Commit ebd8ec2b authored by Linus Walleij's avatar Linus Walleij Committed by Paolo Abeni
Browse files

net: ethernet: cortina: Carry over frag counter 

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: 4d5ae32f ("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: default avatarLinus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260509-gemini-ethernet-fixes-v1-3-6c5d20ddc35b@kernel.org


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 06937db2

drivers/net/ethernet/cortina/gemini.c

+8 −1
Original line number Diff line number Diff line
@@ -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);