */
 	u64 timestamp;
-	/* upper-layer polling flag */
-	unsigned long queue_irq_state;
-	/* callback to start upper-layer polling */
-	void (*queue_start_poll) (struct ccw_device *, int, unsigned long);
 };
 
 struct qdio_output_q {
@@ -299,6 +295,9 @@ struct qdio_irq {
 	struct qdio_q *input_qs[QDIO_MAX_QUEUES_PER_IRQ];
 	struct qdio_q *output_qs[QDIO_MAX_QUEUES_PER_IRQ];
 
+	void (*irq_poll)(struct ccw_device *cdev, unsigned long data);
+	unsigned long poll_state;
+
 	debug_info_t *debug_area;
 	struct mutex setup_mutex;
 	struct qdio_dev_perf_stat perf_stat;
diff --git a/drivers/s390/cio/qdio_debug.c b/drivers/s390/cio/qdio_debug.c
index 9c0370b27426..00244607c8c0 100644
--- a/drivers/s390/cio/qdio_debug.c
+++ b/drivers/s390/cio/qdio_debug.c
@@ -128,8 +128,8 @@ static int qstat_show(struct seq_file *m, void *v)
 			   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,
-			   &q->u.in.queue_irq_state));
+			   test_bit(QDIO_IRQ_DISABLED,
+				    &q->irq_ptr->poll_state));
 	}
 	seq_printf(m, "SBAL states:\n");
 	seq_printf(m, "|0      |8      |16     |24     |32     |40     |48     |56  63|\n");
diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 3475317c42e5..02ced5949287 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -950,19 +950,14 @@ static void qdio_int_handler_pci(struct qdio_irq *irq_ptr)
 	if (unlikely(irq_ptr->state != QDIO_IRQ_STATE_ACTIVE))
 		return;
 
-	for_each_input_queue(irq_ptr, q, i) {
-		if (q->u.in.queue_start_poll) {
-			/* skip if polling is enabled or already in work */
-			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
-				     &q->u.in.queue_irq_state)) {
-				QDIO_PERF_STAT_INC(irq_ptr, int_discarded);
-				continue;
-			}
-			q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,
-						 q->irq_ptr->int_parm);
-		} else {
+	if (irq_ptr->irq_poll) {
+		if (!test_and_set_bit(QDIO_IRQ_DISABLED, &irq_ptr->poll_state))
+			irq_ptr->irq_poll(irq_ptr->cdev, irq_ptr->int_parm);
+		else
+			QDIO_PERF_STAT_INC(irq_ptr, int_discarded);
+	} else {
+		for_each_input_queue(irq_ptr, q, i)
 			tasklet_schedule(&q->tasklet);
-		}
 	}
 
 	if (!pci_out_supported(irq_ptr) || !irq_ptr->scan_threshold)
@@ -1610,24 +1605,26 @@ EXPORT_SYMBOL_GPL(do_QDIO);
 /**
  * qdio_start_irq - process input buffers
  * @cdev: associated ccw_device for the qdio subchannel
- * @nr: input queue number
  *
  * Return codes
  *   0 - success
  *   1 - irqs not started since new data is available
  */
-int qdio_start_irq(struct ccw_device *cdev, int nr)
+int qdio_start_irq(struct ccw_device *cdev)
 {
 	struct qdio_q *q;
 	struct qdio_irq *irq_ptr = cdev->private->qdio_data;
+	unsigned int i;
 
 	if (!irq_ptr)
 		return -ENODEV;
-	q = irq_ptr->input_qs[nr];
 
 	clear_nonshared_ind(irq_ptr);
-	qdio_stop_polling(q);
-	clear_bit(QDIO_QUEUE_IRQS_DISABLED, &q->u.in.queue_irq_state);
+
+	for_each_input_queue(irq_ptr, q, i)
+		qdio_stop_polling(q);
+
+	clear_bit(QDIO_IRQ_DISABLED, &irq_ptr->poll_state);
 
 	/*
 	 * We need to check again to not lose initiative after
@@ -1635,13 +1632,16 @@ int qdio_start_irq(struct ccw_device *cdev, int nr)
 	 */
 	if (test_nonshared_ind(irq_ptr))
 		goto rescan;
-	if (!qdio_inbound_q_done(q, q->first_to_check))
-		goto rescan;
+
+	for_each_input_queue(irq_ptr, q, i) {
+		if (!qdio_inbound_q_done(q, q->first_to_check))
+			goto rescan;
+	}
+
 	return 0;
 
 rescan:
-	if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
-			     &q->u.in.queue_irq_state))
+	if (test_and_set_bit(QDIO_IRQ_DISABLED, &irq_ptr->poll_state))
 		return 0;
 	else
 		return 1;
@@ -1729,23 +1729,19 @@ EXPORT_SYMBOL(qdio_get_next_buffers);
 /**
  * qdio_stop_irq - disable interrupt processing for the device
  * @cdev: associated ccw_device for the qdio subchannel
- * @nr: input queue number
  *
  * Return codes
  *   0 - interrupts were already disabled
  *   1 - interrupts successfully disabled
  */
-int qdio_stop_irq(struct ccw_device *cdev, int nr)
+int qdio_stop_irq(struct ccw_device *cdev)
 {
-	struct qdio_q *q;
 	struct qdio_irq *irq_ptr = cdev->private->qdio_data;
 
 	if (!irq_ptr)
 		return -ENODEV;
-	q = irq_ptr->input_qs[nr];
 
-	if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
-			     &q->u.in.queue_irq_state))
+	if (test_and_set_bit(QDIO_IRQ_DISABLED, &irq_ptr->poll_state))
 		return 0;
 	else
 		return 1;
diff --git a/drivers/s390/cio/qdio_setup.c b/drivers/s390/cio/qdio_setup.c
index 66e4bdca9d89..7b831bb4e229 100644
--- a/drivers/s390/cio/qdio_setup.c
+++ b/drivers/s390/cio/qdio_setup.c
@@ -224,15 +224,6 @@ static void setup_queues(struct qdio_irq *irq_ptr,
 		setup_queues_misc(q, irq_ptr, qdio_init->input_handler, i);
 
 		q->is_input_q = 1;
-		if (qdio_init->queue_start_poll_array &&
-		    qdio_init->queue_start_poll_array[i]) {
-			q->u.in.queue_start_poll =
-				qdio_init->queue_start_poll_array[i];
-			set_bit(QDIO_QUEUE_IRQS_DISABLED,
-				&q->u.in.queue_irq_state);
-		} else {
-			q->u.in.queue_start_poll = NULL;
-		}
 
 		setup_storage_lists(q, irq_ptr, input_sbal_array, i);
 		input_sbal_array += QDIO_MAX_BUFFERS_PER_Q;
@@ -483,6 +474,13 @@ int qdio_setup_irq(struct qdio_initialize *init_data)
 	ccw_device_get_schid(irq_ptr->cdev, &irq_ptr->schid);
 	setup_queues(irq_ptr, init_data);
 
+	if (init_data->irq_poll) {
+		irq_ptr->irq_poll = init_data->irq_poll;
+		set_bit(QDIO_IRQ_DISABLED, &irq_ptr->poll_state);
+	} else {
+		irq_ptr->irq_poll = NULL;
+	}
+
 	setup_qib(irq_ptr, init_data);
 	qdio_setup_thinint(irq_ptr);
 	set_impl_params(irq_ptr, init_data->qib_param_field_format,
diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c
index 7c4e4ec08a12..8f315c53de23 100644
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -135,28 +135,24 @@ static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
 	    has_multiple_inq_on_dsci(irq))
 		xchg(irq->dsci, 0);
 
+	if (irq->irq_poll) {
+		if (!test_and_set_bit(QDIO_IRQ_DISABLED, &irq->poll_state))
+			irq->irq_poll(irq->cdev, irq->int_parm);
+		else
+			QDIO_PERF_STAT_INC(irq, int_discarded);
+
+		return;
+	}
+
 	for_each_input_queue(irq, q, i) {
-		if (q->u.in.queue_start_poll) {
-			/* skip if polling is enabled or already in work */
-			if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
-					     &q->u.in.queue_irq_state)) {
-				QDIO_PERF_STAT_INC(irq, int_discarded);
-				continue;
-			}
-
-			/* avoid dsci clear here, done after processing */
-			q->u.in.queue_start_poll(irq->cdev, q->nr,
-						 irq->int_parm);
-		} else {
-			if (!shared_ind(irq))
-				xchg(irq->dsci, 0);
-
-			/*
-			 * Call inbound processing but not directly
-			 * since that could starve other thinint queues.
-			 */
-			tasklet_schedule(&q->tasklet);
-		}
+		if (!shared_ind(irq))
+			xchg(irq->dsci, 0);
+
+		/*
+		 * Call inbound processing but not directly
+		 * since that could starve other thinint queues.
+		 */
+		tasklet_schedule(&q->tasklet);
 	}
 }