Skip to content

Commit

Permalink
atl1c: Work around the DMA RX overflow issue
Browse files Browse the repository at this point in the history 
[ Upstream commit 8656568 ]

This is based on alx driver commit 881d032 ("net: alx: Work around
the DMA RX overflow issue").

The alx and atl1c drivers had RX overflow error which was why a custom
allocator was created to avoid certain addresses. The simpler workaround
then created for alx driver, but not for atl1c due to lack of tester.

Instead of using a custom allocator, check the allocated skb address and
use skb_reserve() to move away from problematic 0x...fc0 address.

Tested on AR8131 on Acer 4540.

Signed-off-by: Sieng-Piaw Liew <liew.s.piaw@gmail.com>
Link: https://lore.kernel.org/r/20230912010711.12036-1-liew.s.piaw@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
  • Loading branch information
@spliew89 @gregkh
spliew89 authored and gregkh committed Nov 28, 2023
1 parent 2be24c4 commit 57e44ff
Show file tree
Hide file tree
Showing 2 changed files with 16 additions and 54 deletions.
3 changes: 0 additions & 3 deletions drivers/net/ethernet/atheros/atl1c/atl1c.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -504,15 +504,12 @@ struct atl1c_rrd_ring {
u16 next_to_use;
u16 next_to_clean;
struct napi_struct napi;
struct page *rx_page;
unsigned int rx_page_offset;
};

/* board specific private data structure */
struct atl1c_adapter {
struct net_device *netdev;
struct pci_dev *pdev;
unsigned int rx_frag_size;
struct atl1c_hw hw;
struct atl1c_hw_stats hw_stats;
struct mii_if_info mii; /* MII interface info */
Expand Down
67 changes: 16 additions & 51 deletions drivers/net/ethernet/atheros/atl1c/atl1c_main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -493,15 +493,10 @@ static int atl1c_set_mac_addr(struct net_device *netdev, void *p)
static void atl1c_set_rxbufsize(struct atl1c_adapter *adapter,
struct net_device *dev)
{
unsigned int head_size;
int mtu = dev->mtu;

adapter->rx_buffer_len = mtu > AT_RX_BUF_SIZE ?
roundup(mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN, 8) : AT_RX_BUF_SIZE;

head_size = SKB_DATA_ALIGN(adapter->rx_buffer_len + NET_SKB_PAD + NET_IP_ALIGN) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
adapter->rx_frag_size = roundup_pow_of_two(head_size);
}

static netdev_features_t atl1c_fix_features(struct net_device *netdev,
Expand Down Expand Up @@ -974,7 +969,6 @@ static void atl1c_init_ring_ptrs(struct atl1c_adapter *adapter)
static void atl1c_free_ring_resources(struct atl1c_adapter *adapter)
{
struct pci_dev *pdev = adapter->pdev;
int i;

dma_free_coherent(&pdev->dev, adapter->ring_header.size,
adapter->ring_header.desc, adapter->ring_header.dma);
Expand All @@ -987,12 +981,6 @@ static void atl1c_free_ring_resources(struct atl1c_adapter *adapter)
kfree(adapter->tpd_ring[0].buffer_info);
adapter->tpd_ring[0].buffer_info = NULL;
}
for (i = 0; i < adapter->rx_queue_count; ++i) {
if (adapter->rrd_ring[i].rx_page) {
put_page(adapter->rrd_ring[i].rx_page);
adapter->rrd_ring[i].rx_page = NULL;
}
}
}

/**
Expand Down Expand Up @@ -1764,48 +1752,11 @@ static inline void atl1c_rx_checksum(struct atl1c_adapter *adapter,
skb_checksum_none_assert(skb);
}

static struct sk_buff *atl1c_alloc_skb(struct atl1c_adapter *adapter,
u32 queue, bool napi_mode)
{
struct atl1c_rrd_ring *rrd_ring = &adapter->rrd_ring[queue];
struct sk_buff *skb;
struct page *page;

if (adapter->rx_frag_size > PAGE_SIZE) {
if (likely(napi_mode))
return napi_alloc_skb(&rrd_ring->napi,
adapter->rx_buffer_len);
else
return netdev_alloc_skb_ip_align(adapter->netdev,
adapter->rx_buffer_len);
}

page = rrd_ring->rx_page;
if (!page) {
page = alloc_page(GFP_ATOMIC);
if (unlikely(!page))
return NULL;
rrd_ring->rx_page = page;
rrd_ring->rx_page_offset = 0;
}

skb = build_skb(page_address(page) + rrd_ring->rx_page_offset,
adapter->rx_frag_size);
if (likely(skb)) {
skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
rrd_ring->rx_page_offset += adapter->rx_frag_size;
if (rrd_ring->rx_page_offset >= PAGE_SIZE)
rrd_ring->rx_page = NULL;
else
get_page(page);
}
return skb;
}

static int atl1c_alloc_rx_buffer(struct atl1c_adapter *adapter, u32 queue,
bool napi_mode)
{
struct atl1c_rfd_ring *rfd_ring = &adapter->rfd_ring[queue];
struct atl1c_rrd_ring *rrd_ring = &adapter->rrd_ring[queue];
struct pci_dev *pdev = adapter->pdev;
struct atl1c_buffer *buffer_info, *next_info;
struct sk_buff *skb;
Expand All @@ -1824,13 +1775,27 @@ static int atl1c_alloc_rx_buffer(struct atl1c_adapter *adapter, u32 queue,
while (next_info->flags & ATL1C_BUFFER_FREE) {
rfd_desc = ATL1C_RFD_DESC(rfd_ring, rfd_next_to_use);

skb = atl1c_alloc_skb(adapter, queue, napi_mode);
/* When DMA RX address is set to something like
* 0x....fc0, it will be very likely to cause DMA
* RFD overflow issue.
*
* To work around it, we apply rx skb with 64 bytes
* longer space, and offset the address whenever
* 0x....fc0 is detected.
*/
if (likely(napi_mode))
skb = napi_alloc_skb(&rrd_ring->napi, adapter->rx_buffer_len + 64);
else
skb = netdev_alloc_skb(adapter->netdev, adapter->rx_buffer_len + 64);
if (unlikely(!skb)) {
if (netif_msg_rx_err(adapter))
dev_warn(&pdev->dev, "alloc rx buffer failed\n");
break;
}

if (((unsigned long)skb->data & 0xfff) == 0xfc0)
skb_reserve(skb, 64);

/*
* Make buffer alignment 2 beyond a 16 byte boundary
* this will result in a 16 byte aligned IP header after
Expand Down

0 comments on commit 57e44ff

Please sign in to comment.