[PATCH net-next v1 6/6] TEST ONLY: lan743x: skb_trim failure test

[Sven Van Asbroeck <thesven73@gmail.com>]

From: Sven Van Asbroeck <thesven73@gmail.com>

Simulate low-memory in lan743x_rx_trim_skb(): fail one allocation
in every 100.

Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
---

Tree: git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git # 46eb3c108fe1

To: Bryan Whitehead <bryan.whitehead@microchip.com>
To: UNGLinuxDriver@microchip.com
To: "David S. Miller" <davem@davemloft.net>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Alexey Denisov <rtgbnm@gmail.com>
Cc: Sergej Bauer <sbauer@blackbox.su>
Cc: Tim Harvey <tharvey@gateworks.com>
Cc: Anders Rønningen <anders@ronningen.priv.no>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org (open list)

 drivers/net/ethernet/microchip/lan743x_main.c | 28 ++++++++-----------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 149b482fd984..dfae7745094b 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1963,20 +1963,7 @@ static void lan743x_rx_update_tail(struct lan743x_rx *rx, int index)
 				  index);
 }
 
-static struct sk_buff *
-lan743x_alloc_skb(struct net_device *netdev, int length, bool can_fail)
-{
-	static int rx_alloc;
-	int counter = rx_alloc++ % 100;
-
-	if (can_fail && counter >= 20 && counter < 30)
-		return NULL;
-
-	return __netdev_alloc_skb(netdev, length, GFP_ATOMIC | GFP_DMA);
-}
-
-static int
-lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index, bool can_fail)
+static int lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index)
 {
 	struct net_device *netdev = rx->adapter->netdev;
 	struct device *dev = &rx->adapter->pdev->dev;
@@ -1990,7 +1977,7 @@ lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index, bool can_fail)
 
 	descriptor = &rx->ring_cpu_ptr[index];
 	buffer_info = &rx->buffer_info[index];
-	skb = lan743x_alloc_skb(netdev, length, can_fail);
+	skb = __netdev_alloc_skb(netdev, length, GFP_ATOMIC | GFP_DMA);
 	if (!skb)
 		return -ENOMEM;
 	dma_ptr = dma_map_single(dev, skb->data, length, DMA_FROM_DEVICE);
@@ -2058,6 +2045,13 @@ static void lan743x_rx_release_ring_element(struct lan743x_rx *rx, int index)
 static struct sk_buff *
 lan743x_rx_trim_skb(struct sk_buff *skb, int frame_length)
 {
+	static int trim_cnt;
+
+	if ((trim_cnt++ % 100) == 77) {
+		dev_kfree_skb_irq(skb);
+		return NULL;
+	}
+
 	if (skb_linearize(skb)) {
 		dev_kfree_skb_irq(skb);
 		return NULL;
@@ -2143,7 +2137,7 @@ static int lan743x_rx_process_packet(struct lan743x_rx *rx)
 	skb = buffer_info->skb;
 
 	/* allocate new skb and map to dma */
-	if (lan743x_rx_init_ring_element(rx, rx->last_head, true)) {
+	if (lan743x_rx_init_ring_element(rx, rx->last_head)) {
 		/* failed to allocate next skb.
 		 * Memory is very low.
 		 * Drop this packet and reuse buffer.
@@ -2343,7 +2337,7 @@ static int lan743x_rx_ring_init(struct lan743x_rx *rx)
 
 	rx->last_head = 0;
 	for (index = 0; index < rx->ring_size; index++) {
-		ret = lan743x_rx_init_ring_element(rx, index, false);
+		ret = lan743x_rx_init_ring_element(rx, index);
 		if (ret)
 			goto cleanup;
 	}
-- 
2.17.1