We created a new enum to allow different TCP state names between the kernel and
BPF sock_ops programs. Since we want to catch changes in the original enum, we
are comparing the values of the last entries of the enum types (which is
triggering the warning).
On 1/1/18, 8:02 PM, "kbuild test robot" <l...@intel.com> wrote:
Hi Lawrence,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on net-next/master]
[also build test WARNING on next-20171222]
[cannot apply to bpf-next/master linus/master net/master v4.15-rc6]
[if your patch is applied to the wrong git tree, please drop us a note to
help improve the system]
url:
https://github.com/0day-ci/linux/commits/Lawrence-Brakmo/bpf-More-sock_ops-callbacks/20180102-111550
config: x86_64-randconfig-x007-201800 (attached as .config)
compiler: gcc-7 (Debian 7.2.0-12) 7.2.1 20171025
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All warnings (new ones prefixed by >>):
In file included from arch/x86/include/asm/atomic.h:5:0,
from include/linux/atomic.h:5,
from include/linux/crypto.h:20,
from include/crypto/hash.h:16,
from net//ipv4/tcp.c:250:
net//ipv4/tcp.c: In function 'tcp_set_state':
>> net//ipv4/tcp.c:2041:34: warning: comparison between 'enum <anonymous>'
and 'enum <anonymous>' [-Wenum-compare]
BUILD_BUG_ON(BPF_TCP_MAX_STATES != TCP_MAX_STATES);
^
include/linux/compiler.h:301:19: note: in definition of macro
'__compiletime_assert'
bool __cond = !(condition); \
^~~~~~~~~
include/linux/compiler.h:324:2: note: in expansion of macro
'_compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:47:37: note: in expansion of macro
'compiletime_assert'
#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
^~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:71:2: note: in expansion of macro
'BUILD_BUG_ON_MSG'
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
^~~~~~~~~~~~~~~~
>> net//ipv4/tcp.c:2041:2: note: in expansion of macro 'BUILD_BUG_ON'
BUILD_BUG_ON(BPF_TCP_MAX_STATES != TCP_MAX_STATES);
^~~~~~~~~~~~
vim +/BUILD_BUG_ON +2041 net//ipv4/tcp.c
2036
2037 void tcp_set_state(struct sock *sk, int state)
2038 {
2039 int oldstate = sk->sk_state;
2040
> 2041 BUILD_BUG_ON(BPF_TCP_MAX_STATES != TCP_MAX_STATES);
2042 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk),
BPF_SOCK_OPS_STATE_CB_FLAG))
2043 tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_STATE_CB,
oldstate, state);
2044
2045 switch (state) {
2046 case TCP_ESTABLISHED:
2047 if (oldstate != TCP_ESTABLISHED)
2048 TCP_INC_STATS(sock_net(sk),
TCP_MIB_CURRESTAB);
2049 break;
2050
2051 case TCP_CLOSE:
2052 if (oldstate == TCP_CLOSE_WAIT || oldstate ==
TCP_ESTABLISHED)
2053 TCP_INC_STATS(sock_net(sk),
TCP_MIB_ESTABRESETS);
2054
2055 sk->sk_prot->unhash(sk);
2056 if (inet_csk(sk)->icsk_bind_hash &&
2057 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
2058 inet_put_port(sk);
2059 /* fall through */
2060 default:
2061 if (oldstate == TCP_ESTABLISHED)
2062 TCP_DEC_STATS(sock_net(sk),
TCP_MIB_CURRESTAB);
2063 }
2064
2065 /* Change state AFTER socket is unhashed to avoid closed
2066 * socket sitting in hash tables.
2067 */
2068 inet_sk_state_store(sk, state);
2069
---
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