[PATCH net 1/6] igc: Fix RX HW timestamp reporting when NET_RX_BUSY_POLL is disabled
flat view
WARM1d
REVIEWED: 2 (0M)
From: Tony Nguyen <anthony.l.nguyen@intel.com>
Date: 2026-10-01 22:24:59
Also in:
bpf, stable
Subsystem:
intel ethernet drivers, networking drivers, the rest · Maintainers:
Tony Nguyen, Przemek Kitszel, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
2 review trailers.
From: Ding Meng <redacted>
When CONFIG_NET_RX_BUSY_POLL is deactivated, fetching RX HW timestamps
from the NIC no longer works as expected, often resulting in incorrect
or negative values such as "HW raw -121948.050407424".
This occurs because disabling CONFIG_NET_RX_BUSY_POLL disables the
SKB NAPI mapping in __skb_mark_napi_id(). Consequently, get_timestamp()
fails to perform its driver lookup, and the igc driver's struct
net_device_ops::ndo_get_tstamp is never invoked.
Instead, get_timestamp() falls back to use shhwtstamps(skb)->hwtstamp,
a field that the driver has not populated. This results in incorrect
timestamps.
Fix this by populating the hwtstamp field with the correct timestamp
in the default timer when CONFIG_NET_RX_BUSY_POLL is disabled.
The "igc_adapter" is passed to igc_construct_skb() to enable
igc_ptp_rx_pktstamp() to access the necessary adapter details for
adjusting the timestamp.
Test case:
Disable CONFIG_NET_RX_BUSY_POLL.
Sender:
# tools/testing/selftests/net/timestamping en0 \
SOF_TIMESTAMPING_TX_HARDWARE PTPV2 IP_MULTICAST_LOOP
Receiver:
# tools/testing/selftests/net/timestamping en0 \
SOF_TIMESTAMPING_RX_HARDWARE SOF_TIMESTAMPING_RAW_HARDWARE PTPV2
Before patch, receiver prints
HW raw -121948.050407424
After patch, receiver prints
HW raw 1760648763.746974064
Fixes: 069b142f5819 ("igc: Add support for PTP .getcyclesx64()")
Cc: stable@vger.kernel.org
Co-developed-by: Florian Bezdeka <redacted>
Signed-off-by: Florian Bezdeka <redacted>
Signed-off-by: Ding Meng <redacted>
Reviewed-by: Aleksandr Loktionov <redacted>
Reviewed-by: Piotr Kwapulinski <redacted>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
drivers/net/ethernet/intel/igc/igc_main.c | 41 ++++++++++++++++-------
1 file changed, 29 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 1fb5f3cbe93c..95f7747b347b 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c@@ -1989,7 +1989,29 @@ static struct sk_buff *igc_build_skb(struct igc_ring *rx_ring, return skb; } -static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring, +static void igc_construct_skb_timestamps(struct igc_adapter *adapter, + struct sk_buff *skb, + struct igc_xdp_buff *ctx) +{ +#ifndef CONFIG_NET_RX_BUSY_POLL + struct igc_inline_rx_tstamps *tstamps; +#endif + + if (!ctx->rx_ts) + return; + +#ifndef CONFIG_NET_RX_BUSY_POLL + tstamps = ctx->rx_ts; + skb_hwtstamps(skb)->hwtstamp = igc_ptp_rx_pktstamp(adapter, + tstamps->timer0); +#else + skb_shinfo(skb)->tx_flags |= SKBTX_HW_TSTAMP_NETDEV; + skb_hwtstamps(skb)->netdev_data = ctx->rx_ts; +#endif +} + +static struct sk_buff *igc_construct_skb(struct igc_adapter *adapter, + struct igc_ring *rx_ring, struct igc_rx_buffer *rx_buffer, struct igc_xdp_buff *ctx) {
@@ -2010,10 +2032,7 @@ static struct sk_buff *igc_construct_skb(struct igc_ring *rx_ring, if (unlikely(!skb)) return NULL; - if (ctx->rx_ts) { - skb_shinfo(skb)->tx_flags |= SKBTX_HW_TSTAMP_NETDEV; - skb_hwtstamps(skb)->netdev_data = ctx->rx_ts; - } + igc_construct_skb_timestamps(adapter, skb, ctx); /* Determine available headroom for copy */ headlen = size;
@@ -2683,7 +2702,7 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget) else if (ring_uses_build_skb(rx_ring)) skb = igc_build_skb(rx_ring, rx_buffer, &ctx.xdp); else - skb = igc_construct_skb(rx_ring, rx_buffer, &ctx); + skb = igc_construct_skb(adapter, rx_ring, rx_buffer, &ctx); /* exit if we failed to retrieve a buffer */ if (!xdp_res && !skb) {
@@ -2735,7 +2754,8 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget) return total_packets; } -static struct sk_buff *igc_construct_skb_zc(struct igc_ring *ring, +static struct sk_buff *igc_construct_skb_zc(struct igc_adapter *adapter, + struct igc_ring *ring, struct igc_xdp_buff *ctx) { struct xdp_buff *xdp = &ctx->xdp;
@@ -2757,10 +2777,7 @@ static struct sk_buff *igc_construct_skb_zc(struct igc_ring *ring, __skb_pull(skb, metasize); } - if (ctx->rx_ts) { - skb_shinfo(skb)->tx_flags |= SKBTX_HW_TSTAMP_NETDEV; - skb_hwtstamps(skb)->netdev_data = ctx->rx_ts; - } + igc_construct_skb_timestamps(adapter, skb, ctx); return skb; }
@@ -2772,7 +2789,7 @@ static void igc_dispatch_skb_zc(struct igc_q_vector *q_vector, struct igc_ring *ring = q_vector->rx.ring; struct sk_buff *skb; - skb = igc_construct_skb_zc(ring, ctx); + skb = igc_construct_skb_zc(q_vector->adapter, ring, ctx); if (!skb) { ring->rx_stats.alloc_failed++; set_bit(IGC_RING_FLAG_RX_ALLOC_FAILED, &ring->flags);
--
2.47.1