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net: bgmac: rate limit RX error messages

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When the RX ring is full the RX FIFO overflows. With RX overflow
continue enabled, the DMA engine then writes one frame with a bogus
length (always 0x45c2 on a BCM4716), which the driver drops with
"Found oversized packet at slot %d, DMA issue!".

Under sustained overload this happens on every NAPI poll. On an Asus
RT-N16 a 950 Mbit/s UDP stream to the router printed about 1450 such
lines in 20 seconds. The messages are printed from NAPI context, so
with a serial console the router spends most of its time printing.

The frames are already accounted in rx_length_errors and rx_errors.
Rate limit both RX error messages. With this change the same flood
printed 60 lines while rx_length_errors counted 14297 dropped frames.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://patch.msgid.link/20261018231629.39734-1-rosenp@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Rosen Penev 2026-10-18 16:16:29 -07:00 committed by Jakub Kicinski
parent 5a3dcad8e1
commit 77dac783f1
1 changed files with 6 additions and 4 deletions
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10
drivers/net/ethernet/broadcom/bgmac.c
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@ -447,16 +447,18 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
/* Check for poison and drop or pass the packet */
if (len == 0xdead && flags == 0xbeef) {
netdev_err(bgmac->net_dev, "Found poisoned packet at slot %d, DMA issue!\n",
ring->start);
if (net_ratelimit())
netdev_err(bgmac->net_dev, "Found poisoned packet at slot %d, DMA issue!\n",
ring->start);
put_page(virt_to_head_page(buf));
bgmac->net_dev->stats.rx_errors++;
break;
}
if (len > BGMAC_RX_ALLOC_SIZE) {
netdev_err(bgmac->net_dev, "Found oversized packet at slot %d, DMA issue!\n",
ring->start);
if (net_ratelimit())
netdev_err(bgmac->net_dev, "Found oversized packet at slot %d, DMA issue!\n",
ring->start);
put_page(virt_to_head_page(buf));
bgmac->net_dev->stats.rx_length_errors++;
bgmac->net_dev->stats.rx_errors++;