netdev - [PATCH net-next] sfc: The RX page

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Date:   Sat, 01 Jan 2022 11:33:00 +0000
From:   Martin Habets <habetsm.xilinx@...il.com>
To:     kuba@...nel.org, jiasheng@...as.ac.cn, davem@...emloft.net
Cc:     ecree.xilinx@...il.com, netdev@...r.kernel.org
Subject: [PATCH net-next] sfc: The RX page_ring is optional

The RX page_ring is an optional feature that improves
performance. When allocation fails the driver can still
function, but possibly with a lower bandwidth.
Guard against dereferencing a NULL page_ring.

Fixes: 2768935a4660 ("sfc: reuse pages to avoid DMA mapping/unmapping costs")
Signed-off-by: Martin Habets <habetsm.xilinx@...il.com>
Reported-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
 drivers/net/ethernet/sfc/falcon/rx.c |    5 +++++
 drivers/net/ethernet/sfc/rx_common.c |    5 +++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/net/ethernet/sfc/falcon/rx.c b/drivers/net/ethernet/sfc/falcon/rx.c
index 11a6aee852e9..57874adfb1b2 100644
--- a/drivers/net/ethernet/sfc/falcon/rx.c
+++ b/drivers/net/ethernet/sfc/falcon/rx.c
@@ -110,6 +110,8 @@ static struct page *ef4_reuse_page(struct ef4_rx_queue *rx_queue)
 	struct ef4_rx_page_state *state;
 	unsigned index;
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
 	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
 	page = rx_queue->page_ring[index];
 	if (page == NULL)
@@ -293,6 +295,9 @@ static void ef4_recycle_rx_pages(struct ef4_channel *channel,
 {
 	struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
+
 	do {
 		ef4_recycle_rx_page(channel, rx_buf);
 		rx_buf = ef4_rx_buf_next(rx_queue, rx_buf);
diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
index 0983abc0cc5f..9ea50617dd04 100644
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -45,6 +45,8 @@ static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue)
 	unsigned int index;
 	struct page *page;
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
 	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
 	page = rx_queue->page_ring[index];
 	if (page == NULL)
@@ -114,6 +116,9 @@ void efx_recycle_rx_pages(struct efx_channel *channel,
 {
 	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
 
+	if (unlikely(!rx_queue->page_ring))
+		return NULL;
+
 	do {
 		efx_recycle_rx_page(channel, rx_buf);
 		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);