Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Eric Dumazet <> | Date | Mon, 6 Nov 2023 16:52:52 +0100 | Subject | Re: [PATCH net v2] tcp: Fix -Wc23-extensions in tcp_options_write() |
| |
On Mon, Nov 6, 2023 at 4:36 PM Nathan Chancellor <nathan@kernel.org> wrote: > > Clang warns (or errors with CONFIG_WERROR=y) when CONFIG_TCP_AO is set: > > net/ipv4/tcp_output.c:663:2: error: label at end of compound statement is a C23 extension [-Werror,-Wc23-extensions] > 663 | } > | ^ > 1 error generated. > > On earlier releases (such as clang-11, the current minimum supported > version for building the kernel) that do not support C23, this was a > hard error unconditionally: > > net/ipv4/tcp_output.c:663:2: error: expected statement > } > ^ > 1 error generated. > > While adding a semicolon after the label would resolve this, it is more > in line with the kernel as a whole to refactor this block into a > standalone function, which means the goto a label construct can just be > replaced with a simple return. Do so to resolve the warning. > > Closes: https://github.com/ClangBuiltLinux/linux/issues/1953 > Fixes: 1e03d32bea8e ("net/tcp: Add TCP-AO sign to outgoing packets") > Signed-off-by: Nathan Chancellor <nathan@kernel.org> > --- > Please let me know if this function should have a different name. I > think I got all the changes of the function shuffle correct but some > testing would be appreciated. > > Changes in v2: > - Break out problematic block into its own function so that goto can be > replaced with a simple return, instead of the simple semicolon > approach of v1 (Christoph) > - Link to v1: https://lore.kernel.org/r/20231031-tcp-ao-fix-label-in-compound-statement-warning-v1-1-c9731d115f17@kernel.org > --- > net/ipv4/tcp_output.c | 69 ++++++++++++++++++++++++++++----------------------- > 1 file changed, 38 insertions(+), 31 deletions(-) > > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > index 0d8dd5b7e2e5..3f8dc74fbf40 100644 > --- a/net/ipv4/tcp_output.c > +++ b/net/ipv4/tcp_output.c > @@ -601,6 +601,43 @@ static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, > } > #endif > > +static void process_tcp_ao_options(struct tcp_sock *tp, > + const struct tcp_request_sock *tcprsk, > + struct tcp_out_options *opts, > + struct tcp_out_options *opts,
ptr has a different type than in the caller, this is a bit confusing
I would use
static __be32 * process_tcp_ao_options(struct tcp_sock *tp, const struct tcp_request_sock *tcprsk, struct tcp_out_options *opts,struct tcp_key *key, __be32 *ptr)
> +{ > +#ifdef CONFIG_TCP_AO > + u8 maclen = tcp_ao_maclen(key->ao_key); > + > + if (tcprsk) { > + u8 aolen = maclen + sizeof(struct tcp_ao_hdr); > + > + *(*ptr)++ = htonl((TCPOPT_AO << 24) | (aolen << 16) | > + (tcprsk->ao_keyid << 8) | > + (tcprsk->ao_rcv_next));
*ptr++ = ...
(and in all other *ptr uses in this helper)
> + } else { > + struct tcp_ao_key *rnext_key; > + struct tcp_ao_info *ao_info; > + > + ao_info = rcu_dereference_check(tp->ao_info, > + lockdep_sock_is_held(&tp->inet_conn.icsk_inet.sk)); > + rnext_key = READ_ONCE(ao_info->rnext_key); > + if (WARN_ON_ONCE(!rnext_key)) > + return; > + *(*ptr)++ = htonl((TCPOPT_AO << 24) | > + (tcp_ao_len(key->ao_key) << 16) | > + (key->ao_key->sndid << 8) | > + (rnext_key->rcvid)); > + } > + opts->hash_location = (__u8 *)(*ptr); > + *ptr += maclen / sizeof(**ptr); > + if (unlikely(maclen % sizeof(**ptr))) { > + memset(*ptr, TCPOPT_NOP, sizeof(**ptr)); > + (*ptr)++; > + } > +#endif
return ptr; +} > + > /* Write previously computed TCP options to the packet. > * > * Beware: Something in the Internet is very sensitive to the ordering of > @@ -629,37 +666,7 @@ static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp, > opts->hash_location = (__u8 *)ptr; > ptr += 4; > } else if (tcp_key_is_ao(key)) { > -#ifdef CONFIG_TCP_AO > - u8 maclen = tcp_ao_maclen(key->ao_key); > - > - if (tcprsk) { > - u8 aolen = maclen + sizeof(struct tcp_ao_hdr); > - > - *ptr++ = htonl((TCPOPT_AO << 24) | (aolen << 16) | > - (tcprsk->ao_keyid << 8) | > - (tcprsk->ao_rcv_next)); > - } else { > - struct tcp_ao_key *rnext_key; > - struct tcp_ao_info *ao_info; > - > - ao_info = rcu_dereference_check(tp->ao_info, > - lockdep_sock_is_held(&tp->inet_conn.icsk_inet.sk)); > - rnext_key = READ_ONCE(ao_info->rnext_key); > - if (WARN_ON_ONCE(!rnext_key)) > - goto out_ao; > - *ptr++ = htonl((TCPOPT_AO << 24) | > - (tcp_ao_len(key->ao_key) << 16) | > - (key->ao_key->sndid << 8) | > - (rnext_key->rcvid)); > - } > - opts->hash_location = (__u8 *)ptr; > - ptr += maclen / sizeof(*ptr); > - if (unlikely(maclen % sizeof(*ptr))) { > - memset(ptr, TCPOPT_NOP, sizeof(*ptr)); > - ptr++; > - } > -out_ao: > -#endif > + process_tcp_ao_options(tp, tcprsk, opts, key, &ptr);
ptr = process_tcp_ao_options(tp, tcprsk, opts, key, ptr);
> } > if (unlikely(opts->mss)) { > *ptr++ = htonl((TCPOPT_MSS << 24) | > > --- > base-commit: c1ed833e0b3b7b9edc82b97b73b2a8a10ceab241 > change-id: 20231031-tcp-ao-fix-label-in-compound-statement-warning-ebd6c9978498 > > Best regards, > -- > Nathan Chancellor <nathan@kernel.org> >
| ![\](/images/icornerr.gif) |