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Message-ID: <20210120124055.GG20820@kadam>
Date: Wed, 20 Jan 2021 15:40:55 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: Ilya Dryomov <idryomov@...il.com>
Cc: kbuild@...ts.01.org, kbuild test robot <lkp@...el.com>,
kbuild-all@...ts.01.org, LKML <linux-kernel@...r.kernel.org>,
Ceph Development <ceph-devel@...r.kernel.org>
Subject: Re: [kbuild] net/ceph/messenger_v1.c:1099:23: warning: Boolean
result is used in bitwise operation. Clarify expression with parentheses.
On Wed, Jan 20, 2021 at 12:01:59PM +0100, Ilya Dryomov wrote:
> On Tue, Jan 19, 2021 at 8:46 PM Dan Carpenter <dan.carpenter@...cle.com> wrote:
> >
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head: 1e2a199f6ccdc15cf111d68d212e2fd4ce65682e
> > commit: 2f713615ddd9d805b6c5e79c52e0e11af99d2bf1 libceph: move msgr1 protocol implementation to its own file
> > compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@...el.com>
> >
> >
> > cppcheck possible warnings: (new ones prefixed by >>, may not real problems)
> >
> > >> net/ceph/messenger_v1.c:1099:23: warning: Boolean result is used in bitwise operation. Clarify expression with parentheses. [clarifyCondition]
> > BUG_ON(!con->in_msg ^ skip);
> > ^
> >
> > vim +1099 net/ceph/messenger_v1.c
> >
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1033 static int read_partial_message(struct ceph_connection *con)
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1034 {
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1035 struct ceph_msg *m = con->in_msg;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1036 int size;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1037 int end;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1038 int ret;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1039 unsigned int front_len, middle_len, data_len;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1040 bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1041 bool need_sign = (con->peer_features & CEPH_FEATURE_MSG_AUTH);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1042 u64 seq;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1043 u32 crc;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1044
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1045 dout("read_partial_message con %p msg %p\n", con, m);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1046
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1047 /* header */
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1048 size = sizeof (con->in_hdr);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1049 end = size;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1050 ret = read_partial(con, end, size, &con->in_hdr);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1051 if (ret <= 0)
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1052 return ret;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1053
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1054 crc = crc32c(0, &con->in_hdr, offsetof(struct ceph_msg_header, crc));
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1055 if (cpu_to_le32(crc) != con->in_hdr.crc) {
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1056 pr_err("read_partial_message bad hdr crc %u != expected %u\n",
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1057 crc, con->in_hdr.crc);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1058 return -EBADMSG;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1059 }
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1060
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1061 front_len = le32_to_cpu(con->in_hdr.front_len);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1062 if (front_len > CEPH_MSG_MAX_FRONT_LEN)
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1063 return -EIO;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1064 middle_len = le32_to_cpu(con->in_hdr.middle_len);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1065 if (middle_len > CEPH_MSG_MAX_MIDDLE_LEN)
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1066 return -EIO;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1067 data_len = le32_to_cpu(con->in_hdr.data_len);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1068 if (data_len > CEPH_MSG_MAX_DATA_LEN)
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1069 return -EIO;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1070
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1071 /* verify seq# */
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1072 seq = le64_to_cpu(con->in_hdr.seq);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1073 if ((s64)seq - (s64)con->in_seq < 1) {
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1074 pr_info("skipping %s%lld %s seq %lld expected %lld\n",
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1075 ENTITY_NAME(con->peer_name),
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1076 ceph_pr_addr(&con->peer_addr),
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1077 seq, con->in_seq + 1);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1078 con->in_base_pos = -front_len - middle_len - data_len -
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1079 sizeof_footer(con);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1080 con->in_tag = CEPH_MSGR_TAG_READY;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1081 return 1;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1082 } else if ((s64)seq - (s64)con->in_seq > 1) {
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1083 pr_err("read_partial_message bad seq %lld expected %lld\n",
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1084 seq, con->in_seq + 1);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1085 con->error_msg = "bad message sequence # for incoming message";
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1086 return -EBADE;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1087 }
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1088
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1089 /* allocate message? */
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1090 if (!con->in_msg) {
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1091 int skip = 0;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1092
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1093 dout("got hdr type %d front %d data %d\n", con->in_hdr.type,
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1094 front_len, data_len);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1095 ret = ceph_con_in_msg_alloc(con, &con->in_hdr, &skip);
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1096 if (ret < 0)
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1097 return ret;
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 1098
> > 2f713615ddd9d805 Ilya Dryomov 2020-11-12 @1099 BUG_ON(!con->in_msg ^ skip);
> >
> > ! has higher precedence than ^. It's not clear that was intended
> > necessarily.
>
> Hi Dan,
>
> This line and the surrounding code date back to 2013, commit
> 2f713615ddd9 just moved it. It is correct (we either get a message
> to work with or get instructed to skip, in the latter case con->in_msg
> is expected to be NULL), so I'm inclined to leave it as is.
You could silence the warning and make the code look more intentional
by writing it like this:
BUG_ON((!con->in_msg) ^ skip);
regards,
dan carpenter
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