netdev - Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP

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Message-ID: <20240228064859.423a7c5e@kernel.org>
Date: Wed, 28 Feb 2024 06:48:59 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Petr Machata <petrm@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 <netdev@...r.kernel.org>, Ido Schimmel <idosch@...dia.com>, David Ahern
 <dsahern@...nel.org>, <mlxsw@...dia.com>
Subject: Re: [PATCH net-next 2/7] net: nexthop: Add NHA_OP_FLAGS

On Wed, 28 Feb 2024 11:50:33 +0100 Petr Machata wrote:
> > Why bitfiled? You never use the mask.
> > bitfield gives you the ability to do RMW "atomically" on object fields.
> > For op flags I don't think it makes much sense.  
> 
> Mostly because we get flag validation for free, whereas it would need to
> be hand-rolled for u32. 

NLA_POLICY_MASK() ?

> But also I don't know what will be useful in the
> future. It would be silly to have to add another flags attribute as
> bitfield because this time we actually care about toggling single bits
> of an object.

IDK how you can do RMW on operation flags, that only makes sense if
you're modifying something. Besides you're not using BITFIELD right,
you're ignoring the mask completely now.