[linux-next:master 7868/8410] net/netfilter/core.c:353:20: error: unused function 'nf_egress_hook'

[linux-next:master 7868/8410] net/netfilter/core.c:353:20: error: unused function 'nf_egress_hook'

[kernel test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   7c832d2f9b959e3181370c8b0dacaf9efe13fc05
commit: 42df6e1d221dddc0f2acf2be37e68d553ad65f96 [7868/8410] netfilter: Introduce egress hook
config: x86_64-buildonly-randconfig-r003-20211015 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 6069a6a5049497a32a50a49661c2f4169078bdba)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=42df6e1d221dddc0f2acf2be37e68d553ad65f96
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout 42df6e1d221dddc0f2acf2be37e68d553ad65f96
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   net/netfilter/core.c:344:20: error: unused function 'nf_ingress_hook' [-Werror,-Wunused-function]
   static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
                      ^
>> net/netfilter/core.c:353:20: error: unused function 'nf_egress_hook' [-Werror,-Wunused-function]
   static inline bool nf_egress_hook(const struct nf_hook_ops *reg, int pf)
                      ^
   2 errors generated.


vim +/nf_egress_hook +353 net/netfilter/core.c

   343	
 > 344	static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
   345	{
   346		if ((pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) ||
   347		    (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS))
   348			return true;
   349	
   350		return false;
   351	}
   352	
 > 353	static inline bool nf_egress_hook(const struct nf_hook_ops *reg, int pf)
   354	{
   355		return pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_EGRESS;
   356	}
   357	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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[PATCH nf-next] netfilter: core: Fix clang warnings about unused static inlines

[Lukas Wunner]

Unlike gcc, clang warns about unused static inlines that are not in an
include file:

  net/netfilter/core.c:344:20: error: unused function 'nf_ingress_hook' [-Werror,-Wunused-function]
  static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
                     ^
  net/netfilter/core.c:353:20: error: unused function 'nf_egress_hook' [-Werror,-Wunused-function]
  static inline bool nf_egress_hook(const struct nf_hook_ops *reg, int pf)
                     ^

According to commit 6863f5643dd7 ("kbuild: allow Clang to find unused
static inline functions for W=1 build"), the proper resolution is to
mark the affected functions as __maybe_unused.  An alternative approach
would be to move them to include/linux/netfilter_netdev.h, but since
Pablo didn't do that in commit ddcfa710d40b ("netfilter: add
nf_ingress_hook() helper function"), I'm guessing __maybe_unused is
preferred.

This fixes both the warning introduced by Pablo in v5.10 as well as the
one recently introduced by myself with commit 42df6e1d221d ("netfilter:
Introduce egress hook").

Fixes: ddcfa710d40b ("netfilter: add nf_ingress_hook() helper function")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v5.10+
---
 net/netfilter/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 3a32a813fcde..6dec9cd395f1 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -341,7 +341,8 @@ static int nf_ingress_check(struct net *net, const struct nf_hook_ops *reg,
 	return 0;
 }
 
-static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
+static inline bool __maybe_unused nf_ingress_hook(const struct nf_hook_ops *reg,
+						  int pf)
 {
 	if ((pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) ||
 	    (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS))
@@ -350,7 +351,8 @@ static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
 	return false;
 }
 
-static inline bool nf_egress_hook(const struct nf_hook_ops *reg, int pf)
+static inline bool __maybe_unused nf_egress_hook(const struct nf_hook_ops *reg,
+						 int pf)
 {
 	return pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_EGRESS;
 }
-- 
2.31.1

Re: [PATCH nf-next] netfilter: core: Fix clang warnings about unused static inlines

[Pablo Neira Ayuso]

On Sat, Oct 16, 2021 at 10:13:27AM +0200, Lukas Wunner wrote:
> Unlike gcc, clang warns about unused static inlines that are not in an
> include file:
> 
>   net/netfilter/core.c:344:20: error: unused function 'nf_ingress_hook' [-Werror,-Wunused-function]
>   static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
>                      ^
>   net/netfilter/core.c:353:20: error: unused function 'nf_egress_hook' [-Werror,-Wunused-function]
>   static inline bool nf_egress_hook(const struct nf_hook_ops *reg, int pf)
>                      ^
> 
> According to commit 6863f5643dd7 ("kbuild: allow Clang to find unused
> static inline functions for W=1 build"), the proper resolution is to
> mark the affected functions as __maybe_unused.  An alternative approach
> would be to move them to include/linux/netfilter_netdev.h, but since
> Pablo didn't do that in commit ddcfa710d40b ("netfilter: add
> nf_ingress_hook() helper function"), I'm guessing __maybe_unused is
> preferred.
> 
> This fixes both the warning introduced by Pablo in v5.10 as well as the
> one recently introduced by myself with commit 42df6e1d221d ("netfilter:
> Introduce egress hook").

Applied, thanks.