[PATCH net-next v2 2/8] ipv4: icmp: Pass IPv4 control block structure as an argument to __icmp_send()

[Eric Dumazet]

On Mon, Sep 8, 2025 at 12:35 AM Ido Schimmel <idosch at nvidia.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 at nvidia.com>
> Reviewed-by: David Ahern <dsahern at kernel.org>
> Signed-off-by: Ido Schimmel <idosch at nvidia.com>

Reviewed-by: Eric Dumazet <edumazet at google.com>