[PATCH net 0/4] s390/qeth: fixes 2021-03-09

[PATCH net 0/4] s390/qeth: fixes 2021-03-09

[Julian Wiedmann]

Hi Dave & Jakub,

please apply the following patch series to netdev's net tree.

This brings one fix for a memleak in an error path of the setup code.
Also several fixes for dealing with pending TX buffers - two for old
bugs in their completion handling, and one recent regression in a
teardown path.

Thanks,
Julian

Julian Wiedmann (4):
  s390/qeth: fix memory leak after failed TX Buffer allocation
  s390/qeth: improve completion of pending TX buffers
  s390/qeth: schedule TX NAPI on QAOB completion
  s390/qeth: fix notification for pending buffers during teardown

 drivers/s390/net/qeth_core.h      |   3 +-
 drivers/s390/net/qeth_core_main.c | 128 ++++++++++++++----------------
 2 files changed, 62 insertions(+), 69 deletions(-)

-- 
2.25.1

[PATCH net 1/4] s390/qeth: fix memory leak after failed TX Buffer allocation

[Julian Wiedmann]

When qeth_alloc_qdio_queues() fails to allocate one of the buffers that
back an Output Queue, the 'out_freeoutqbufs' path will free all
previously allocated buffers for this queue. But it misses to free the
half-finished queue struct itself.

Move the buffer allocation into qeth_alloc_output_queue(), and deal with
such errors internally.

Fixes: 0da9581ddb0f ("qeth: exploit asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
---
 drivers/s390/net/qeth_core_main.c | 35 +++++++++++++++----------------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index b71b8902d1c4..f7bc0ca6909b 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2634,15 +2634,28 @@ static void qeth_free_output_queue(struct qeth_qdio_out_q *q)
 static struct qeth_qdio_out_q *qeth_alloc_output_queue(void)
 {
 	struct qeth_qdio_out_q *q = kzalloc(sizeof(*q), GFP_KERNEL);
+	unsigned int i;
 
 	if (!q)
 		return NULL;
 
-	if (qdio_alloc_buffers(q->qdio_bufs, QDIO_MAX_BUFFERS_PER_Q)) {
-		kfree(q);
-		return NULL;
+	if (qdio_alloc_buffers(q->qdio_bufs, QDIO_MAX_BUFFERS_PER_Q))
+		goto err_qdio_bufs;
+
+	for (i = 0; i < QDIO_MAX_BUFFERS_PER_Q; i++) {
+		if (qeth_init_qdio_out_buf(q, i))
+			goto err_out_bufs;
 	}
+
 	return q;
+
+err_out_bufs:
+	while (i > 0)
+		kmem_cache_free(qeth_qdio_outbuf_cache, q->bufs[--i]);
+	qdio_free_buffers(q->qdio_bufs, QDIO_MAX_BUFFERS_PER_Q);
+err_qdio_bufs:
+	kfree(q);
+	return NULL;
 }
 
 static void qeth_tx_completion_timer(struct timer_list *timer)
@@ -2655,7 +2668,7 @@ static void qeth_tx_completion_timer(struct timer_list *timer)
 
 static int qeth_alloc_qdio_queues(struct qeth_card *card)
 {
-	int i, j;
+	unsigned int i;
 
 	QETH_CARD_TEXT(card, 2, "allcqdbf");
 
@@ -2689,13 +2702,6 @@ static int qeth_alloc_qdio_queues(struct qeth_card *card)
 		queue->coalesce_usecs = QETH_TX_COALESCE_USECS;
 		queue->max_coalesced_frames = QETH_TX_MAX_COALESCED_FRAMES;
 		queue->priority = QETH_QIB_PQUE_PRIO_DEFAULT;
-
-		/* give outbound qeth_qdio_buffers their qdio_buffers */
-		for (j = 0; j < QDIO_MAX_BUFFERS_PER_Q; ++j) {
-			WARN_ON(queue->bufs[j]);
-			if (qeth_init_qdio_out_buf(queue, j))
-				goto out_freeoutqbufs;
-		}
 	}
 
 	/* completion */
@@ -2704,13 +2710,6 @@ static int qeth_alloc_qdio_queues(struct qeth_card *card)
 
 	return 0;
 
-out_freeoutqbufs:
-	while (j > 0) {
-		--j;
-		kmem_cache_free(qeth_qdio_outbuf_cache,
-				card->qdio.out_qs[i]->bufs[j]);
-		card->qdio.out_qs[i]->bufs[j] = NULL;
-	}
 out_freeoutq:
 	while (i > 0) {
 		qeth_free_output_queue(card->qdio.out_qs[--i]);
-- 
2.25.1

[PATCH net 2/4] s390/qeth: improve completion of pending TX buffers

[Julian Wiedmann]

The current design attaches a pending TX buffer to a custom
single-linked list, which is anchored at the buffer's slot on the
TX ring. The buffer is then checked for final completion whenever
this slot is processed during a subsequent TX NAPI poll cycle.

But if there's insufficient traffic on the ring, we might never make
enough progress to get back to this ring slot and discover the pending
buffer's final TX completion. In particular if this missing TX
completion blocks the application from sending further traffic.

So convert the custom single-linked list code to a per-queue list_head,
and scan this list on every TX NAPI cycle.

Fixes: 0da9581ddb0f ("qeth: exploit asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/qeth_core.h      |  3 +-
 drivers/s390/net/qeth_core_main.c | 69 +++++++++++++------------------
 2 files changed, 30 insertions(+), 42 deletions(-)

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index a1da83b0b0ef..91acff493612 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -436,7 +436,7 @@ struct qeth_qdio_out_buffer {
 	int is_header[QDIO_MAX_ELEMENTS_PER_BUFFER];
 
 	struct qeth_qdio_out_q *q;
-	struct qeth_qdio_out_buffer *next_pending;
+	struct list_head list_entry;
 };
 
 struct qeth_card;
@@ -500,6 +500,7 @@ struct qeth_qdio_out_q {
 	struct qdio_buffer *qdio_bufs[QDIO_MAX_BUFFERS_PER_Q];
 	struct qeth_qdio_out_buffer *bufs[QDIO_MAX_BUFFERS_PER_Q];
 	struct qdio_outbuf_state *bufstates; /* convenience pointer */
+	struct list_head pending_bufs;
 	struct qeth_out_q_stats stats;
 	spinlock_t lock;
 	unsigned int priority;
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index f7bc0ca6909b..3763cd6d14f8 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -73,8 +73,6 @@ static void qeth_free_qdio_queues(struct qeth_card *card);
 static void qeth_notify_skbs(struct qeth_qdio_out_q *queue,
 		struct qeth_qdio_out_buffer *buf,
 		enum iucv_tx_notify notification);
-static void qeth_tx_complete_buf(struct qeth_qdio_out_buffer *buf, bool error,
-				 int budget);
 
 static void qeth_close_dev_handler(struct work_struct *work)
 {
@@ -465,41 +463,6 @@ static enum iucv_tx_notify qeth_compute_cq_notification(int sbalf15,
 	return n;
 }
 
-static void qeth_cleanup_handled_pending(struct qeth_qdio_out_q *q, int bidx,
-					 int forced_cleanup)
-{
-	if (q->card->options.cq != QETH_CQ_ENABLED)
-		return;
-
-	if (q->bufs[bidx]->next_pending != NULL) {
-		struct qeth_qdio_out_buffer *head = q->bufs[bidx];
-		struct qeth_qdio_out_buffer *c = q->bufs[bidx]->next_pending;
-
-		while (c) {
-			if (forced_cleanup ||
-			    atomic_read(&c->state) == QETH_QDIO_BUF_EMPTY) {
-				struct qeth_qdio_out_buffer *f = c;
-
-				QETH_CARD_TEXT(f->q->card, 5, "fp");
-				QETH_CARD_TEXT_(f->q->card, 5, "%lx", (long) f);
-				/* release here to avoid interleaving between
-				   outbound tasklet and inbound tasklet
-				   regarding notifications and lifecycle */
-				qeth_tx_complete_buf(c, forced_cleanup, 0);
-
-				c = f->next_pending;
-				WARN_ON_ONCE(head->next_pending != f);
-				head->next_pending = c;
-				kmem_cache_free(qeth_qdio_outbuf_cache, f);
-			} else {
-				head = c;
-				c = c->next_pending;
-			}
-
-		}
-	}
-}
-
 static void qeth_qdio_handle_aob(struct qeth_card *card,
 				 unsigned long phys_aob_addr)
 {
@@ -537,7 +500,7 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
 		qeth_notify_skbs(buffer->q, buffer, notification);
 
 		/* Free dangling allocations. The attached skbs are handled by
-		 * qeth_cleanup_handled_pending().
+		 * qeth_tx_complete_pending_bufs().
 		 */
 		for (i = 0;
 		     i < aob->sb_count && i < QETH_MAX_BUFFER_ELEMENTS(card);
@@ -1488,14 +1451,35 @@ static void qeth_clear_output_buffer(struct qeth_qdio_out_q *queue,
 	atomic_set(&buf->state, QETH_QDIO_BUF_EMPTY);
 }
 
+static void qeth_tx_complete_pending_bufs(struct qeth_card *card,
+					  struct qeth_qdio_out_q *queue,
+					  bool drain)
+{
+	struct qeth_qdio_out_buffer *buf, *tmp;
+
+	list_for_each_entry_safe(buf, tmp, &queue->pending_bufs, list_entry) {
+		if (drain || atomic_read(&buf->state) == QETH_QDIO_BUF_EMPTY) {
+			QETH_CARD_TEXT(card, 5, "fp");
+			QETH_CARD_TEXT_(card, 5, "%lx", (long) buf);
+
+			qeth_tx_complete_buf(buf, drain, 0);
+
+			list_del(&buf->list_entry);
+			kmem_cache_free(qeth_qdio_outbuf_cache, buf);
+		}
+	}
+}
+
 static void qeth_drain_output_queue(struct qeth_qdio_out_q *q, bool free)
 {
 	int j;
 
+	qeth_tx_complete_pending_bufs(q->card, q, true);
+
 	for (j = 0; j < QDIO_MAX_BUFFERS_PER_Q; ++j) {
 		if (!q->bufs[j])
 			continue;
-		qeth_cleanup_handled_pending(q, j, 1);
+
 		qeth_clear_output_buffer(q, q->bufs[j], true, 0);
 		if (free) {
 			kmem_cache_free(qeth_qdio_outbuf_cache, q->bufs[j]);
@@ -2615,7 +2599,6 @@ static int qeth_init_qdio_out_buf(struct qeth_qdio_out_q *q, int bidx)
 	skb_queue_head_init(&newbuf->skb_list);
 	lockdep_set_class(&newbuf->skb_list.lock, &qdio_out_skb_queue_key);
 	newbuf->q = q;
-	newbuf->next_pending = q->bufs[bidx];
 	atomic_set(&newbuf->state, QETH_QDIO_BUF_EMPTY);
 	q->bufs[bidx] = newbuf;
 	return 0;
@@ -2697,6 +2680,7 @@ static int qeth_alloc_qdio_queues(struct qeth_card *card)
 		card->qdio.out_qs[i] = queue;
 		queue->card = card;
 		queue->queue_no = i;
+		INIT_LIST_HEAD(&queue->pending_bufs);
 		spin_lock_init(&queue->lock);
 		timer_setup(&queue->timer, qeth_tx_completion_timer, 0);
 		queue->coalesce_usecs = QETH_TX_COALESCE_USECS;
@@ -6106,6 +6090,8 @@ static void qeth_iqd_tx_complete(struct qeth_qdio_out_q *queue,
 					qeth_schedule_recovery(card);
 				}
 
+				list_add(&buffer->list_entry,
+					 &queue->pending_bufs);
 				/* Skip clearing the buffer: */
 				return;
 			case QETH_QDIO_BUF_QAOB_OK:
@@ -6161,6 +6147,8 @@ static int qeth_tx_poll(struct napi_struct *napi, int budget)
 		unsigned int bytes = 0;
 		int completed;
 
+		qeth_tx_complete_pending_bufs(card, queue, false);
+
 		if (qeth_out_queue_is_empty(queue)) {
 			napi_complete(napi);
 			return 0;
@@ -6193,7 +6181,6 @@ static int qeth_tx_poll(struct napi_struct *napi, int budget)
 
 			qeth_handle_send_error(card, buffer, error);
 			qeth_iqd_tx_complete(queue, bidx, error, budget);
-			qeth_cleanup_handled_pending(queue, bidx, false);
 		}
 
 		netdev_tx_completed_queue(txq, packets, bytes);
-- 
2.25.1

[PATCH net 3/4] s390/qeth: schedule TX NAPI on QAOB completion

[Julian Wiedmann]

When a QAOB notifies us that a pending TX buffer has been delivered, the
actual TX completion processing by qeth_tx_complete_pending_bufs()
is done within the context of a TX NAPI instance. We shouldn't rely on
this instance being scheduled by some other TX event, but just do it
ourselves.

qeth_qdio_handle_aob() is called from qeth_poll(), ie. our main NAPI
instance. To avoid touching the TX queue's NAPI instance
before/after it is (un-)registered, reorder the code in qeth_open()
and qeth_stop() accordingly.

Fixes: 0da9581ddb0f ("qeth: exploit asynchronous delivery of storage blocks")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/qeth_core_main.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 3763cd6d14f8..d0a56afec028 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -470,6 +470,7 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
 	struct qaob *aob;
 	struct qeth_qdio_out_buffer *buffer;
 	enum iucv_tx_notify notification;
+	struct qeth_qdio_out_q *queue;
 	unsigned int i;
 
 	aob = (struct qaob *) phys_to_virt(phys_aob_addr);
@@ -512,7 +513,9 @@ static void qeth_qdio_handle_aob(struct qeth_card *card,
 			buffer->is_header[i] = 0;
 		}
 
+		queue = buffer->q;
 		atomic_set(&buffer->state, QETH_QDIO_BUF_EMPTY);
+		napi_schedule(&queue->napi);
 		break;
 	default:
 		WARN_ON_ONCE(1);
@@ -7235,9 +7238,7 @@ int qeth_open(struct net_device *dev)
 	card->data.state = CH_STATE_UP;
 	netif_tx_start_all_queues(dev);
 
-	napi_enable(&card->napi);
 	local_bh_disable();
-	napi_schedule(&card->napi);
 	if (IS_IQD(card)) {
 		struct qeth_qdio_out_q *queue;
 		unsigned int i;
@@ -7249,8 +7250,12 @@ int qeth_open(struct net_device *dev)
 			napi_schedule(&queue->napi);
 		}
 	}
+
+	napi_enable(&card->napi);
+	napi_schedule(&card->napi);
 	/* kick-start the NAPI softirq: */
 	local_bh_enable();
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(qeth_open);
@@ -7260,6 +7265,11 @@ int qeth_stop(struct net_device *dev)
 	struct qeth_card *card = dev->ml_priv;
 
 	QETH_CARD_TEXT(card, 4, "qethstop");
+
+	napi_disable(&card->napi);
+	cancel_delayed_work_sync(&card->buffer_reclaim_work);
+	qdio_stop_irq(CARD_DDEV(card));
+
 	if (IS_IQD(card)) {
 		struct qeth_qdio_out_q *queue;
 		unsigned int i;
@@ -7280,10 +7290,6 @@ int qeth_stop(struct net_device *dev)
 		netif_tx_disable(dev);
 	}
 
-	napi_disable(&card->napi);
-	cancel_delayed_work_sync(&card->buffer_reclaim_work);
-	qdio_stop_irq(CARD_DDEV(card));
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(qeth_stop);
-- 
2.25.1

[PATCH net 4/4] s390/qeth: fix notification for pending buffers during teardown

[Julian Wiedmann]

The cited commit reworked the state machine for pending TX buffers.
In qeth_iqd_tx_complete() it turned PENDING into a transient state, and
uses NEED_QAOB for buffers that get parked while waiting for their QAOB
completion.

But it missed to adjust the check in qeth_tx_complete_buf(). So if
qeth_tx_complete_pending_bufs() is called during teardown to drain
the parked TX buffers, we no longer raise a notification for af_iucv.

Instead of updating the checked state, just move this code into
qeth_tx_complete_pending_bufs() itself. This also gets rid of the
special-case in the common TX completion path.

Fixes: 8908f36d20d8 ("s390/qeth: fix af_iucv notification race")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/qeth_core_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index d0a56afec028..a814698387bc 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -1390,9 +1390,6 @@ static void qeth_tx_complete_buf(struct qeth_qdio_out_buffer *buf, bool error,
 	struct qeth_qdio_out_q *queue = buf->q;
 	struct sk_buff *skb;
 
-	if (atomic_read(&buf->state) == QETH_QDIO_BUF_PENDING)
-		qeth_notify_skbs(queue, buf, TX_NOTIFY_GENERALERROR);
-
 	/* Empty buffer? */
 	if (buf->next_element_to_fill == 0)
 		return;
@@ -1465,6 +1462,9 @@ static void qeth_tx_complete_pending_bufs(struct qeth_card *card,
 			QETH_CARD_TEXT(card, 5, "fp");
 			QETH_CARD_TEXT_(card, 5, "%lx", (long) buf);
 
+			if (drain)
+				qeth_notify_skbs(queue, buf,
+						 TX_NOTIFY_GENERALERROR);
 			qeth_tx_complete_buf(buf, drain, 0);
 
 			list_del(&buf->list_entry);
-- 
2.25.1

Re: [PATCH net 0/4] s390/qeth: fixes 2021-03-09

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (refs/heads/master):

On Tue,  9 Mar 2021 17:52:17 +0100 you wrote:
> Hi Dave & Jakub,
> 
> please apply the following patch series to netdev's net tree.
> 
> This brings one fix for a memleak in an error path of the setup code.
> Also several fixes for dealing with pending TX buffers - two for old
> bugs in their completion handling, and one recent regression in a
> teardown path.
> 
> [...]

Here is the summary with links:
  - [net,1/4] s390/qeth: fix memory leak after failed TX Buffer allocation
    https://git.kernel.org/netdev/net/c/e7a36d27f6b9
  - [net,2/4] s390/qeth: improve completion of pending TX buffers
    https://git.kernel.org/netdev/net/c/c20383ad1656
  - [net,3/4] s390/qeth: schedule TX NAPI on QAOB completion
    https://git.kernel.org/netdev/net/c/3e83d467a08e
  - [net,4/4] s390/qeth: fix notification for pending buffers during teardown
    https://git.kernel.org/netdev/net/c/7eefda7f353e

You are awesome, thank you!
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