Commit 0a6e6345 authored by Julian Wiedmann's avatar Julian Wiedmann Committed by David S. Miller
Browse files

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: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Acked-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b439044b

arch/s390/include/asm/qdio.h

+4 −5
Original line number Diff line number Diff line
@@ -338,7 +338,7 @@ typedef void qdio_handler_t(struct ccw_device *, unsigned int, int, 
 * @no_output_qs: number of output queues

 * @input_handler: handler to be called for input queues

 * @output_handler: handler to be called for output queues

 * @queue_start_poll_array: polling handlers (one per input queue or NULL)

 * @irq_poll: Data IRQ polling handler (NULL when not supported)

 * @scan_threshold: # of in-use buffers that triggers scan on output queue

 * @int_parm: interruption parameter

 * @input_sbal_addr_array:  address of no_input_qs * 128 pointers
@@ -359,8 +359,7 @@ struct qdio_initialize { 
	unsigned int no_output_qs;

	qdio_handler_t *input_handler;

	qdio_handler_t *output_handler;

	void (**queue_start_poll_array) (struct ccw_device *, int,

					  unsigned long);

	void (*irq_poll)(struct ccw_device *cdev, unsigned long data);

	unsigned int scan_threshold;

	unsigned long int_parm;

	struct qdio_buffer **input_sbal_addr_array;
@@ -415,8 +414,8 @@ extern int qdio_activate(struct ccw_device *); 
extern void qdio_release_aob(struct qaob *);

extern int do_QDIO(struct ccw_device *, unsigned int, int, unsigned int,

		   unsigned int);

extern int qdio_start_irq(struct ccw_device *, int);

extern int qdio_stop_irq(struct ccw_device *, int);

extern int qdio_start_irq(struct ccw_device *cdev);

extern int qdio_stop_irq(struct ccw_device *cdev);

extern int qdio_get_next_buffers(struct ccw_device *, int, int *, int *);

extern int qdio_inspect_queue(struct ccw_device *cdev, unsigned int nr,

			      bool is_input, unsigned int *bufnr,

drivers/s390/cio/qdio.h

+5 −6
Original line number Diff line number Diff line
@@ -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;

drivers/s390/cio/qdio_debug.c

+2 −2
Original line number Diff line number Diff line
@@ -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");

drivers/s390/cio/qdio_main.c

+23 −27
Original line number Diff line number Diff line
@@ -950,20 +950,15 @@ 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)) {

	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);

				continue;

			}

			q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,

						 q->irq_ptr->int_parm);

	} else {

		for_each_input_queue(irq_ptr, q, i)

			tasklet_schedule(&q->tasklet);

	}

	}



	if (!pci_out_supported(irq_ptr) || !irq_ptr->scan_threshold)

		return;
@@ -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);



	for_each_input_queue(irq_ptr, q, i)

		qdio_stop_polling(q);

	clear_bit(QDIO_QUEUE_IRQS_DISABLED, &q->u.in.queue_irq_state);



	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;



	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;

drivers/s390/cio/qdio_setup.c

+7 −9
Original line number Diff line number Diff line
@@ -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,

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