[PATCH net-next v3 5/5] TEST ONLY: lan743x: skb_trim failure test

Sven Van Asbroeck
2021-02-16T01:10:31Z

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

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

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: Hillf Danton <hdanton@sina.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

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 6e1b3c996bd7..4751626f4c0f 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, buffer_length, can_fail);
+ skb = __netdev_alloc_skb(netdev, buffer_length, GFP_ATOMIC | GFP_DMA);
if (!skb)
return -ENOMEM;
dma_ptr = dma_map_single(dev, skb->data, buffer_length, DMA_FROM_DEVICE);
@@ -2078,6 +2065,13 @@ 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;
@@ -2152,7 +2146,7 @@ static int lan743x_rx_process_buffer(struct lan743x_rx *rx)

/* save existing skb, allocate new skb and map to dma */
skb = buffer_info->skb;
- 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.
@@ -2357,7 +2351,7 @@ 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