Re: [PATCH net-next] net/tcp: Prevent inlining tcp_syn_ack_timeout()

[Paolo Abeni <pabeni@redhat.com>]

On 7/8/26 8:08 PM, Emil Tsalapatis wrote:
> The tcp_syn_ack_timeout() function gets inlined by Clang,
> preventing tracing. Since the call is not in the fast
> path, prevent it from being inlined.
> 
> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
> ---
>  net/ipv4/tcp_timer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
> index bf171b5e1eb3..f7215d53bbda 100644
> --- a/net/ipv4/tcp_timer.c
> +++ b/net/ipv4/tcp_timer.c
> @@ -748,7 +748,7 @@ static void tcp_write_timer(struct timer_list *t)
>  	sock_put(sk);
>  }
>  
> -void tcp_syn_ack_timeout(const struct request_sock *req)
> +noinline_for_tracing void tcp_syn_ack_timeout(const struct request_sock *req)
>  {
>  	struct net *net = read_pnet(&inet_rsk(req)->ireq_net);
>  

What's the point of tracing such function? It just increment a mib. If
you want to discriminate between TFO and non TFO syn ack timeout,
possibly adding another MIB counter and incrementing it in
tcp_fastopen_synack_timer() would be better???

/P