Merge branch 's390-qeth-next'

Julian Wiedmann says:

====================
s390/qeth: updates 2020-07-30

please apply the following patch series for qeth to netdev's net-next tree.

This primarily brings some modernization to the RX path, laying the
groundwork for smarter RX refill policies.
Some of the patches are tagged as fixes, but really target only rare /
theoretical issues. So given where we are in the release cycle and that we
touch the main RX path, taking them through net-next seems more appropriate.
====================

Reviewed-by: Jakub Kicinski <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/s390/net/qeth_core.h

···
 	u8 buf_element;
 	int e_offset;
 	int qdio_err;
+	u8 bufs_refill;
 };
 
 struct carrier_info {
···
 	struct napi_struct napi;
 	struct qeth_rx rx;
 	struct delayed_work buffer_reclaim_work;
-	int reclaim_index;
 	struct work_struct close_dev_work;
 };
 

drivers/s390/net/qeth_core_main.c

···
 void qeth_clear_working_pool_list(struct qeth_card *card)
 {
 	struct qeth_buffer_pool_entry *pool_entry, *tmp;
+	struct qeth_qdio_q *queue = card->qdio.in_q;
+	unsigned int i;
 
 	QETH_CARD_TEXT(card, 5, "clwrklst");
 	list_for_each_entry_safe(pool_entry, tmp,
 			    &card->qdio.in_buf_pool.entry_list, list){
 			list_del(&pool_entry->list);
 	}
+
+	for (i = 0; i < ARRAY_SIZE(queue->bufs); i++)
+		queue->bufs[i].pool_entry = NULL;
 }
 EXPORT_SYMBOL_GPL(qeth_clear_working_pool_list);
 
···
 static int qeth_init_input_buffer(struct qeth_card *card,
 		struct qeth_qdio_buffer *buf)
 {
-	struct qeth_buffer_pool_entry *pool_entry;
+	struct qeth_buffer_pool_entry *pool_entry = buf->pool_entry;
 	int i;
 
 	if ((card->options.cq == QETH_CQ_ENABLED) && (!buf->rx_skb)) {
···
 			return -ENOMEM;
 	}
 
-	pool_entry = qeth_find_free_buffer_pool_entry(card);
-	if (!pool_entry)
-		return -ENOBUFS;
+	if (!pool_entry) {
+		pool_entry = qeth_find_free_buffer_pool_entry(card);
+		if (!pool_entry)
+			return -ENOBUFS;
+
+		buf->pool_entry = pool_entry;
+	}
 
 	/*
 	 * since the buffer is accessed only from the input_tasklet
···
 	 * the QETH_IN_BUF_REQUEUE_THRESHOLD we should never run  out off
 	 * buffers
 	 */
-
-	buf->pool_entry = pool_entry;
 	for (i = 0; i < QETH_MAX_BUFFER_ELEMENTS(card); ++i) {
 		buf->buffer->element[i].length = PAGE_SIZE;
 		buf->buffer->element[i].addr =
···
 
 static int qeth_init_qdio_queues(struct qeth_card *card)
 {
+	unsigned int rx_bufs = card->qdio.in_buf_pool.buf_count;
 	unsigned int i;
 	int rc;
 
···
 
 	qeth_initialize_working_pool_list(card);
 	/*give only as many buffers to hardware as we have buffer pool entries*/
-	for (i = 0; i < card->qdio.in_buf_pool.buf_count - 1; i++) {
+	for (i = 0; i < rx_bufs; i++) {
 		rc = qeth_init_input_buffer(card, &card->qdio.in_q->bufs[i]);
 		if (rc)
 			return rc;
 	}
 
-	card->qdio.in_q->next_buf_to_init =
-		card->qdio.in_buf_pool.buf_count - 1;
-	rc = do_QDIO(CARD_DDEV(card), QDIO_FLAG_SYNC_INPUT, 0, 0,
-		     card->qdio.in_buf_pool.buf_count - 1);
+	card->qdio.in_q->next_buf_to_init = QDIO_BUFNR(rx_bufs);
+	rc = do_QDIO(CARD_DDEV(card), QDIO_FLAG_SYNC_INPUT, 0, 0, rx_bufs);
 	if (rc) {
 		QETH_CARD_TEXT_(card, 2, "1err%d", rc);
 		return rc;
···
 	return 0;
 }
 
-static void qeth_queue_input_buffer(struct qeth_card *card, int index)
+static unsigned int qeth_rx_refill_queue(struct qeth_card *card,
+					 unsigned int count)
 {
 	struct qeth_qdio_q *queue = card->qdio.in_q;
 	struct list_head *lh;
-	int count;
 	int i;
 	int rc;
 	int newcount = 0;
 
-	count = (index < queue->next_buf_to_init)?
-		card->qdio.in_buf_pool.buf_count -
-		(queue->next_buf_to_init - index) :
-		card->qdio.in_buf_pool.buf_count -
-		(queue->next_buf_to_init + QDIO_MAX_BUFFERS_PER_Q - index);
 	/* only requeue at a certain threshold to avoid SIGAs */
 	if (count >= QETH_IN_BUF_REQUEUE_THRESHOLD(card)) {
 		for (i = queue->next_buf_to_init;
···
 				i++;
 			if (i == card->qdio.in_buf_pool.buf_count) {
 				QETH_CARD_TEXT(card, 2, "qsarbw");
-				card->reclaim_index = index;
 				schedule_delayed_work(
 					&card->buffer_reclaim_work,
 					QETH_RECLAIM_WORK_TIME);
 			}
-			return;
+			return 0;
 		}
 
-		/*
-		 * according to old code it should be avoided to requeue all
-		 * 128 buffers in order to benefit from PCI avoidance.
-		 * this function keeps at least one buffer (the buffer at
-		 * 'index') un-requeued -> this buffer is the first buffer that
-		 * will be requeued the next time
-		 */
 		rc = do_QDIO(CARD_DDEV(card), QDIO_FLAG_SYNC_INPUT, 0,
 			     queue->next_buf_to_init, count);
 		if (rc) {
···
 		}
 		queue->next_buf_to_init = QDIO_BUFNR(queue->next_buf_to_init +
 						     count);
+		return count;
 	}
+
+	return 0;
 }
 
 static void qeth_buffer_reclaim_work(struct work_struct *work)
···
 	struct qeth_card *card = container_of(work, struct qeth_card,
 		buffer_reclaim_work.work);
 
-	QETH_CARD_TEXT_(card, 2, "brw:%x", card->reclaim_index);
-	qeth_queue_input_buffer(card, card->reclaim_index);
+	local_bh_disable();
+	napi_schedule(&card->napi);
+	/* kick-start the NAPI softirq: */
+	local_bh_enable();
 }
 
 static void qeth_handle_send_error(struct qeth_card *card,
···
 
 static unsigned int qeth_rx_poll(struct qeth_card *card, int budget)
 {
+	struct qeth_rx *ctx = &card->rx;
 	unsigned int work_done = 0;
 
 	while (budget > 0) {
···
 		if (done) {
 			QETH_CARD_STAT_INC(card, rx_bufs);
 			qeth_put_buffer_pool_entry(card, buffer->pool_entry);
-			qeth_queue_input_buffer(card, card->rx.b_index);
+			buffer->pool_entry = NULL;
 			card->rx.b_count--;
+			ctx->bufs_refill++;
+			ctx->bufs_refill -= qeth_rx_refill_queue(card,
+								 ctx->bufs_refill);
 
 			/* Step forward to next buffer: */
 			card->rx.b_index = QDIO_BUFNR(card->rx.b_index + 1);
···
 	if (card->options.cq == QETH_CQ_ENABLED)
 		qeth_cq_poll(card);
 
-	/* Exhausted the RX budget. Keep IRQ disabled, we get called again. */
-	if (budget && work_done >= budget)
-		return work_done;
+	if (budget) {
+		struct qeth_rx *ctx = &card->rx;
+
+		/* Process any substantial refill backlog: */
+		ctx->bufs_refill -= qeth_rx_refill_queue(card, ctx->bufs_refill);
+
+		/* Exhausted the RX budget. Keep IRQ disabled, we get called again. */
+		if (work_done >= budget)
+			return work_done;
+	}
 
 	if (napi_complete_done(napi, work_done) &&
 	    qdio_start_irq(CARD_DDEV(card)))
···
 	}
 
 	napi_disable(&card->napi);
+	cancel_delayed_work_sync(&card->buffer_reclaim_work);
 	qdio_stop_irq(CARD_DDEV(card));
 
 	return 0;

drivers/s390/net/qeth_l2_main.c

···
 	if (card->state == CARD_STATE_SOFTSETUP) {
 		qeth_clear_ipacmd_list(card);
 		qeth_drain_output_queues(card);
-		cancel_delayed_work_sync(&card->buffer_reclaim_work);
 		card->state = CARD_STATE_DOWN;
 	}
 
···
 	int extrasize;
 
 	QETH_CARD_TEXT(card, 2, "brstchng");
+	if (qports->num_entries == 0) {
+		QETH_CARD_TEXT(card, 2, "BPempty");
+		return;
+	}
 	if (qports->entry_length != sizeof(struct qeth_sbp_port_entry)) {
 		QETH_CARD_TEXT_(card, 2, "BPsz%04x", qports->entry_length);
 		return;

drivers/s390/net/qeth_l3_main.c

···
 		qeth_l3_clear_ip_htable(card, 1);
 		qeth_clear_ipacmd_list(card);
 		qeth_drain_output_queues(card);
-		cancel_delayed_work_sync(&card->buffer_reclaim_work);
 		card->state = CARD_STATE_DOWN;
 	}