netdev - Re: [PATCH] skbuff: skb_segment, Update nfrags after calling zero copy functions

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Message-ID: <20230829065010.GO4091703@medusa>
Date: Mon, 28 Aug 2023 23:50:10 -0700
From: Mohamed Khalfella <mkhalfella@...estorage.com>
To: willemjdebruijn <willemdebruijn.kernel@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemb@...gle.com>,
	Alexander Duyck <alexanderduyck@...com>,
	David Howells <dhowells@...hat.com>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	Kees Cook <keescook@...omium.org>,
	"open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	"open list:BPF [MISC]" <bpf@...r.kernel.org>
Subject: Re: [PATCH] skbuff: skb_segment, Update nfrags after calling zero
 copy functions

On 2023-08-28 21:18:16 -0700, willemjdebruijn wrote:
> Small point: nfrags is not the only state that needs to be refreshed
> after a fags realloc, also frag.

I am new to this code. Can you help me understand why frag needs to be
updated too? My reading of this code is that frag points to frags array
in shared info. As long as shared info pointer remain the same frag
pointer should remain valid.

Am I missing something?
> 
> Thanks for the report. I'm traveling likely without internet until the
> weekend. Apologies if it takes a while for me to follow up.
No problem. Thanks for the quick response!