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From: Jakub Kicinski <kuba@kernel.org>
To: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: netdev-bot+sashiko@kernel.org, andrew+netdev@lunn.ch,
	davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
	horms@kernel.org, mcoquelin.stm32@gmail.com,
	alexandre.torgue@foss.st.com, linux@armlinux.org.uk,
	lorenzo.bianconi@oss.qualcomm.com, nb@tipi-net.de,
	jitendra.vegiraju@broadcom.com, thomas.petazzoni@bootlin.com,
	alexis.lothore@bootlin.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-stm32@st-md-mailman.stormreply.com, pbrobinson@gmail.com,
	joe@dama.to
Subject: Re: [PATCH net-next v3 1/3] net: rss: Require indir table size or hash key size to support RSS
Date: Tue, 6 Oct 2026 16:33:49 -0700	[thread overview]
Message-ID: <20261006163349.61c738e8@kernel.org> (raw)
In-Reply-To: <d6e61c8b-cd3d-43fe-b4ac-19ff5d790b0f@bootlin.com>

On Tue, 6 Oct 2026 09:59:29 +0200 Maxime Chevallier wrote:
> > [Severity: Medium]
> > rss_get_data_alloc() is shared by RSS_GET, RSS_SET and RSS_CREATE. Does
> > this drop flow-hash reporting for devices that have ->get_rxfh but report
> > 0/0 sizes?  
> 
> Yes it does, that's the intended behaviour here. RSS bits are all optional,
> but does it make sense to report hashing params when the indirection table
> is size 0 and key len is 0 ?

Not sure if there's an implementation in the tree but 
it's possible to implement poor man's RSS on strict
power-of-2 queue set with some hashing built into the
Rx engine, without a key. We'd still want to control
which fields are hashed in this case.

In the Netlink API we combine the two so we'd break this?

  reply	other threads:[~2026-10-06 23:33 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-02 14:28 [PATCH net-next v3 0/3] net: rss: Consider RSS not supported when key and indir sizes are 0 Maxime Chevallier
2026-10-02 14:28 ` [PATCH net-next v3 1/3] net: rss: Require indir table size or hash key size to support RSS Maxime Chevallier
2026-10-02 14:59   ` Nicolai Buchwitz
2026-10-05 14:29   ` netdev-bot+sashiko
2026-10-06  7:59     ` Maxime Chevallier
2026-10-06 23:33       ` Jakub Kicinski [this message]
2026-10-02 14:28 ` [PATCH net-next v3 2/3] net: stmmac: Introduce a helper to check RSS support Maxime Chevallier
2026-10-02 15:00   ` Nicolai Buchwitz
2026-10-02 14:28 ` [PATCH net-next v3 3/3] net: stmmac: Don't set or get RSS parameters when not supported Maxime Chevallier
2026-10-02 15:00   ` Nicolai Buchwitz
2026-10-05 14:29   ` netdev-bot+sashiko

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