linux-kernel - [PATCH 5.7 281/393] s390/qeth: tolerate pre-filled RX buffer

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Message-Id: <20200817143833.250363826@linuxfoundation.org>
Date:   Mon, 17 Aug 2020 17:15:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Julian Wiedmann <jwi@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 281/393] s390/qeth: tolerate pre-filled RX buffer

From: Julian Wiedmann <jwi@...ux.ibm.com>

[ Upstream commit eff73e16ee116f6eafa2be48fab42659a27cb453 ]

When preparing a buffer for RX refill, tolerate that it already has a
pool_entry attached. Otherwise we could easily leak such a pool_entry
when re-driving the RX refill after an error (from eg. do_qdio()).

This needs some minor adjustment in the code that drains RX buffer(s)
prior to RX refill and during teardown, so that ->pool_entry is NULLed
accordingly.

Fixes: 4a71df50047f ("qeth: new qeth device driver")
Signed-off-by: Julian Wiedmann <jwi@...ux.ibm.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/s390/net/qeth_core_main.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 60d675fefac7d..40ddd17864304 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -202,12 +202,17 @@ 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);
 
@@ -2671,7 +2676,7 @@ 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)) {
@@ -2682,9 +2687,13 @@ 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
@@ -2692,8 +2701,6 @@ 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 =
@@ -5521,6 +5528,7 @@ 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);
+			buffer->pool_entry = NULL;
 			qeth_queue_input_buffer(card, card->rx.b_index);
 			card->rx.b_count--;
 
-- 
2.25.1