Re: [PATCH net] tcp: Fix -Wc23-extensions in tcp_options_write()
From: Nathan Chancellor <nathan@kernel.org>
Date: 2023-11-03 16:53:18
Also in:
linux-patches, lkml, llvm
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
Hi Christoph, On Fri, Nov 03, 2023 at 01:22:05AM -0700, Christoph Hellwig wrote:
On Tue, Oct 31, 2023 at 01:23:35PM -0700, Nathan Chancellor wrote:quoted
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. Add a semicolon after the label to create an empty statement, which resolves the warning or error for all compilers.Can you please just split the A0 handlig into a separate helper, which shuld make the whole thing a lot cleaner?
Is something like this (I think I got all the pointer manipulation correct...) what you had in mind? I am happy to send that as a v2 if the netdev folks would prefer it over this small change (along with some guidance about the function name, if it should be something different). Cheers, Nathan
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f558c054cf6e..6f2a5e3bb7b3 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_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)); + } 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 +} + /* 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); } if (unlikely(opts->mss)) { *ptr++ = htonl((TCPOPT_MSS << 24) |