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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Nikolay Aleksandrov , David Ahern , Shuah Khan , Andy Roulin , Yong Wang , Petr Machata , Ujjal Roy , bridge@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH net-next v4 3/5] ipv4: igmp: encode multicast exponential fields Message-ID: <20260413084710.GC209364@shredder> References: <20260412111047.1326-1-royujjal@gmail.com> <20260412111047.1326-4-royujjal@gmail.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260412111047.1326-4-royujjal@gmail.com> X-ClientProxiedBy: TL0P290CA0002.ISRP290.PROD.OUTLOOK.COM (2603:1096:950:5::10) To SA3PR12MB7901.namprd12.prod.outlook.com (2603:10b6:806:306::12) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA3PR12MB7901:EE_|DS4PR12MB9772:EE_ X-MS-Office365-Filtering-Correlation-Id: 11e382d0-4183-48d1-4d42-08de993945e0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014|56012099003|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?y8V/enAmhwkpoHb0Svp4nlo1IG5Mwb3Y5HawKARPqMUH73n+D9s7LNckFtk9?= =?us-ascii?Q?ugjJoZAaWB40RIFYk3+JwGJQMXwPMr2gNhr/YW1nf3w7Lg488/3TkefETtJx?= =?us-ascii?Q?AbM+kN26xvaZVRujo5HbBGM6fQl2wkgSX/2kQ3yAe0AVJAgdh9PgG0GbGWk+?= =?us-ascii?Q?to/sGtNfqwSyvHoZgYQO3xNdxLG01QPJaNJrrwhth5ccLtWod3CdOUZ4IijM?= =?us-ascii?Q?AmOzJvsgEe7K9aLW/gMeX1Q24DtBCMHHRJKxeYR+OTL9SbnPMjn3nzzJQyX2?= =?us-ascii?Q?qcFGntMZ3J4T0PG5yVyzh/xTTOuDGwgx52fcDdqgvGf1hrQJCCaLfUqYx2YB?= =?us-ascii?Q?p12h2ix+VTe+0ARQ6W93xJGn1M7bc/7bSd1BErP2CgLHgP+sT2UYar9SqpZZ?= =?us-ascii?Q?6ca9AxqbqwKOh+eWGifkZo2CUa0XCkkKW+Vi7mTG+ahOESExsEgfxnvhQPvo?= =?us-ascii?Q?H4IppYA4gKZXnQMZTDZW7SknBSXh6WL14tGkyU/5bP5Hbn8p7hbIoZWv/1FM?= =?us-ascii?Q?kTt5s4FaR+8uwLIboINJdMfCbay+MgL/DDZ4KVdNOe7gTpRvgs4hCm+RZmle?= =?us-ascii?Q?eg5kwyX6IDaOU2RZaz1fshz70/Pw0cFsZgg3WOrTS5c1fQ72Ts/za7143O6a?= =?us-ascii?Q?DF0EcY4EI7ouiehU8mRlCi9huhjxhzf3J6DnxEFp2XZ3HRSh9PRkjfQRFZ6e?= =?us-ascii?Q?Thur91qAEkU2wb90D9xe9AxmmKcsrlRtyDSyoKFE3sSc1kkkMFMye36alzxU?= =?us-ascii?Q?d3VI8b9hEniP3YSP34Wl5/olOeOhbFDC3E1UMQhYlFgM/rGMMjoeUQvsP0Pm?= =?us-ascii?Q?IUKRROW75murWgfJCrSGW68WCAzjnPGPJw/20BEYd4a1DyTaF4+Dq6q8mGC4?= =?us-ascii?Q?UL+rTEYc9HR8GQpDwLQtuxSYbSbJAflQqwFQPEb/Gn085PmuKKOVX2eBDWcX?= =?us-ascii?Q?9FtnLDW2eV9PeBBb/pdsELve3R7N1BVseDi/FmgCCQBUcTReDgFVDlJybdgG?= =?us-ascii?Q?xSJjdAmsm6ZFmEIp0ssZ9Di7g3NHMOSUV2x0sOvMJlPdpJAp4PNKBkFs0kYE?= =?us-ascii?Q?T9lGtcS52fQgOZRj/Vkh8j2/NdXa53XrdcuPoB89Crge7mrtxVqqKuDntvqz?= =?us-ascii?Q?uU8nf1WRiyR+s98Vlz/vJh5SvKnazyHSq/xXQX6M0uxfWeBL8K/UlIBGkz4A?= =?us-ascii?Q?jAwn+uuNawOswwyJW1KfGUiE7RJAG95juvj2Oki2zoclZ+9HXJPttA9nA50R?= =?us-ascii?Q?Q3LXsgVBUMOEcUta3j+qNHPrB7odtAWT8ReDTkxidY2uMLH9JRdb93aBQdAR?= =?us-ascii?Q?gxUkAEQSdgmt/+CncZCAWkKIBNSXiSPHyCrgObt0Gwh7HD4j4+IQjtDDJS+s?= =?us-ascii?Q?Sql/F42nEJiOKAfBkYKow8pqOM3NdAKvmxyMnIY0CDBR+qAQvpPt4QNjO2bH?= =?us-ascii?Q?gQ39MT/+0up1QoU0aaA7AHBtxzvvn76y62enFA+hhv0DMupmqU8eD0t54Zag?= =?us-ascii?Q?6xtBQxuWN/DuTgbtnPhk3UWzqc6UpM3To/Ix/tu7KX03zdGRJP0TeHWMdw0V?= =?us-ascii?Q?XAhV0pXFau/CTrmvebEHUIvHyuRjfSAqHB7PgEaBxowDrNGYAtpvPLBKdqRb?= =?us-ascii?Q?G2TBkXTuxrb2fmie1ATFEjlem/Wvg5fk/QyHbf+HjhjYZZC8U19qbR82WNJo?= =?us-ascii?Q?jwhzh47mHJqEEKiNKwaMQMcENowB+KH5P1IRnDD/lcN/q14r?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 11e382d0-4183-48d1-4d42-08de993945e0 X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Apr 2026 08:47:19.8857 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 5HFiydVj2BSt5G3xH34UoVN4SbvqMNi6z1AkNuT+iK+Aak6nuc2FAFYkGFfKrUG3Au2jP+ri+zx1/w8vZblrBw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS4PR12MB9772 On Sun, Apr 12, 2026 at 11:10:45AM +0000, Ujjal Roy wrote: > In IGMP, MRC and QQIC fields are not correctly encoded > when generating query packets. Since the receiver of the > query interprets these fields using the IGMPv3 floating- > point decoding logic, any value that exceeds the linear > threshold is incorrectly parsed as an exponential value, > leading to an incorrect interval calculation. > > Encode and assign the corresponding protocol fields during > query generation. Introduce the logic to dynamically > calculate the exponent and mantissa using bit-scan (fls). > This ensures MRC and QQIC fields (8-bit) are properly > encoded when transmitting query packets with intervals > that exceed their respective linear threshold value of > 128 (for MRT/QQI). > > RFC3376: for both MRC and QQIC, values >= 128 represent > the same floating-point encoding as follows: > 0 1 2 3 4 5 6 7 > +-+-+-+-+-+-+-+-+ > |1| exp | mant | > +-+-+-+-+-+-+-+-+ > > Signed-off-by: Ujjal Roy Reviewed-by: Ido Schimmel