Re: [PATCH 2/4] ipv6: mld: rename mldv2_mrc() and add mldv2_qqi()

kernel test robot
2026-03-27T15:49:47Z

Hi Ujjal,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]
[also build test WARNING on net/main klassert-ipsec/master linus/master v7.0-rc5 next-20260326]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Ujjal-Roy/ipv4-igmp-get-rid-of-IGMPV3_-QQIC-MRC-and-simplify-calculation/20260327-083159
base: net-next/main
patch link: https://lore.kernel.org/r/20260326150742.50289-3-royujjal%40gmail.com
patch subject: [PATCH 2/4] ipv6: mld: rename mldv2_mrc() and add mldv2_qqi()
config: x86_64-randconfig-121-20260327 (https://download.01.org/0day-ci/archive/20260327/202603272318.WLQHm8jS-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260327/202603272318.WLQHm8jS-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603272318.WLQHm8jS-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
net/ipv6/mcast.c: note: in included file:
include/net/mld.h:32:43: sparse: sparse: array of flexible structures
>> include/net/mld.h:147:30: sparse: sparse: cast to restricted __be16

vim +147 include/net/mld.h

29
30 struct mld2_report {
31 struct icmp6hdr mld2r_hdr;
> 32 struct mld2_grec mld2r_grec[];
33 };
34
35 #define mld2r_type mld2r_hdr.icmp6_type
36 #define mld2r_resv1 mld2r_hdr.icmp6_code
37 #define mld2r_cksum mld2r_hdr.icmp6_cksum
38 #define mld2r_resv2 mld2r_hdr.icmp6_dataun.un_data16[0]
39 #define mld2r_ngrec mld2r_hdr.icmp6_dataun.un_data16[1]
40
41 /* MLDv2 Query */
42 struct mld2_query {
43 struct icmp6hdr mld2q_hdr;
44 struct in6_addr mld2q_mca;
45 #if defined(__LITTLE_ENDIAN_BITFIELD)
46 __u8 mld2q_qrv:3,
47 mld2q_suppress:1,
48 mld2q_resv2:4;
49 #elif defined(__BIG_ENDIAN_BITFIELD)
50 __u8 mld2q_resv2:4,
51 mld2q_suppress:1,
52 mld2q_qrv:3;
53 #else
54 #error "Please fix <asm/byteorder.h>"
55 #endif
56 __u8 mld2q_qqic;
57 __be16 mld2q_nsrcs;
58 struct in6_addr mld2q_srcs[];
59 };
60
61 #define mld2q_type mld2q_hdr.icmp6_type
62 #define mld2q_code mld2q_hdr.icmp6_code
63 #define mld2q_cksum mld2q_hdr.icmp6_cksum
64 #define mld2q_mrc mld2q_hdr.icmp6_maxdelay
65 #define mld2q_resv1 mld2q_hdr.icmp6_dataun.un_data16[1]
66
67 /* RFC3810, 5.1.3. Maximum Response Code:
68 *
69 * If Maximum Response Code >= 32768, Maximum Response Code represents a
70 * floating-point value as follows:
71 *
72 * 0 1 2 3 4 5 6 7 8 9 A B C D E F
73 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
74 * |1| exp | mant |
75 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
76 */
77 #define MLDV2_MRC_EXP(value) (((value) >> 12) & 0x0007)
78 #define MLDV2_MRC_MAN(value) ((value) & 0x0fff)
79
80 /* RFC3810, 5.1.9. QQIC (Querier's Query Interval Code):
81 *
82 * If QQIC >= 128, QQIC represents a floating-point value as follows:
83 *
84 * 0 1 2 3 4 5 6 7
85 * +-+-+-+-+-+-+-+-+
86 * |1| exp | mant |
87 * +-+-+-+-+-+-+-+-+
88 */
89 #define MLDV2_QQIC_EXP(value) (((value) >> 4) & 0x07)
90 #define MLDV2_QQIC_MAN(value) ((value) & 0x0f)
91
92 #define MLD_QQIC_MIN_THRESHOLD 128
93 #define MLD_MRC_MIN_THRESHOLD 32768UL
94 #define MLDV1_MRD_MAX_COMPAT (MLD_MRC_MIN_THRESHOLD - 1)
95
96 #define MLD_MAX_QUEUE 8
97 #define MLD_MAX_SKBS 32
98
99 /* V2 exponential field decoding */
100
101 /* Calculate Maximum Response Delay from Maximum Response Code
102 *
103 * RFC3810, 5.1.3. defines the decoding formula:
104 * 0 1 2 3 4 5 6 7 8 9 A B C D E F
105 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
106 * |1| exp | mant |
107 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
108 * Maximum Response Delay = (mant | 0x1000) << (exp+3)
109 */
110 static inline unsigned long mldv2_mrd(const struct mld2_query *mlh2)
111 {
112 /* RFC3810, relevant sections:
113 * - 5.1.3. Maximum Response Code
114 * - 9.3. Query Response Interval
115 */
116 unsigned long mc_mrc = ntohs(mlh2->mld2q_mrc);
117
118 if (mc_mrc < MLD_MRC_MIN_THRESHOLD) {
119 return mc_mrc;
120 } else {
121 unsigned long mc_man, mc_exp;
122
123 mc_exp = MLDV2_MRC_EXP(mc_mrc);
124 mc_man = MLDV2_MRC_MAN(mc_mrc);
125
126 return ((mc_man | 0x1000) << (mc_exp + 3));
127 }
128 }
129
130 /* Calculate Querier's Query Interval from Querier's Query Interval Code
131 *
132 * RFC3810, 5.1.9. defines the decoding formula:
133 * 0 1 2 3 4 5 6 7
134 * +-+-+-+-+-+-+-+-+
135 * |1| exp | mant |
136 * +-+-+-+-+-+-+-+-+
137 * QQI = (mant | 0x10) << (exp + 3)
138 */
139 static inline unsigned long mldv2_qqi(const struct mld2_query *mlh2)
140 {
141 /* RFC3810, relevant sections:
142 * - 5.1.9. QQIC (Querier's Query Interval Code)
143 * - 9.2. Query Interval
144 * - 9.12. Older Version Querier Present Timeout
145 * (the [Query Interval] in the last Query received)
146 */
> 147 unsigned long qqic = ntohs(mlh2->mld2q_qqic);
148
149 if (qqic < MLD_QQIC_MIN_THRESHOLD) {
150 return qqic;
151 } else {
152 unsigned long mc_man, mc_exp;
153
154 mc_exp = MLDV2_QQIC_EXP(qqic);
155 mc_man = MLDV2_QQIC_MAN(qqic);
156
157 return ((mc_man | 0x10) << (mc_exp + 3));
158 }
159 }
160

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