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Subject[PATCH AUTOSEL for 4.9 17/52] net: arc_emac: fix arc_emac_rx() error paths
Date
From: Alexander Kochetkov <al.kochet@gmail.com>

[ Upstream commit e688822d035b494071ecbadcccbd6f3325fb0f59 ]

arc_emac_rx() has some issues found by code review.

In case netdev_alloc_skb_ip_align() or dma_map_single() failure
rx fifo entry will not be returned to EMAC.

In case dma_map_single() failure previously allocated skb became
lost to driver. At the same time address of newly allocated skb
will not be provided to EMAC.

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/net/ethernet/arc/emac_main.c | 53 +++++++++++++++++++++---------------
1 file changed, 31 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
index be865b4dada2..aba4853e6b70 100644
--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -210,39 +210,48 @@ static int arc_emac_rx(struct net_device *ndev, int budget)
continue;
}

- pktlen = info & LEN_MASK;
- stats->rx_packets++;
- stats->rx_bytes += pktlen;
- skb = rx_buff->skb;
- skb_put(skb, pktlen);
- skb->dev = ndev;
- skb->protocol = eth_type_trans(skb, ndev);
-
- dma_unmap_single(&ndev->dev, dma_unmap_addr(rx_buff, addr),
- dma_unmap_len(rx_buff, len), DMA_FROM_DEVICE);
-
- /* Prepare the BD for next cycle */
- rx_buff->skb = netdev_alloc_skb_ip_align(ndev,
- EMAC_BUFFER_SIZE);
- if (unlikely(!rx_buff->skb)) {
+ /* Prepare the BD for next cycle. netif_receive_skb()
+ * only if new skb was allocated and mapped to avoid holes
+ * in the RX fifo.
+ */
+ skb = netdev_alloc_skb_ip_align(ndev, EMAC_BUFFER_SIZE);
+ if (unlikely(!skb)) {
+ if (net_ratelimit())
+ netdev_err(ndev, "cannot allocate skb\n");
+ /* Return ownership to EMAC */
+ rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
stats->rx_errors++;
- /* Because receive_skb is below, increment rx_dropped */
stats->rx_dropped++;
continue;
}

- /* receive_skb only if new skb was allocated to avoid holes */
- netif_receive_skb(skb);
-
- addr = dma_map_single(&ndev->dev, (void *)rx_buff->skb->data,
+ addr = dma_map_single(&ndev->dev, (void *)skb->data,
EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
if (dma_mapping_error(&ndev->dev, addr)) {
if (net_ratelimit())
- netdev_err(ndev, "cannot dma map\n");
- dev_kfree_skb(rx_buff->skb);
+ netdev_err(ndev, "cannot map dma buffer\n");
+ dev_kfree_skb(skb);
+ /* Return ownership to EMAC */
+ rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
stats->rx_errors++;
+ stats->rx_dropped++;
continue;
}
+
+ /* unmap previosly mapped skb */
+ dma_unmap_single(&ndev->dev, dma_unmap_addr(rx_buff, addr),
+ dma_unmap_len(rx_buff, len), DMA_FROM_DEVICE);
+
+ pktlen = info & LEN_MASK;
+ stats->rx_packets++;
+ stats->rx_bytes += pktlen;
+ skb_put(rx_buff->skb, pktlen);
+ rx_buff->skb->dev = ndev;
+ rx_buff->skb->protocol = eth_type_trans(rx_buff->skb, ndev);
+
+ netif_receive_skb(rx_buff->skb);
+
+ rx_buff->skb = skb;
dma_unmap_addr_set(rx_buff, addr, addr);
dma_unmap_len_set(rx_buff, len, EMAC_BUFFER_SIZE);

--
2.11.0
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