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macb1 checksum fixes #7552

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macb1 checksum fixes #7552

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bcda4cb
net: macb: exclude software FCS from TX byte statistics
nbuchwitz Aug 13, 2026
ecebe6c
net: macb: fix zero UDP checksum on transmit
nbuchwitz Aug 13, 2026
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3 changes: 3 additions & 0 deletions drivers/net/ethernet/cadence/macb.h
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Original file line number Diff line number Diff line change
Expand Up @@ -996,13 +996,16 @@ struct macb_dma_desc_ptp {
* of the frame
* @mapping: DMA address of the skb's fragment buffer
* @size: size of the DMA mapped buffer
* @skb_len: skb->len as handed over by the stack, before padding and
* software FCS, only set for the last buffer of the frame
* @mapped_as_page: true when buffer was mapped with skb_frag_dma_map(),
* false when buffer was mapped with dma_map_single()
*/
struct macb_tx_skb {
struct sk_buff *skb;
dma_addr_t mapping;
size_t size;
unsigned int skb_len;
bool mapped_as_page;
};

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24 changes: 17 additions & 7 deletions drivers/net/ethernet/cadence/macb_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1355,8 +1355,8 @@ static void macb_tx_error_task(struct work_struct *work)
bp->dev->stats.tx_packets++;
queue->stats.tx_packets++;
packets++;
bp->dev->stats.tx_bytes += skb->len;
queue->stats.tx_bytes += skb->len;
bp->dev->stats.tx_bytes += tx_skb->skb_len;
queue->stats.tx_bytes += tx_skb->skb_len;
bytes += skb->len;
}
} else {
Expand Down Expand Up @@ -1483,8 +1483,8 @@ static int macb_tx_complete(struct macb_queue *queue, int budget)
skb->data);
bp->dev->stats.tx_packets++;
queue->stats.tx_packets++;
bp->dev->stats.tx_bytes += skb->len;
queue->stats.tx_bytes += skb->len;
bp->dev->stats.tx_bytes += tx_skb->skb_len;
queue->stats.tx_bytes += tx_skb->skb_len;
packets++;
bytes += skb->len;
}
Expand Down Expand Up @@ -2262,7 +2262,8 @@ static void macb_poll_controller(struct net_device *dev)
static unsigned int macb_tx_map(struct macb *bp,
struct macb_queue *queue,
struct sk_buff *skb,
unsigned int hdrlen)
unsigned int hdrlen,
unsigned int skb_len)
{
dma_addr_t mapping;
unsigned int len, entry, i, tx_head = queue->tx_head;
Expand Down Expand Up @@ -2351,6 +2352,7 @@ static unsigned int macb_tx_map(struct macb *bp,

/* This is the last buffer of the frame: save socket buffer */
tx_skb->skb = skb;
tx_skb->skb_len = skb_len;

/* Update TX ring: update buffer descriptors in reverse order
* to avoid race condition
Expand Down Expand Up @@ -2474,6 +2476,13 @@ static inline int macb_clear_csum(struct sk_buff *skb)
if (skb->ip_summed != CHECKSUM_PARTIAL)
return 0;

/* The hardware lacks the RFC 768 substitution of 0xffff for a
* UDP checksum that computes to zero, complete UDP in software.
*/
if (skb->csum_offset == offsetof(struct udphdr, check) &&
!ptp_one_step_sync(skb))
return skb_checksum_help(skb);

/* make sure we can modify the header */
if (unlikely(skb_cow_head(skb, 0)))
return -1;
Expand Down Expand Up @@ -2543,7 +2552,7 @@ static netdev_tx_t macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
struct macb *bp = netdev_priv(dev);
struct macb_queue *queue = &bp->queues[queue_index];
unsigned int desc_cnt, nr_frags, frag_size, f;
unsigned int hdrlen;
unsigned int hdrlen, skb_len;
unsigned long flags;
bool is_lso;
netdev_tx_t ret = NETDEV_TX_OK;
Expand All @@ -2553,6 +2562,7 @@ static netdev_tx_t macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
return ret;
}

skb_len = skb->len;
if (macb_pad_and_fcs(&skb, dev)) {
dev_kfree_skb_any(skb);
return ret;
Expand Down Expand Up @@ -2618,7 +2628,7 @@ static netdev_tx_t macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
}

/* Map socket buffer for DMA transfer */
if (!macb_tx_map(bp, queue, skb, hdrlen)) {
if (!macb_tx_map(bp, queue, skb, hdrlen, skb_len)) {
dev_kfree_skb_any(skb);
goto unlock;
}
Expand Down
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