netdev - Re: [PATCH net-next v2 2/8] ipv4: icmp: Pass IPv4 control block structure as an argument to __icmp

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Message-ID: <CANn89iKir3_tS59i5ve=RKTgeOS6vRP_JLZyfkbFU0jRA_s_Zg@mail.gmail.com>
Date: Mon, 8 Sep 2025 00:55:02 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: Ido Schimmel <idosch@...dia.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org, 
	pabeni@...hat.com, horms@...nel.org, paul@...l-moore.com, dsahern@...nel.org, 
	petrm@...dia.com, linux-security-module@...r.kernel.org
Subject: Re: [PATCH net-next v2 2/8] ipv4: icmp: Pass IPv4 control block
 structure as an argument to __icmp_send()

On Mon, Sep 8, 2025 at 12:35 AM Ido Schimmel <idosch@...dia.com> wrote:
>
> __icmp_send() is used to generate ICMP error messages in response to
> various situations such as MTU errors (i.e., "Fragmentation Required")
> and too many hops (i.e., "Time Exceeded").
>
> The skb that generated the error does not necessarily come from the IPv4
> layer and does not always have a valid IPv4 control block in skb->cb.
>
> Therefore, commit 9ef6b42ad6fd ("net: Add __icmp_send helper.") changed
> the function to take the IP options structure as argument instead of
> deriving it from the skb's control block. Some callers of this function
> such as icmp_send() pass the IP options structure from the skb's control
> block as in these call paths the control block is known to be valid, but
> other callers simply pass a zeroed structure.
>
> A subsequent patch will need __icmp_send() to access more information
> from the IPv4 control block (specifically, the ifindex of the input
> interface). As a preparation for this change, change the function to
> take the IPv4 control block structure as an argument instead of the IP
> options structure. This makes the function similar to its IPv6
> counterpart that already takes the IPv6 control block structure as an
> argument.
>
> No functional changes intended.
>
> Reviewed-by: Petr Machata <petrm@...dia.com>
> Reviewed-by: David Ahern <dsahern@...nel.org>
> Signed-off-by: Ido Schimmel <idosch@...dia.com>

Reviewed-by: Eric Dumazet <edumazet@...gle.com>