netdev - Re: [PATCH net-next v2 02/12] eth: mvpp2: implement new RSS context API

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Message-ID: <20240805142930.45a80248@kernel.org>
Date: Mon, 5 Aug 2024 14:29:30 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Edward Cree <ecree.xilinx@...il.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
 pabeni@...hat.com, dxu@...uu.xyz, przemyslaw.kitszel@...el.com,
 donald.hunter@...il.com, gal.pressman@...ux.dev, tariqt@...dia.com,
 willemdebruijn.kernel@...il.com, jdamato@...tly.com,
 marcin.s.wojtas@...il.com, linux@...linux.org.uk
Subject: Re: [PATCH net-next v2 02/12] eth: mvpp2: implement new RSS context
 API

On Mon, 5 Aug 2024 12:25:28 +0100 Edward Cree wrote:
> > mvpp2 doesn't have a key for the hash, it defaults to
> > an empty/previous indir table.  
> 
> Given that, should this be after patch #6?  So as to make it
>  obviously correct not to populate ethtool_rxfh_context_key(ctx)
>  with the default context's key.

It's a bit different. Patch 6 is about devices which have a key but 
the same key is used for all contexts. mvpp2 has no key at all
even for context 0 (get_rxfh_key_size is not defined).

> > @@ -5750,6 +5792,7 @@ static const struct net_device_ops mvpp2_netdev_ops = {
> >  
> >  static const struct ethtool_ops mvpp2_eth_tool_ops = {
> >  	.cap_rss_ctx_supported	= true,
> > +	.rxfh_max_context_id	= MVPP22_N_RSS_TABLES,  
> 
> Max ID is inclusive, not exclusive, so I think this should be
>  MVPP22_N_RSS_TABLES - 1?

I totally did check this before sending:

 * @rxfh_max_context_id: maximum (exclusive) supported RSS context ID.  If this
 *	is zero then the core may choose any (nonzero) ID, otherwise the core
 *	will only use IDs strictly less than this value, as the @rss_context
 *	argument to @create_rxfh_context and friends.

But you're right, the code acts as if it was inclusive :S

Coincidentally, the default also appears exclusive:

	u32 limit = ops->rxfh_max_context_id ?: U32_MAX;

U32_MAX can't be used, it has special meaning:

#define ETH_RXFH_CONTEXT_ALLOC		0xffffffff

These seem like net-worthy fixes, no?