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charset=UTF-8 Date: Wed, 07 Oct 2026 21:12:01 +0900 Message-Id: Cc: "Thorsten Blum" , "Alice Ryhl" , "David Airlie" , "Simona Vetter" , "Gary Guo" , "Timur Tabi" , "Robin Murphy" , "Tim Kovalenko" , , , Subject: Re: [PATCH] gpu: nova-core: firmware: fwsec: use zeroed() to zero-pad buffers From: "Alexandre Courbot" To: "Danilo Krummrich" References: <20261006100442.80432-3-blum@kernel.org> In-Reply-To: X-ClientProxiedBy: TYCP286CA0006.JPNP286.PROD.OUTLOOK.COM (2603:1096:400:26c::14) To MW4PR12MB6873.namprd12.prod.outlook.com (2603:10b6:303:20c::17) 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: MW4PR12MB6873:EE_|CHAPR12MB999248:EE_ X-MS-Office365-Filtering-Correlation-Id: e6eba444-b6ce-4a75-432d-08df246c32fb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|10070799003|7416014|23010399003|376014|56012099006|4143699003|11063799006|22082099003|10067099003|18002099003|6133799003; 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>>>> - ucode.extend_from_slice(code, GFP_KERNEL)?; >>>> - ucode.resize(aligned_code_size, 0, GFP_KERNEL)?; >>>> - >>>> + let mut ucode =3D KVec::zeroed(aligned_code_size, GFP_KER= NEL)?; >>>> + ucode[..code.len()].copy_from_slice(code); >>> >>> I kinda dislike that this is now a potential panic, but it does better = express >>> the intent. >> >> IMHO the original code expresses the intent just as well, and avoids >> writing the area covered by `code` twice, on top of not introducing a >> potential panic site. > > I'm referring to the fact that the original code expresses "I may allocat= e" > three times, while the intent is that the allocation is exactly > aligned_code_size. > > This is much more clear with the new code, if we really want to avoid a > potential panic here, we could use get_mut(), but the ergonomics isn't gr= eat. > > That said, I wouldn't mind adding something like Vec::extend_within_capac= ity(), > which fails if there's not enough capacity. You know how I feel about panic sites in the code, even if they appear to be untaken today. :) Another thing we could do is replace `KVec::with_capacity` with `KVec::new`, removing one potential allocation site. The added padding (which in practice is likely to be 0-sized per the comment in the code) is unlikely to trigger a resize anyway.