Issue with module compilation on Centos 7 kernel-lt-5.4 from elrepo

[gavrilov-i]

Hello, recently we've updated kernel from the kernel-lt-4.4 tree to kernel-lt-5.4 (from elrepo), and now we are experiencing issue with ipt_NETFLOW compilation:
Here is ./configure output with module/kernel/iptables versions

Module version: 2.5.1-11-g5405927-dirty
Kernel version: 5.4.108-1.el7.elrepo.x86_64 (requested)
Kernel sources: /lib/modules/5.4.108-1.el7.elrepo.x86_64/build (found)
Checking for presence of include/linux/netfilter.h... Yes
netfilter.h uses CONFIG_NF_NAT_NEEDED... No
Checking for presence of include/linux/llist.h... Yes
Checking for presence of include/linux/grsecurity.h... No
Iptables binary version: 1.4.21 (detected from /sbin/iptables)
pkg-config for version 1.4.21 exists: Yes
Check for working gcc: Yes (gcc)
Checking for presence of xtables.h... Yes (using pkg-config)
Iptables include flags:   (pkg-config)
Iptables module path: /usr/lib64/xtables (pkg-config)
Searching for net-snmp-config... No.
Searching for net-snmp agent... Yes.
! You have net-snmp agent but not development package.
! net-snmp agent will not be built, to fix:
!   run:  yum install net-snmp-devel
Checking for DKMS... Yes.
! You are already have module installed via DKMS
!   it will be uninstalled on 'make install' and
!   current version of module installed afterwards.
! Use --disable-dkms option if don't want this.
Creating Makefile.. done.

  If you need some options enabled run ./configure --help
  Now run: make all install

and part of the make output (there are vast of output, but the most of it points to the similar errors):

Test symbol xt_family linux/netfilter_ipv4/ip_tables.h  undeclared
Error: unexpected error from compiler
make -s -B -C /lib/modules/5.4.108-1.el7.elrepo.x86_64/build M=/usr/src/ipt-netflow/cc-test-build modules
In file included from <command-line>:0:0:
./arch/x86/include/asm/page_64.h: In function 'clear_page':
././include/linux/compiler_types.h:214:24: error: expected '(' before '__inline'
 #define asm_inline asm __inline
                        ^
./arch/x86/include/asm/alternative.h:256:2: note: in expansion of macro 'asm_inline'
  asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
  ^
./arch/x86/include/asm/page_64.h:49:2: note: in expansion of macro 'alternative_call_2'
  alternative_call_2(clear_page_orig,
  ^
In file included from ./arch/x86/include/asm/barrier.h:5:0,
                 from ./include/linux/compiler.h:323,
                 from ./include/linux/export.h:42,
                 from ./include/linux/linkage.h:7,
                 from ./include/linux/kernel.h:8,
                 from ./include/linux/list.h:9,
                 from ./include/linux/module.h:9,
                 from /usr/src/ipt-netflow/cc-test-build/test.c:1:
./arch/x86/include/asm/alternative.h:128:2: error: expected identifier or '(' before string constant
  "# ALT: oldinstr2\n"         \
  ^
./arch/x86/include/asm/alternative.h:168:2: note: in expansion of macro 'OLDINSTR_2'
  OLDINSTR_2(oldinstr, 1, 2)     \
  ^
./arch/x86/include/asm/alternative.h:256:23: note: in expansion of macro 'ALTERNATIVE_2'
  asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
                       ^
./arch/x86/include/asm/page_64.h:49:2: note: in expansion of macro 'alternative_call_2'
  alternative_call_2(clear_page_orig,
  ^
In file included from <command-line>:0:0:
././include/linux/compiler_types.h:214:24: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
 #define asm_inline asm __inline
                        ^
./arch/x86/include/asm/alternative.h:256:2: note: in expansion of macro 'asm_inline'
  asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
  ^
./arch/x86/include/asm/page_64.h:49:2: note: in expansion of macro 'alternative_call_2'
  alternative_call_2(clear_page_orig,
  ^
./arch/x86/include/asm/segment.h: In function 'vdso_read_cpunode':
././include/linux/compiler_types.h:214:24: error: expected '(' before '__inline'
 #define asm_inline asm __inline
                        ^
./arch/x86/include/asm/alternative.h:240:2: note: in expansion of macro 'asm_inline'
  asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
  ^
./arch/x86/include/asm/segment.h:266:2: note: in expansion of macro 'alternative_io'
  alternative_io ("lsl %[seg],%[p]",
  ^
In file included from ./arch/x86/include/asm/barrier.h:5:0,
                 from ./include/linux/compiler.h:323,
                 from ./include/linux/export.h:42,
                 from ./include/linux/linkage.h:7,
                 from ./include/linux/kernel.h:8,
                 from ./include/linux/list.h:9,
                 from ./include/linux/module.h:9,
                 from /usr/src/ipt-netflow/cc-test-build/test.c:1:
./arch/x86/include/asm/alternative.h:108:2: error: expected identifier or '(' before string constant
  "# ALT: oldnstr\n"      \
  ^
./arch/x86/include/asm/alternative.h:159:2: note: in expansion of macro 'OLDINSTR'
  OLDINSTR(oldinstr, 1)      \
  ^
./arch/x86/include/asm/alternative.h:240:23: note: in expansion of macro 'ALTERNATIVE'
  asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
                       ^
./arch/x86/include/asm/segment.h:266:2: note: in expansion of macro 'alternative_io'
  alternative_io ("lsl %[seg],%[p]",
  ^
In file included from <command-line>:0:0:
././include/linux/compiler_types.h:214:24: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
 #define asm_inline asm __inline
                        ^
./arch/x86/include/asm/alternative.h:240:2: note: in expansion of macro 'asm_inline'
  asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
  ^
./arch/x86/include/asm/segment.h:266:2: note: in expansion of macro 'alternative_io'
  alternative_io ("lsl %[seg],%[p]",
  ^
./arch/x86/include/asm/special_insns.h: In function 'clflushopt':
././include/linux/compiler_types.h:214:24: error: expected '(' before '__inline'
 #define asm_inline asm __inline
                        ^
./arch/x86/include/asm/alternative.h:240:2: note: in expansion of macro 'asm_inline'
  asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
  ^
./arch/x86/include/asm/special_insns.h:207:2: note: in expansion of macro 'alternative_io'
  alternative_io(".byte " __stringify(NOP_DS_PREFIX) "; clflush %P0",
  ^
In file included from ./arch/x86/include/asm/barrier.h:5:0,
                 from ./include/linux/compiler.h:323,
                 from ./include/linux/export.h:42,
                 from ./include/linux/linkage.h:7,
                 from ./include/linux/kernel.h:8,
                 from ./include/linux/list.h:9,
                 from ./include/linux/module.h:9,
                 from /usr/src/ipt-netflow/cc-test-build/test.c:1:
./arch/x86/include/asm/alternative.h:108:2: error: expected identifier or '(' before string constant
  "# ALT: oldnstr\n"      \
  ^

If you need more output I can attach all.

[gavrilov-i]

Hi all, I've found the reason of the specified issue:
modern kernels requires newer GCC version than standard one (4.8.5).
installing GCC 9 fixed the build:

yum --enablerepo=extras install centos-release-scl-rh
yum install devtoolset-9-gcc
scl enable devtoolset-9 bash

Hope this will help others.

[aabc]

Thanks for the report and solution!