Re: [PATCH net v3] tcp: check skb is non-NULL in tcp_rto_delta_us()

[Josh Hunt]

On 9/19/24 2:05 AM, Paolo Abeni wrote:
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> On 9/10/24 21:08, Josh Hunt wrote:
> > diff --git a/include/net/tcp.h b/include/net/tcp.h
> > index 2aac11e7e1cc..196c148fce8a 100644
> > --- a/include/net/tcp.h
> > +++ b/include/net/tcp.h
> > @@ -2434,9 +2434,26 @@ static inline s64 tcp_rto_delta_us(const struct 
> > sock *sk)
> >   {
> >       const struct sk_buff *skb = tcp_rtx_queue_head(sk);
> >       u32 rto = inet_csk(sk)->icsk_rto;
> > -    u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + 
> > jiffies_to_usecs(rto);
> > -    return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
> > +    if (likely(skb)) {
> > +        u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + 
> > jiffies_to_usecs(rto);
> > +
> > +        return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
> > +    } else {
> > +        WARN_ONCE(1,
> > +            "rtx queue emtpy: "
> > +            "out:%u sacked:%u lost:%u retrans:%u "
> > +            "tlp_high_seq:%u sk_state:%u ca_state:%u "
> > +            "advmss:%u mss_cache:%u pmtu:%u\n",
> > +            tcp_sk(sk)->packets_out, tcp_sk(sk)->sacked_out,
> > +            tcp_sk(sk)->lost_out, tcp_sk(sk)->retrans_out,
> > +            tcp_sk(sk)->tlp_high_seq, sk->sk_state,
> > +            inet_csk(sk)->icsk_ca_state,
> > +            tcp_sk(sk)->advmss, tcp_sk(sk)->mss_cache,
> > +            inet_csk(sk)->icsk_pmtu_cookie);
>
> As the underlying issue here share the same root cause as the one 
> covered by the WARN_ONCE() in tcp_send_loss_probe(), I'm wondering if it 
> would make sense do move the info dumping in a common helper, so that we 
> get the verbose warning on either cases.
>
> Thanks,
>
> Paolo

Thanks for the review Paolo. Sorry for the delay in replying I was OOO. 
I can send a follow-up commit to create a common helper.

Josh