netdev - Re: [ovs-dev] [PATCH net-next] net: Add options as a flexible array to struct ip_tunnel

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Message-ID: <f12c1f1e-3ae8-4cd8-b727-61c35b8ed9ce@nvidia.com>
Date: Tue, 11 Feb 2025 17:38:31 +0200
From: Gal Pressman <gal@...dia.com>
To: Ilya Maximets <i.maximets@....org>, netdev@...r.kernel.org,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Andrew Lunn <andrew+netdev@...n.ch>
Cc: dev@...nvswitch.org, "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 Jiri Pirko <jiri@...nulli.us>, Jamal Hadi Salim <jhs@...atatu.com>,
 Kees Cook <kees@...nel.org>, David Ahern <dsahern@...nel.org>,
 Yotam Gigi <yotam.gi@...il.com>, Tariq Toukan <tariqt@...dia.com>,
 linux-hardening@...r.kernel.org, Simon Horman <horms@...nel.org>,
 Cong Wang <xiyou.wangcong@...il.com>, Cosmin Ratiu <cratiu@...dia.com>
Subject: Re: [ovs-dev] [PATCH net-next] net: Add options as a flexible array
 to struct ip_tunnel_info

On 09/02/2025 22:16, Ilya Maximets wrote:
> Ideally we would have a proper union with all the potential option types
> instead of this hacky construct.  But if that's not the the way to go, then
> 8 bytes may indeed be the way, as it is the maximum guaranteed alignment
> for allocations and the current alignment of the structure.
> 
> But I'll leave this for others to weigh in.

Thank you Ilya.

Unless anyone has a better idea, I'm going to add an explicit alignment
to the options field, that would keep the struct layout as it was before
this patch.