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Thu, 16 Apr 2026 16:29:02 -0700 From: Nicolin Chen To: Will Deacon , Robin Murphy , "Joerg Roedel" , Bjorn Helgaas , "Jason Gunthorpe" CC: "Rafael J . Wysocki" , Len Brown , Pranjal Shrivastava , Mostafa Saleh , Lu Baolu , Kevin Tian , , , , , , , Shuai Xue Subject: [PATCH v3 05/11] iommu: Change group->devices to RCU-protected list Date: Thu, 16 Apr 2026 16:28:34 -0700 Message-ID: <12a224061de4fff9e0725909fd0ba4e14996ff08.1776381841.git.nicolinc@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PEPF00002315:EE_|CH3PR12MB9217:EE_ X-MS-Office365-Filtering-Correlation-Id: b9d50827-81c4-45b4-9464-08de9c10012a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|36860700016|82310400026|1800799024|18002099003|56012099003|22082099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(7416014)(376014)(36860700016)(82310400026)(1800799024)(18002099003)(56012099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: R+a7cUsTqsfN5ONYdFhoWchu2GHPlEpIqSX8M8EZCF27MxhuJYPVM7lpdv2m32CgAY0NHbOjZQPtpneiXVPvtPORpD3gJe3nBl6SRB4hQrHSQHdVKcrZK2HBM8VOqJ5hRnR/d5MMxry4LQ9a36fFIQ9E0D1ShLNkMrB7jYfEA5P+NDFbQ+bK19jOL/9dX7FuphzKSbT9VwVdJD3B1TriVOvQRQHLRkSP1eTdyPuzyZd5Rf4l92iHGrFevWzQpBwbFQFFfnIF5OQNuSs0iTpSo3lrtJpfrqJ8s4T67ePm9HFY6mcuejcfzESV6afRl9rJ1okRM/gS2sR2cE5XIDuEB8teqi75f3Ink3VesGJ4Rd/AmHZyBlXM8kNOUAP6meg+D7agk8upkIuTDz9ijlib73/GP087NEVFIqoD/W/MaVMSsaoC3BrMptYmiuX8yadj X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Apr 2026 23:29:28.4851 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b9d50827-81c4-45b4-9464-08de9c10012a X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00002315.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9217 To allow lockless iterations of the group->devices list in an ISR context that cannot hold the group->mutex, change the list to be RCU protected. Signed-off-by: Nicolin Chen --- drivers/iommu/iommu.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 768ac728b4cc3..d1be62a07904a 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -84,18 +84,20 @@ struct group_device { */ bool blocked; unsigned int reset_depth; + struct rcu_head rcu; }; /* Iterate over each struct group_device in a struct iommu_group */ #define for_each_group_device(group, pos) \ - list_for_each_entry(pos, &(group)->devices, list) + list_for_each_entry_rcu(pos, &(group)->devices, list, \ + lockdep_is_held(&(group)->mutex)) static struct group_device *__dev_to_gdev(struct device *dev) { struct iommu_group *group = dev->iommu_group; struct group_device *gdev; - lockdep_assert_held(&group->mutex); + lockdep_assert(lockdep_is_held(&group->mutex) || rcu_read_lock_held()); for_each_group_device(group, gdev) { if (gdev->dev == dev) @@ -666,7 +668,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list * The gdev must be in the list before calling * iommu_setup_default_domain() */ - list_add_tail(&gdev->list, &group->devices); + list_add_tail_rcu(&gdev->list, &group->devices); WARN_ON(group->default_domain && !group->domain); if (group->default_domain) iommu_create_device_direct_mappings(group->default_domain, dev); @@ -697,7 +699,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list return 0; err_remove_gdev: - list_del(&gdev->list); + list_del_rcu(&gdev->list); __iommu_group_free_device(group, gdev); err_put_group: iommu_deinit_device(dev); @@ -745,7 +747,7 @@ static void __iommu_group_free_device(struct iommu_group *group, group->domain != group->default_domain); kfree(grp_dev->name); - kfree(grp_dev); + kfree_rcu(grp_dev, rcu); } /* Remove the iommu_group from the struct device. */ @@ -759,7 +761,7 @@ static void __iommu_group_remove_device(struct device *dev) if (device->dev != dev) continue; - list_del(&device->list); + list_del_rcu(&device->list); __iommu_group_free_device(group, device); if (dev_has_iommu(dev)) iommu_deinit_device(dev); @@ -1335,7 +1337,7 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) dev->iommu_group = group; mutex_lock(&group->mutex); - list_add_tail(&gdev->list, &group->devices); + list_add_tail_rcu(&gdev->list, &group->devices); mutex_unlock(&group->mutex); return 0; } -- 2.43.0