Commit 2223318c authored by Julian Wiedmann's avatar Julian Wiedmann Committed by Vasily Gorbik
Browse files

s390/qdio: remove 'merge_pending' mechanism 



For non-QEBSM devices, get_buf_states() merges PENDING and EMPTY buffers
into a single group of finished buffers. To allow the upper-layer driver
to differentiate between the two states, qdio_check_pending() looks at
each buffer's state again and sets the sbal_state flag to
QDIO_OUTBUF_STATE_FLAG_PENDING accordingly.

So effectively we're spending overhead on _every_ Output Queue
inspection, just to avoid some additional TX completion calls in case
a group of buffers has completed with mixed EMPTY / PENDING state.
Given that PENDING buffers should rarely occur, this is a bad trade-off.
In particular so as the additional checks in get_buf_states() affect
_all_ device types (even those that don't use the PENDING state).

Rip it all out, and just report the PENDING completions separately as
we already do for QEBSM devices.

Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: default avatarBenjamin Block <bblock@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 7940eaf2

arch/s390/include/asm/qdio.h

+0 −4
Original line number Diff line number Diff line
@@ -250,17 +250,13 @@ struct slsb { 
 * struct qdio_outbuf_state - SBAL related asynchronous operation information

 *   (for communication with upper layer programs)

 *   (only required for use with completion queues)

 * @flags: flags indicating state of buffer

 * @user: pointer to upper layer program's state information related to SBAL

 *        (stored in user1 data of QAOB)

 */

struct qdio_outbuf_state {

	u8 flags;

	void *user;

};



#define QDIO_OUTBUF_STATE_FLAG_PENDING	0x01



#define CHSC_AC1_INITIATE_INPUTQ	0x80

drivers/s390/cio/qdio_main.c

+9 −50
Original line number Diff line number Diff line
@@ -202,7 +202,7 @@ static int qdio_do_sqbs(struct qdio_q *q, unsigned char state, int start, 
 */

static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr,

				 unsigned char *state, unsigned int count,

				 int auto_ack, int merge_pending)

				 int auto_ack)

{

	unsigned char __state = 0;

	int i = 1;
@@ -217,18 +217,9 @@ static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr, 
	if (__state & SLSB_OWNER_CU)

		goto out;



	if (merge_pending && __state == SLSB_P_OUTPUT_PENDING)

		__state = SLSB_P_OUTPUT_EMPTY;



	for (; i < count; i++) {

		bufnr = next_buf(bufnr);



		/* merge PENDING into EMPTY: */

		if (merge_pending &&

		    q->slsb.val[bufnr] == SLSB_P_OUTPUT_PENDING &&

		    __state == SLSB_P_OUTPUT_EMPTY)

			continue;



		/* stop if next state differs from initial state: */

		if (q->slsb.val[bufnr] != __state)

			break;
@@ -242,7 +233,7 @@ static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr, 
static inline int get_buf_state(struct qdio_q *q, unsigned int bufnr,

				unsigned char *state, int auto_ack)

{

	return get_buf_states(q, bufnr, state, 1, auto_ack, 0);

	return get_buf_states(q, bufnr, state, 1, auto_ack);

}



/* wrap-around safe setting of slsb states, returns number of changed buffers */
@@ -464,7 +455,7 @@ static int get_inbound_buffer_frontier(struct qdio_q *q, unsigned int start, 
	 * No siga sync here, as a PCI or we after a thin interrupt

	 * already sync'ed the queues.

	 */

	count = get_buf_states(q, start, &state, count, 1, 0);

	count = get_buf_states(q, start, &state, count, 1);

	if (!count)

		return 0;
@@ -541,7 +532,6 @@ static inline unsigned long qdio_aob_for_buffer(struct qdio_output_q *q, 
		WARN_ON_ONCE(phys_aob & 0xFF);

	}



	q->sbal_state[bufnr].flags = 0;

	return phys_aob;

}
@@ -554,19 +544,6 @@ static inline int qdio_tasklet_schedule(struct qdio_q *q) 
	return -EPERM;

}



static void qdio_check_pending(struct qdio_q *q, unsigned int index)

{

	unsigned char state;



	if (get_buf_state(q, index, &state, 0) > 0 &&

	    state == SLSB_P_OUTPUT_PENDING &&

	    q->u.out.aobs[index]) {

		q->u.out.sbal_state[index].flags |=

			QDIO_OUTBUF_STATE_FLAG_PENDING;

		q->u.out.aobs[index] = NULL;

	}

}



static int get_outbound_buffer_frontier(struct qdio_q *q, unsigned int start,

					unsigned int *error)

{
@@ -587,7 +564,7 @@ static int get_outbound_buffer_frontier(struct qdio_q *q, unsigned int start, 
	if (!count)

		return 0;



	count = get_buf_states(q, start, &state, count, 0, q->u.out.use_cq);

	count = get_buf_states(q, start, &state, count, 0);

	if (!count)

		return 0;
@@ -609,6 +586,9 @@ static int get_outbound_buffer_frontier(struct qdio_q *q, unsigned int start, 
			account_sbals(q, count);

		return count;

	case SLSB_P_OUTPUT_ERROR:

		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "out error:%1d %02x",

			      q->nr, count);



		*error = QDIO_ERROR_SLSB_STATE;

		process_buffer_error(q, start, count);

		atomic_sub(count, &q->nr_buf_used);
@@ -640,27 +620,6 @@ static inline int qdio_outbound_q_done(struct qdio_q *q) 
	return atomic_read(&q->nr_buf_used) == 0;

}



static inline int qdio_outbound_q_moved(struct qdio_q *q, unsigned int start,

					unsigned int *error)

{

	int count;



	count = get_outbound_buffer_frontier(q, start, error);



	if (count) {

		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "out moved:%1d", q->nr);



		if (q->u.out.use_cq && *error != QDIO_ERROR_SLSB_PENDING) {

			unsigned int i;



			for (i = 0; i < count; i++)

				qdio_check_pending(q, QDIO_BUFNR(start + i));

		}

	}



	return count;

}



static int qdio_kick_outbound_q(struct qdio_q *q, unsigned int count,

				unsigned long aob)

{
@@ -715,7 +674,7 @@ void qdio_outbound_tasklet(struct tasklet_struct *t) 
	qperf_inc(q, tasklet_outbound);

	WARN_ON_ONCE(atomic_read(&q->nr_buf_used) < 0);



	count = qdio_outbound_q_moved(q, start, &error);

	count = get_outbound_buffer_frontier(q, start, &error);

	if (count) {

		q->first_to_check = add_buf(start, count);
@@ -1482,7 +1441,7 @@ static int __qdio_inspect_queue(struct qdio_q *q, unsigned int *bufnr, 


	*error = 0;

	count = q->is_input_q ? get_inbound_buffer_frontier(q, start, error) :

				qdio_outbound_q_moved(q, start, error);

				get_outbound_buffer_frontier(q, start, error);

	if (count == 0)

		return 0;

drivers/s390/net/qeth_core_main.c

+1 −3
Original line number Diff line number Diff line
@@ -6076,9 +6076,7 @@ static void qeth_iqd_tx_complete(struct qeth_qdio_out_q *queue, 
	struct qeth_card *card = queue->card;

	bool error = !!qdio_error;



	if ((qdio_error == QDIO_ERROR_SLSB_PENDING) ||

	    (queue->bufstates && (queue->bufstates[bidx].flags &

				  QDIO_OUTBUF_STATE_FLAG_PENDING))) {

	if (qdio_error == QDIO_ERROR_SLSB_PENDING) {

		WARN_ON_ONCE(card->options.cq != QETH_CQ_ENABLED);



		QETH_CARD_TEXT_(card, 5, "pel%u", bidx);