This is a note to let you know that I've just added the patch titled

net: arc_emac: fix arc_emac_rx() error paths

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: net-arc_emac-fix-arc_emac_rx-error-paths.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Feb 28 16:19:30 CET 2018

From: Alexander Kochetkov al.kochet@gmail.com Date: Fri, 15 Dec 2017 20:20:06 +0300 Subject: net: arc_emac: fix arc_emac_rx() error paths

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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/arc/emac_main.c | 53 ++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 22 deletions(-)

--- a/drivers/net/ethernet/arc/emac_main.c +++ b/drivers/net/ethernet/arc/emac_main.c @@ -250,39 +250,48 @@ static int arc_emac_rx(struct net_device 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);

Patches currently in stable-queue which might be from al.kochet@gmail.com are

queue-4.4/net-arc_emac-fix-arc_emac_rx-error-paths.patch