linux-kernel - Re: [PATCH] net: linearizing skb when downgrade gso

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Message-Id: <20240712081724.95738-1-dracodingfly@gmail.com>
Date: Fri, 12 Jul 2024 16:17:24 +0800
From: Fred Li <dracodingfly@...il.com>
To: willemdebruijn.kernel@...il.com
Cc: bpf@...r.kernel.org,
	herbert@...dor.apana.org.au,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH] net: linearizing skb when downgrade gso_size

> No need for ternary statement.
> 
> Instead of the complex test in skb_is_nonsg, can we just assume that
> alignment will be off if having frag_list and changing gso_size.
> 
> The same will apply to bpf_skb_net_shrink too.

increase gso_size may be no problem and we can use BPF_F_ADJ_ROOM_FIXED_GSO
to avoid update gso_size when shrink.

> 
> Not sure that it is okay to linearize inside a BPF helper function.
> Hopefully bpf experts can chime in on that.

Thanks

Fred Li