[PATCH net-next v1 5/6] TEST ONLY: lan743x: skb_alloc failure test

From: Sven Van Asbroeck
Date: Fri Jan 29 2021 - 15:01:09 EST


From: Sven Van Asbroeck <thesven73@xxxxxxxxx>

Simulate low-memory in lan743x_rx_allocate_skb(): fail 10
allocations in a row in every 100.

Signed-off-by: Sven Van Asbroeck <thesven73@xxxxxxxxx>
---

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

To: Bryan Whitehead <bryan.whitehead@xxxxxxxxxxxxx>
To: UNGLinuxDriver@xxxxxxxxxxxxx
To: "David S. Miller" <davem@xxxxxxxxxxxxx>
To: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Andrew Lunn <andrew@xxxxxxx>
Cc: Alexey Denisov <rtgbnm@xxxxxxxxx>
Cc: Sergej Bauer <sbauer@xxxxxxxxxxx>
Cc: Tim Harvey <tharvey@xxxxxxxxxxxxx>
Cc: Anders Rønningen <anders@xxxxxxxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx (open list)

drivers/net/ethernet/microchip/lan743x_main.c | 21 +++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index ed4959ad9237..149b482fd984 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1963,7 +1963,20 @@ static void lan743x_rx_update_tail(struct lan743x_rx *rx, int index)
index);
}

-static int lan743x_rx_init_ring_element(struct lan743x_rx *rx, int 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)
{
struct net_device *netdev = rx->adapter->netdev;
struct device *dev = &rx->adapter->pdev->dev;
@@ -1977,7 +1990,7 @@ static int lan743x_rx_init_ring_element(struct lan743x_rx *rx, int index)

descriptor = &rx->ring_cpu_ptr[index];
buffer_info = &rx->buffer_info[index];
- skb = __netdev_alloc_skb(netdev, length, GFP_ATOMIC | GFP_DMA);
+ skb = lan743x_alloc_skb(netdev, length, can_fail);
if (!skb)
return -ENOMEM;
dma_ptr = dma_map_single(dev, skb->data, length, DMA_FROM_DEVICE);
@@ -2130,7 +2143,7 @@ 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)) {
+ if (lan743x_rx_init_ring_element(rx, rx->last_head, true)) {
/* failed to allocate next skb.
* Memory is very low.
* Drop this packet and reuse buffer.
@@ -2330,7 +2343,7 @@ 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);
+ ret = lan743x_rx_init_ring_element(rx, index, false);
if (ret)
goto cleanup;
}
--
2.17.1