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 <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 48 insertions, 36 deletions

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index 3d54c8bbfa86..ecfd6d152e86 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -764,6 +764,7 @@ struct qeth_rx {
 	u8 buf_element;
 	int e_offset;
 	int qdio_err;
+	u8 bufs_refill;
 };
 
 struct carrier_info {
@@ -833,7 +834,6 @@ struct qeth_card {
 	struct napi_struct napi;
 	struct qeth_rx rx;
 	struct delayed_work buffer_reclaim_work;
-	int reclaim_index;
 	struct work_struct close_dev_work;
 };
 
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 8a76022fceda..bba1b54b8aa3 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -204,12 +204,17 @@ EXPORT_SYMBOL_GPL(qeth_threads_running);
 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);
 
@@ -2965,7 +2970,7 @@ static struct qeth_buffer_pool_entry *qeth_find_free_buffer_pool_entry(
 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)) {
@@ -2976,9 +2981,13 @@ static int qeth_init_input_buffer(struct qeth_card *card,
 			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
@@ -2986,8 +2995,6 @@ static int qeth_init_input_buffer(struct qeth_card *card,
 	 * 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 =
@@ -3015,6 +3022,7 @@ static unsigned int qeth_tx_select_bulk_max(struct qeth_card *card,
 
 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;
 
@@ -3026,16 +3034,14 @@ static int qeth_init_qdio_queues(struct qeth_card *card)
 
 	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;
@@ -3485,20 +3491,15 @@ static int qeth_check_qdio_errors(struct qeth_card *card,
 	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;
@@ -3526,21 +3527,13 @@ static void qeth_queue_input_buffer(struct qeth_card *card, int index)
 				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) {
@@ -3548,7 +3541,10 @@ static void qeth_queue_input_buffer(struct qeth_card *card, int index)
 		}
 		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)
@@ -3556,8 +3552,10 @@ 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,
@@ -5736,6 +5734,7 @@ static unsigned int qeth_extract_skbs(struct qeth_card *card, int budget,
 
 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) {
@@ -5771,8 +5770,11 @@ static unsigned int qeth_rx_poll(struct qeth_card *card, int budget)
 		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);
@@ -5812,9 +5814,16 @@ int qeth_poll(struct napi_struct *napi, int budget)
 	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)))
@@ -7001,6 +7010,7 @@ int qeth_stop(struct net_device *dev)
 	}
 
 	napi_disable(&card->napi);
+	cancel_delayed_work_sync(&card->buffer_reclaim_work);
 	qdio_stop_irq(CARD_DDEV(card));
 
 	return 0;
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index ef7a2db7a724..8b342a88ff5c 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -285,7 +285,6 @@ static void qeth_l2_stop_card(struct qeth_card *card)
 	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;
 	}
 
@@ -1141,6 +1140,10 @@ static void qeth_bridge_state_change(struct qeth_card *card,
 	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;
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 15a12487ff7a..fe44b0249e34 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -1169,7 +1169,6 @@ static void qeth_l3_stop_card(struct qeth_card *card)
 		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;
 	}