netdev - RE: [Intel-wired-lan] [PATCH v1 iwl-next] igb: set skb hash type from RSS

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Message-ID: <IA3PR11MB898633484D0CB77105D1B9A1E597A@IA3PR11MB8986.namprd11.prod.outlook.com>
Date: Thu, 22 Jan 2026 07:33:23 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: Kohei Enju <kohei@...uk.jp>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
CC: "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, Andrew Lunn <andrew+netdev@...n.ch>, "David
 S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, "Jakub
 Kicinski" <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"kohei.enju@...il.com" <kohei.enju@...il.com>, Takashi Kozu
	<takkozu@...zon.com>
Subject: RE: [Intel-wired-lan] [PATCH v1 iwl-next] igb: set skb hash type from
 RSS_TYPE



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> Of Kohei Enju
> Sent: Monday, January 19, 2026 6:58 PM
> To: intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org
> Cc: Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@...el.com>; Andrew Lunn
> <andrew+netdev@...n.ch>; David S. Miller <davem@...emloft.net>; Eric
> Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo
> Abeni <pabeni@...hat.com>; kohei.enju@...il.com; Takashi Kozu
> <takkozu@...zon.com>; Kohei Enju <kohei@...uk.jp>
> Subject: [Intel-wired-lan] [PATCH v1 iwl-next] igb: set skb hash type
> from RSS_TYPE
> 
> igb always marks the RX hash as L3 regardless of RSS_TYPE in the
> advanced descriptor, which may indicate L4 (TCP/UDP) hash. This can
> trigger unnecessary SW hash recalculation and breaks toeplitz
> selftests.
> 
> Use RSS_TYPE from pkt_info to set the correct PKT_HASH_TYPE_*
> 
> Tested by toeplitz.py with the igb RSS key get/set patches applied as
> they are required for toeplitz.py (see Link below).
>  # ethtool -N $DEV rx-flow-hash udp4 sdfn  # ethtool -N $DEV rx-flow-
> hash udp6 sdfn  # python toeplitz.py | grep -E "^# Totals"
> 
> Without patch:
>  # Totals: pass:0 fail:12 xfail:0 xpass:0 skip:0 error:0
> 
> With patch:
>  # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0
> 
> Link: https://lore.kernel.org/intel-wired-lan/20260119084511.95287-5-
> takkozu@...zon.com/
> Signed-off-by: Kohei Enju <kohei@...uk.jp>
> ---
> If a Fixes tag is needed, it would be Fixes: 42bdf083fe70 ("net: igb
> calls skb_set_hash").
> 
> I'm not sure this qualifies as a fix, since the RX hash marking has
> been wrong for a long time without reported issues. So I'm leaning
> toward omitting Fixes.
> ---
>  drivers/net/ethernet/intel/igb/e1000_82575.h | 21
> ++++++++++++++++++++
>  drivers/net/ethernet/intel/igb/igb_main.c    | 18 +++++++++++++----
>  2 files changed, 35 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/e1000_82575.h
> b/drivers/net/ethernet/intel/igb/e1000_82575.h
> index 63ec253ac788..a855bc10f5d4 100644
> --- a/drivers/net/ethernet/intel/igb/e1000_82575.h
> +++ b/drivers/net/ethernet/intel/igb/e1000_82575.h
> @@ -87,6 +87,27 @@ union e1000_adv_rx_desc {
>  	} wb;  /* writeback */
>  };
> 
> +#define E1000_RSS_TYPE_NO_HASH		 0
> +#define E1000_RSS_TYPE_HASH_TCP_IPV4	 1
> +#define E1000_RSS_TYPE_HASH_IPV4	 2
> +#define E1000_RSS_TYPE_HASH_TCP_IPV6	 3
> +#define E1000_RSS_TYPE_HASH_IPV6_EX	 4
> +#define E1000_RSS_TYPE_HASH_IPV6	 5
> +#define E1000_RSS_TYPE_HASH_TCP_IPV6_EX	 6
> +#define E1000_RSS_TYPE_HASH_UDP_IPV4	 7
> +#define E1000_RSS_TYPE_HASH_UDP_IPV6	 8
> +#define E1000_RSS_TYPE_HASH_UDP_IPV6_EX	 9
> +
> +#define E1000_RSS_TYPE_MASK		GENMASK(3, 0) /* 4-bits (3:0)
> = mask 0x0F */
80columns violation, it's not critical, but I'd suggest just remove redundant comment
Otherwise, it smells like AI generated...
#define E1000_RSS_TYPE_MASK		GENMASK(3, 0)

Everything else looks fine.
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@...el.com>

> +
> +#define E1000_RSS_L4_TYPES_MASK	\
> +	(BIT(E1000_RSS_TYPE_HASH_TCP_IPV4)	| \
> +	 BIT(E1000_RSS_TYPE_HASH_TCP_IPV6)	| \
> +	 BIT(E1000_RSS_TYPE_HASH_TCP_IPV6_EX)	| \
> +	 BIT(E1000_RSS_TYPE_HASH_UDP_IPV4)	| \
> +	 BIT(E1000_RSS_TYPE_HASH_UDP_IPV6)	| \
> +	 BIT(E1000_RSS_TYPE_HASH_UDP_IPV6_EX))
> +
>  #define E1000_RXDADV_HDRBUFLEN_MASK      0x7FE0
>  #define E1000_RXDADV_HDRBUFLEN_SHIFT     5
>  #define E1000_RXDADV_STAT_TS             0x10000 /* Pkt was time
> stamped */
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c
> b/drivers/net/ethernet/intel/igb/igb_main.c
> index 8dab133296ca..ef0cbf532716 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -8824,10 +8824,20 @@ static inline void igb_rx_hash(struct igb_ring
> *ring,
>  			       union e1000_adv_rx_desc,
>  			       struct sk_buff *skb)
>  {
> -	if (ring->netdev->features & NETIF_F_RXHASH)
> -		skb_set_hash(skb,
> -			     le32_to_cpu(rx_desc->wb.lower.hi_dword.rss),
> -			     PKT_HASH_TYPE_L3);
> +	u16 rss_type;
> +
> +	if (!(ring->netdev->features & NETIF_F_RXHASH))
> +		return;
> +
> +	rss_type = le16_to_cpu(rx_desc->wb.lower.lo_dword.pkt_info) &
> +		   E1000_RSS_TYPE_MASK;
> +
> +	if (!rss_type)
> +		return;
> +
> +	skb_set_hash(skb, le32_to_cpu(rx_desc->wb.lower.hi_dword.rss),
> +		     (E1000_RSS_L4_TYPES_MASK & BIT(rss_type)) ?
> +		     PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
>  }
> 
>  /**
> --
> 2.51.0