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Tue, 26 May 2026 17:41:11 -0700 Date: Tue, 26 May 2026 17:41:09 -0700 From: Nicolin Chen To: Qinxin Xia CC: , , , , , , , , , , , Subject: Re: [PATCH 1/5] iommu/arm-smmu-v3: Add basic debugfs framework Message-ID: References: <20260328101706.3448655-1-xiaqinxin@huawei.com> <20260520063714.2440584-1-xiaqinxin@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260520063714.2440584-1-xiaqinxin@huawei.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA2PEPF00003AE4:EE_|PH7PR12MB7937:EE_ X-MS-Office365-Filtering-Correlation-Id: 571548e1-4457-4482-1ae8-08debb88acd4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|7416014|376014|36860700016|4143699003|11063799006|56012099006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.233;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge2.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(7416014)(376014)(36860700016)(4143699003)(11063799006)(56012099006)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: QXCZ1VCkK+p1ogyHszqxL8y+fK5tUtn6Pr4SFTcRYR0bi1rN6/4tU2r5/MXqWBJyXPIFIUFOxL2XsIh7YpnbCLPUI9wAXPlTxqcZJzm5+tEiYOr6rnnMfhsNNa5UqLDI93MlKk/1OAqOg35XuT+pZ5DD6URquzZKvOxaH8bN3ls0RvipTuHFRVDKemQxRTuUVQ6O35jnlGLulPFP5cKxTS1aLTHl/MpYt0fAJB6X/Nf59iBUtUhAo/8uMIBQtV2YYyqCZhMhFP2GsaEpkdf8i7o1dRq98bLOeE0KVzQSlk95BQlVgvbkBSrpyB6y62Y+PTJ8tWlNlVf2qzFqMCw8T8U/ceZavtFfIwjqRHtmiRqlpQUzgSpOGQvrC5TdQUM+dD5yIjtwphUYK2CKAwBOlwksDEOobuBlbzmnDxRvr59KrWwSajARISn68a9fZeGj X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 May 2026 00:41:22.1778 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 571548e1-4457-4482-1ae8-08debb88acd4 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.233];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SA2PEPF00003AE4.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7937 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260526_174132_763317_146C17DC X-CRM114-Status: GOOD ( 16.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 20, 2026 at 02:37:07PM +0800, Qinxin Xia wrote: > +/** > + * arm_smmu_debugfs_setup() - Initialize debugfs for SMMU device > + * @smmu: SMMU device to setup debugfs for > + * @name: SMMU device name Nit: "device name" sounds like dev_name(); maybe sysfs node name? > + * This function creates the basic debugfs directory structure for an SMMU device. > + * > + * Return: 0 on success, negative error code on failure Usually, a debugfs_setup function uses void as a no-fail function. So, perhaps it should do the same? The caller only spits a warning print, which could be a part of revert path of this function if it is really necessary. > + */ > +int arm_smmu_debugfs_setup(struct arm_smmu_device *smmu, const char *name) > +{ > + struct arm_smmu_debugfs *debugfs; > + struct dentry *smmu_dir; > + > + /* Create root directory if it doesn't exist */ > + scoped_guard(mutex, &arm_smmu_debugfs_lock) { > + if (!smmu_debugfs_root) { > + /* Once created, it will not be removed */ > + smmu_debugfs_root = debugfs_create_dir("arm_smmu_v3", > + iommu_debugfs_dir); > + if (IS_ERR(smmu_debugfs_root)) { > + smmu_debugfs_root = NULL; > + return -ENOMEM; > + } > + } > + } > + > + /* Allocate debugfs structure */ > + debugfs = kzalloc_obj(*debugfs); > + if (!debugfs) > + return -ENOMEM; > + > + /* Create SMMU instance directory */ > + smmu_dir = debugfs_create_dir(name, smmu_debugfs_root); > + if (IS_ERR(smmu_dir)) { > + kfree(debugfs); > + smmu->debugfs = NULL; smmu->debugfs is NULL already since it's unset yet. > +void arm_smmu_debugfs_remove(struct arm_smmu_device *smmu) > +{ > + struct arm_smmu_debugfs *debugfs; > + struct dentry *smmu_dir; > + > + scoped_guard(mutex, &arm_smmu_debugfs_lock) { > + debugfs = smmu->debugfs; Isn't the lock used to fence smmu_debugfs_root? smmu->debugfs is per-smmu and freed per-smmu. Where is the race? Nicolin