Re: [PATCH net] mlxsw: spectrum_ptp: Fix napi_gro_receive() call from GC workqueue context
From: Petr Machata <petrm@nvidia.com>
Date: 2026-09-03 09:30:59
Taylor Bates [off-list ref] writes:
This patch adds an ingress-delivery helper for the PTP packet_finish()
path that calls netif_receive_skb() instead of napi_gro_receive().
netif_receive_skb(), unlike napi_gro_receive(), can be called from outside
of the NAPI instance's poll context, which can occur at the call site for
this path. RX stats accounting and the skb->dev assignment are still
preserved; the only change is the delivery call itself.
This removes GRO batching for any PTP event traffic received by the mlxsw
trap, but given the relatively low volume of traffic characteristic of the
protocol, and impact limited to only Spectrum-1 ASICs, this is an
acceptable solution.
Fixes: 1ba06ca96ca2 ("mlxsw: Switch to napi_gro_receive()")
Signed-off-by: Taylor Bates <redacted>Reviewed-by: Petr Machata <petrm@nvidia.com>
quoted hunk ↗ jump to hunk
--- .../ethernet/mellanox/mlxsw/spectrum_ptp.c | 34 ++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-)diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c index 9939749c47bc..9c5862f4e16a 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c@@ -572,6 +572,38 @@ mlxsw_sp1_ptp_unmatched_remove(struct mlxsw_sp *mlxsw_sp,
+static void mlxsw_sp1_ptp_rx_finish(struct mlxsw_sp_port *mlxsw_sp_port,
+ struct sk_buff *skb)
+{
+ struct mlxsw_sp_port_pcpu_stats *pcpu_stats;
+
+ skb->dev = mlxsw_sp_port->dev;
+
+ pcpu_stats = this_cpu_ptr(mlxsw_sp_port->pcpu_stats);
+ u64_stats_update_begin(&pcpu_stats->syncp);
+ pcpu_stats->rx_packets++;
+ pcpu_stats->rx_bytes += skb->len;
+ u64_stats_update_end(&pcpu_stats->syncp);
+
+ skb->protocol = eth_type_trans(skb, skb->dev);
+ netif_receive_skb(skb);
+}Not entirely happy with inlining like this, but there are at least two copies of this block already. We could factor out the commonality at some point, but the code is mechanical and I think it's OK.
+ /* This function is called in the following scenarios: * * 1) When a packet is matched with its timestamp.