Fix skbtracer.c

[MatheMatrix]

add KBUILD_MODNAME
fix dropstack

[MatheMatrix]

without patch:

[root@dev1-4 skbtracer]# python skbtracer.py
In file included from /virtual/main.c:9:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/inet_sock.h:26:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sock.h:64:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/filter.h:25:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sch_generic.h:21:
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/flow_offload.h:314:4: error: use of undeclared identifier 'KBUILD_MODNAME'
                        NL_SET_ERR_MSG_MOD(extack, "Mixing HW stats types for actions is not supported");
                        ^
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/netlink.h:96:27: note: expanded from macro 'NL_SET_ERR_MSG_MOD'
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
                                 ^
In file included from /virtual/main.c:9:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/inet_sock.h:26:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sock.h:64:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/filter.h:25:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sch_generic.h:21:
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/flow_offload.h:314:4: error: expected ';' at end of declaration
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/netlink.h:96:42: note: expanded from macro 'NL_SET_ERR_MSG_MOD'
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
                                                ^
In file included from /virtual/main.c:9:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/inet_sock.h:26:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sock.h:64:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/filter.h:25:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sch_generic.h:21:
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/flow_offload.h:348:3: error: use of undeclared identifier 'KBUILD_MODNAME'
                NL_SET_ERR_MSG_MOD(extack, "Driver supports only default HW stats type \"any\"");
                ^
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/netlink.h:96:27: note: expanded from macro 'NL_SET_ERR_MSG_MOD'
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
                                 ^
In file included from /virtual/main.c:9:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/inet_sock.h:26:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sock.h:64:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/filter.h:25:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sch_generic.h:21:
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/flow_offload.h:348:3: error: expected ';' at end of declaration
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/netlink.h:96:42: note: expanded from macro 'NL_SET_ERR_MSG_MOD'
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
                                                ^
In file included from /virtual/main.c:9:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/inet_sock.h:26:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sock.h:64:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/filter.h:25:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sch_generic.h:21:
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/flow_offload.h:352:3: error: use of undeclared identifier 'KBUILD_MODNAME'
                NL_SET_ERR_MSG_MOD(extack, "Driver does not support selected HW stats type");
                ^
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/netlink.h:96:27: note: expanded from macro 'NL_SET_ERR_MSG_MOD'
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
                                 ^
In file included from /virtual/main.c:9:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/inet_sock.h:26:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sock.h:64:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/filter.h:25:
In file included from /lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/sch_generic.h:21:
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/net/flow_offload.h:352:3: error: expected ';' at end of declaration
/lib/modules/4.18.0-240.15.1.el7.x86_64/build/include/linux/netlink.h:96:42: note: expanded from macro 'NL_SET_ERR_MSG_MOD'
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
                                                ^
6 errors generated.
Traceback (most recent call last):
  File "skbtracer.py", line 295, in <module>
    b = BPF(text=bpf_text)
  File "/usr/lib/python2.7/site-packages/bcc/__init__.py", line 325, in __init__
    raise Exception("Failed to compile BPF text")
Exception: Failed to compile BPF text

with patch:

[root@dev1-4 skbtracer]# python skbtracer.py -c 1
time       NETWORK_NS   CPU    INTERFACE          DEST_MAC     IP_LEN PKT_INFO                                 TRACE_INFO
[17:42:35 ][4026531992] 0      nil                000000000000 216    T_ACK,PSH:10.0.31.77:22->172.21.0.120:54155 ffff9b36d81c9e40.0:ip_output