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 <[email protected]>
---
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_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) |
---
base-commit: c1ed833e0b3b7b9edc82b97b73b2a8a10ceab241
change-id: 20231031-tcp-ao-fix-label-in-compound-statement-warning-ebd6c9978498
Best regards,
--
Nathan Chancellor <[email protected]>
On Mon, Nov 6, 2023 at 4:36 PM Nathan Chancellor <[email protected]> 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 <[email protected]>
> ---
> 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 <[email protected]>
>
On Mon, Nov 06, 2023 at 04:52:52PM +0100, Eric Dumazet wrote:
> On Mon, Nov 6, 2023 at 4:36 PM Nathan Chancellor <[email protected]> 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 <[email protected]>
> > ---
> > 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)
Ah, this suggestion is much better, thanks. I'll make this adjustment
and send a v3 later today in case others have any suggested changes (I
know netdev prefers waiting 24 hours for another revision but I'd like
to get this warning cleared up by -rc1 so it does not proliferate into
other trees and I sent v1 almost a week ago).
> > +{
> > +#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 <[email protected]>
> >
On Mon, 6 Nov 2023 08:58:06 -0700 Nathan Chancellor wrote:
> Ah, this suggestion is much better, thanks. I'll make this adjustment
> and send a v3 later today in case others have any suggested changes (I
> know netdev prefers waiting 24 hours for another revision but I'd like
> to get this warning cleared up by -rc1 so it does not proliferate into
> other trees and I sent v1 almost a week ago).
Definitely, sorry about the delay, feel free to post v3 ASAP.
On Mon, Nov 06, 2023 at 12:52:57PM -0800, Jakub Kicinski wrote:
> On Mon, 6 Nov 2023 08:58:06 -0700 Nathan Chancellor wrote:
> > Ah, this suggestion is much better, thanks. I'll make this adjustment
> > and send a v3 later today in case others have any suggested changes (I
> > know netdev prefers waiting 24 hours for another revision but I'd like
> > to get this warning cleared up by -rc1 so it does not proliferate into
> > other trees and I sent v1 almost a week ago).
>
> Definitely, sorry about the delay, feel free to post v3 ASAP.
Done, thanks Jakub!
https://lore.kernel.org/20231106-tcp-ao-fix-label-in-compound-statement-warning-v3-1-b54a64602a85@kernel.org/
Cheers,
Nathan