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net: ethernet: cortina: Carry over frag counter

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The gmac_rx() NAPI poll function assembles packets in an
SKB from a ring buffer.

If the ring buffer gets completely emptied during a poll cycle,
we exit gmac_rx(), but the packet is not yet completely
assembled in the SKB, yet the fragment counter frag_nr is
reset to zero on the next invocation.

Solve this by making the RX fragment counter a part of the
port struct, and carry it over between invocations.

Reset the fragment counter only right after calling
napi_gro_frags(), on error (after calling napi_free_frags())
or if stopping the port.

Reset it in some place where not strictly necessary just to
emphasize what is going on.

This was found by Sashiko during normal patch review.

Fixes: 4d5ae32f5e ("net: ethernet: Add a driver for Gemini gigabit ethernet")
Link: https://sashiko.dev/#/patchset/20260505-gemini-ethernet-fix-v2-1-997c31d06079%40kernel.org
Signed-off-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260509-gemini-ethernet-fixes-v1-3-6c5d20ddc35b@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Linus Walleij
2026-05-09 00:13:38 +02:00
committed by Paolo Abeni
parent 06937db21e
commit ebd8ec2b30
1 changed files with 8 additions and 1 deletions
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9
drivers/net/ethernet/cortina/gemini.c
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@@ -123,6 +123,7 @@ struct gemini_ethernet_port {
struct hrtimer rx_coalesce_timer;
unsigned int rx_coalesce_nsecs;
struct sk_buff *rx_skb;
unsigned int rx_frag_nr;
unsigned int freeq_refill;
struct gmac_txq txq[TX_QUEUE_NUM];
@@ -1444,6 +1445,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
unsigned short m = (1 << port->rxq_order) - 1;
struct gemini_ethernet *geth = port->geth;
void __iomem *ptr_reg = port->rxq_rwptr;
unsigned int frag_nr = port->rx_frag_nr;
struct sk_buff *skb = port->rx_skb;
unsigned int frame_len, frag_len;
struct gmac_rxdesc *rx = NULL;
@@ -1457,7 +1459,6 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
unsigned short r, w;
union dma_rwptr rw;
dma_addr_t mapping;
int frag_nr = 0;
spin_lock_irqsave(&geth->irq_lock, flags);
rw.bits32 = readl(ptr_reg);
@@ -1497,6 +1498,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
if (skb) {
napi_free_frags(&port->napi);
skb = NULL;
frag_nr = 0;
}
continue;
}
@@ -1507,6 +1509,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
napi_free_frags(&port->napi);
port->stats.rx_dropped++;
skb = NULL;
frag_nr = 0;
}
skb = gmac_skb_if_good_frame(port, word0, frame_len);
@@ -1541,6 +1544,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
if (word3.bits32 & EOF_BIT) {
napi_gro_frags(&port->napi);
skb = NULL;
frag_nr = 0;
--budget;
}
continue;
@@ -1549,6 +1553,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
if (skb) {
napi_free_frags(&port->napi);
skb = NULL;
frag_nr = 0;
}
if (mapping)
@@ -1558,6 +1563,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
}
port->rx_skb = skb;
port->rx_frag_nr = frag_nr;
writew(r, ptr_reg);
return budget;
}
@@ -1886,6 +1892,7 @@ static int gmac_stop(struct net_device *netdev)
gmac_stop_dma(port);
napi_disable(&port->napi);
port->rx_skb = NULL;
port->rx_frag_nr = 0;
gmac_enable_irq(netdev, 0);
gmac_cleanup_rxq(netdev);