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Miller" , Eric Dumazet , Paolo Abeni , Andrew Lunn , Florian Fainelli Subject: Re: [RFC PATCH net-next] net: dsa: replace NETDEV_PRE_CHANGE_HWTSTAMP notifier with a stub Message-ID: References: <20230405165115.3744445-1-vladimir.oltean@nxp.com> <20230405203107.lsz53fbu257d3pmc@skbuf> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230405203107.lsz53fbu257d3pmc@skbuf> X-ClientProxiedBy: AM0PR06CA0106.eurprd06.prod.outlook.com (2603:10a6:208:fa::47) To PH0PR13MB4842.namprd13.prod.outlook.com (2603:10b6:510:78::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR13MB4842:EE_|DS7PR13MB4720:EE_ X-MS-Office365-Filtering-Correlation-Id: ec432c96-6d87-4ffb-ff29-08db366e4d64 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH0PR13MB4842.namprd13.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230028)(4636009)(376002)(346002)(136003)(396003)(39840400004)(366004)(451199021)(186003)(38100700002)(8936002)(6506007)(6512007)(8676002)(478600001)(6486002)(54906003)(316002)(66946007)(86362001)(66476007)(66556008)(4326008)(6916009)(6666004)(36756003)(41300700001)(44832011)(2906002)(2616005)(5660300002)(83380400001);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?CPc9dg84yMYCwctB64msnzS0nXY9/swkUCQSBRTpcV++e8109Bg51TprkibH?= =?us-ascii?Q?6JT1WvUEJyV4UlGwbuZQHHy/nmU8E0eU2rSNWd6sgJs7ceqADjr5RAAL2GQW?= =?us-ascii?Q?e4Iv/xL1qEWNDQxz3Nf9GmubptV+4ZDhoyapa686RwYUPrhgyI/F2K17W+Tz?= =?us-ascii?Q?vRrrmOZyBakGJVPDIhHfzDhe7Y5kXM52UvFETyn7OkVihShKy8G++4tIn51Q?= =?us-ascii?Q?MXKz21xHhD0wOdfY6h1pn4pevOjHhtn++eCNk3EwB2Be1w3aqBNEGUbZWuQd?= =?us-ascii?Q?0TWXcrQXj2vQe+//uz8JMIc9ZIAbBDraVGOK3q+asOwK/EgygDjMYvjhir5B?= =?us-ascii?Q?6AyZcvHaDBICr5bOXaMSl8jlvp0JvA0xZsMRT+pP6N3byQWcbs3lnQ414fU8?= =?us-ascii?Q?X6Y5eXhDEKF9ST3l2Y99jtilPyLgssytYtdVhU8OUtWNUR23iQ1SgrGmERsJ?= =?us-ascii?Q?CoDlqmN05D/tSQs1cTzti2G2fvU4jyKciCgdwqXqp9tPF7NtPZ/sef7SEz2n?= =?us-ascii?Q?g3W6H7RpqL6KexRh3o1rWUh2NujDe13TjmuoJKuDtF5P1qh9G+ikhGQ+HhZV?= =?us-ascii?Q?ih5VVX46xkBQL3To2Nmr7Ycp1lwJCJSw+Chi7gerksihf34v5q7ZmgNxkS0u?= =?us-ascii?Q?Uh4ztlp8iB0HX5sslF8m2W8Vr6DZs2cxjP5QyTQOBCFzWiqYKBETGBGcsj/r?= =?us-ascii?Q?WvTCDNgSdJCxNSL5WkiG6Gw6teJQM4yqAiaJCSTFyt9ZKsYiv2chHz4N/4Nc?= =?us-ascii?Q?gZuNGXKsizvw7FI3Ld5Qlb420e3+DYZUH7kFz/205i5EyCIGtqPd+GTry40t?= =?us-ascii?Q?HaIwCwSck5J5v1lK7qgTMNvHJInaN8zRr7iqIe1C9n+Lk64P+KKL4YuU76m+?= =?us-ascii?Q?f6hh9wxPKY3ErAGq4rQIcqaciOQ10lDc4N6MWuy1nltLoL1FRPAHi/fy6vIo?= =?us-ascii?Q?Gxl/fReNSJB11N44YS/xbLqk/1a0ZH64MOG6/fJ2wSG/5ZM9pDQ0An75Nthg?= =?us-ascii?Q?irjSVmZoFCQEmXSvWAXdSMtioZ4GVjvT515//o6G71eoYUcBsG+DR0IZSEYl?= =?us-ascii?Q?HCr9CMpKdmonFHmtTUWwMsMNPMI4fOS+6vf40PwBtonfnIUensvE/bQmtJTp?= =?us-ascii?Q?JNLch+rJED6KMBXuPIuUpZ33rCV2n4sJ5200ZvoqCMuhfCMljjn9E1QLHgmx?= =?us-ascii?Q?I6Kkn+4tI7Wb9kx13jX34mWFqAIfuA94mvhQkTWcansW7wm5M/7/2lljc/KG?= =?us-ascii?Q?2G0UG+JobnN/CGnLnknNvxLMzgxRPtzMJ5LK2+/o2Elhy8Q7sOWYgY01p2gq?= =?us-ascii?Q?cwmJweEfxeRAvf0CpRzPtcMJa44kR6uOSQQAchfyfpWKaQ9Dq5vgUoQt2Jy+?= =?us-ascii?Q?ZbyzLFmP/L5iswRc+k0Kq77uZEXE6RaM0vTwBIrWBp21p8ask/EMmcmkGrV4?= =?us-ascii?Q?oScOtl2WUFjtzIP6dYXTS9LtcJiSIGzD8nTyb7z/Pmx4t3bjEpQR01AXytgt?= =?us-ascii?Q?WbANZW6PEjBRIWV2nJLEi+q3EHgDAMiJZl1r13R+IiHZ6bLrPs1BCcqVf/39?= =?us-ascii?Q?IzTxMlQcc9qvvNsh9NiJnwfQSM7u+Qj8t9JF6uJmUC6F1L0YeOBoypBuwaTz?= =?us-ascii?Q?u8897ei128BTNRX9erZ/SDMhjB5GgRh5uH5Ifc2kgMGswxmCnbB8yg8EEZyL?= =?us-ascii?Q?RHS+JA=3D=3D?= X-OriginatorOrg: corigine.com X-MS-Exchange-CrossTenant-Network-Message-Id: ec432c96-6d87-4ffb-ff29-08db366e4d64 X-MS-Exchange-CrossTenant-AuthSource: PH0PR13MB4842.namprd13.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Apr 2023 07:12:37.7130 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: fe128f2c-073b-4c20-818e-7246a585940c X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: iQ2ciWdMGcZKsJnmyZs6ws2olVXqj4EuYE4wdXKKc79xMnD7G9bYcsgFVhbRy5BANzw94dkg0om3JkP+nVvgFKMbhgQjxiiXFobtqCqLNKQ= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR13MB4720 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Apr 05, 2023 at 11:31:07PM +0300, Vladimir Oltean wrote: > On Wed, Apr 05, 2023 at 10:05:15PM +0200, Simon Horman wrote: > > > +static inline int dsa_master_hwtstamp_validate(struct net_device *dev, > > > + const struct kernel_hwtstamp_config *config, > > > + struct netlink_ext_ack *extack) > > > +{ > > > + int err; > > > + > > > + if (!netdev_uses_dsa(dev)) > > > + return 0; > > > + > > > + mutex_lock(&dsa_stubs_lock); > > > + > > > + if (dsa_stubs) > > > + err = dsa_stubs->master_hwtstamp_validate(dev, config, extack); > > > + > > > + mutex_unlock(&dsa_stubs_lock); > > > > nit: clang-16 tells me that err is uninitialised here if dsa_stubs is false. > > In fact, clang-16 is saying something much smarter than that, because I > did test this code path and it did work reliably (not like an uninitialized > return value would). > > It's saying that when netdev_uses_dsa() returns true, the DSA module has > surely been loaded, so the stubs have surely been registered, so the > mutex_lock() and the check for the NULL quality of dsa_stubs are > completely redundant and can be removed. For the record, what it had to say, when used with W=1, was: In file included from net/dsa/dsa.c:20: ./include/net/dsa_stubs.h:33:6: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized] if (dsa_stubs) ^~~~~~~~~ ./include/net/dsa_stubs.h:38:9: note: uninitialized use occurs here return err; ^~~ ./include/net/dsa_stubs.h:33:2: note: remove the 'if' if its condition is always true if (dsa_stubs) ^~~~~~~~~~~~~~ ./include/net/dsa_stubs.h:26:9: note: initialize the variable 'err' to silence this warning int err; ^ = 0 1 error generated. -- In file included from net/dsa/stubs.c:7: ./include/net/dsa_stubs.h:33:6: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized] if (dsa_stubs) ^~~~~~~~~ ./include/net/dsa_stubs.h:38:9: note: uninitialized use occurs here return err; ^~~ ./include/net/dsa_stubs.h:33:2: note: remove the 'if' if its condition is always true if (dsa_stubs) ^~~~~~~~~~~~~~ ./include/net/dsa_stubs.h:26:9: note: initialize the variable 'err' to silence this warning int err; ^ = 0 1 error generated.