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McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Boqun Feng , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Davidlohr Bueso , Joel Fernandes , rcu@vger.kernel.org Subject: [PATCH v3 01/14] rcu: introduce rcu_defer_qs_clear() helper Date: Thu, 18 Jun 2026 14:50:17 -0400 Message-Id: <20260618185030.376450-2-joelagnelf@nvidia.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260618185030.376450-1-joelagnelf@nvidia.com> References: <20260618185030.376450-1-joelagnelf@nvidia.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: BL0PR05CA0001.namprd05.prod.outlook.com (2603:10b6:208:91::11) To DS0PR12MB6486.namprd12.prod.outlook.com (2603:10b6:8:c5::21) 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: DS0PR12MB6486:EE_|SJ2PR12MB9088:EE_ X-MS-Office365-Filtering-Correlation-Id: fab9b24d-c1c2-4bac-747f-08decd6a9110 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|366016|376014|23010399003|1800799024|56012099006|11063799006|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?3Mz+O0h/MoVQooCTWElI0SH7qXb0RhzM0TqdYeTkmweWVQ+bwUeqVbQqklwH?= =?us-ascii?Q?2ErsBFIgNOPniVu77AZoq7eqjx6bJ92wk9vwN6JXpySqa4lfh1xQFp5EJite?= =?us-ascii?Q?xYtAn2qviexKS5s0n74FTAzEhyAp50wsQiWxvSmnixkUW60xS1zzTsEBOnf8?= =?us-ascii?Q?zr8anNsUoDK2CzQLmeM1vS1dDuWfv6jHpl+WD/q15+8TzD6UDuzbyig5lX6j?= =?us-ascii?Q?8geTUjFL+T/mn/qIK98U2q5KR4Mu4pl+URbnFzJ4vxlPrHH0sxPSY+60fwET?= =?us-ascii?Q?OoEUBUesLHWJoFY9ZeE8rAfSaoMdgh3bjFbR+xxp6c2Y3wLM5S1nvC2OLiY7?= =?us-ascii?Q?UKUu0gOHb/KtosFPz8ZKhaD5TQoldrD6QthR+Zu53o7uRqaRvZOmEGinHyjo?= =?us-ascii?Q?jGPTUrK1vJ0/EmAFGh+2Fddf8LwafpyUjjyld9s/my4rBNvBibDi6XgYnYsi?= =?us-ascii?Q?mPPg+hml5gRRb4YAhK3S5u3BBfzaqAWYoezKcODhlpQyGmYwYed4w/1dDf1l?= =?us-ascii?Q?9VxUm9fhGBpB4ucfLvltJYybj8YwN/C0ZuFYQ/fre7pdMfd1nn5BEKUzR8Uc?= =?us-ascii?Q?V+TVKasjY0CjHM95xr5PtM9WguPSpFVzb6cKuvB70kioz6vML+lZZKkrQmYv?= =?us-ascii?Q?mX3j/qbbb0yVcrKQ42w80jymQtWHbGnrBPswzwQS5UQs24heJEfzVqLA1Gqa?= =?us-ascii?Q?kQLJgNiEwcgn9ITZL8G6gHB/3g1ctyXDA+V0cxAIzMILnoBOt+ou+KZ+DVSo?= =?us-ascii?Q?o1Jugy9uuLecttocSS621fLOgt56OQicr4Y/oZpb9eZ59rBp28lFg7tNy/ZQ?= =?us-ascii?Q?TJyfR/xA/2+Z3v6tP+iV8mN2Q7aOA7Pz62JG3W3acHTKjtWcsTRqLsHls1OZ?= =?us-ascii?Q?3qeGeiTtdyvvsr9OuJH4EU0BkBSVZVDTqkm5+/6dKYP0BlXyzJ2wQve6Mw2t?= =?us-ascii?Q?00c/YsAu30Xwo5z26ycuhIomaX19pEtdrfzMVufmasFc8pBJEeVTCBxQmebB?= =?us-ascii?Q?16dAW3+gmpdNl81dp5hb1ZPHgp7BBa5gEOKkYCVftIbp6v2TNm0JqJtCi+1a?= =?us-ascii?Q?cw6HRPA2DKm+m70GQZacm3qy6AwJ8y4JjJ0OfRFz7mPFRdgfh1cWQXjhc012?= =?us-ascii?Q?wHFA06MCVa8sqh3yg1BpewH1VCFnLS80Z4FYkewJPLUtkxDgomuk7SdDBooA?= =?us-ascii?Q?RkJM51vdqyxSQBpSkIaWWfM28Q55A516rywz8pbFl6mLSBbwlCmg1xzG9QlW?= =?us-ascii?Q?kP7jFYLcAWhA3Ng0IaWG5oPPO9C4WxekM+dVAVTJOfO53mhRPQ6j2vvWmQ3I?= =?us-ascii?Q?GGCLQsvA2oIcI+TostQ80si4355vIT3XU1BTSj+VE1tsDlvLALTxfDfUuhW6?= =?us-ascii?Q?QvnJLSUSMoR3hdkksXILjEvtabuvwOF33VZEJCz+VxYLXSWR7HUoPrDqAuMZ?= =?us-ascii?Q?s5hh/LYFW8sH2lX1ItqEq86MpkSUStyzN0upzmOWiTJD+unNDG0oWx89a+Zt?= =?us-ascii?Q?ZNheICG4DEIP/dvM708TA41AbqeoOjtcxxcJmQhccYy6WIu0KBwcWwtlxN1g?= =?us-ascii?Q?qMHvXXkejqyApLHm3FincjKL7ddEBGD4cl54hA/cQdL2WXWUi/kWuWcF7iUH?= =?us-ascii?Q?UOA3E9sswMzvAsZ6fznIkkHUthinGKt/IQsHvdwMsknSlyuYMBjnmPD0MdOw?= =?us-ascii?Q?78iB/NznTGeG7XsG0VF116Rx2ttMXGVa84+uvADV/d4F8yRz8Op82PmPAN0s?= =?us-ascii?Q?mzQB76aO9A=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: fab9b24d-c1c2-4bac-747f-08decd6a9110 X-MS-Exchange-CrossTenant-AuthSource: DS0PR12MB6486.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jun 2026 18:51:11.9768 (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: g8v655wLrMfo4ueu6Hdb5Ahpt+M29k4VWBv2SaK56wptyvL5nkWbTmxqb8YeYJospFRA1OLzSKKkHuawA0R9Qw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB9088 Currently rdp->defer_qs_pending transitions from DEFER_QS_PENDING to DEFER_QS_IDLE at two sites: rcu_preempt_deferred_qs_irqrestore() and rcu_preempt_deferred_qs_handler() (depth>0 reset). Both write the IDLE value directly. Introduce a single inline helper rcu_defer_qs_clear() in tree.h and route both sites through it. This becomes the single PENDING->IDLE transition point for upcoming work. Signed-off-by: Joel Fernandes --- kernel/rcu/tree.h | 5 +++++ kernel/rcu/tree_plugin.h | 4 ++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 7dfc57e9adb1..4069132f9d44 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -296,6 +296,11 @@ struct rcu_data { int cpu; }; +static inline void rcu_defer_qs_clear(struct rcu_data *rdp) +{ + WRITE_ONCE(rdp->defer_qs_pending, DEFER_QS_IDLE); +} + /* Values for nocb_defer_wakeup field in struct rcu_data. */ #define RCU_NOCB_WAKE_NOT 0 #define RCU_NOCB_WAKE_BYPASS 1 diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 95ad967adcf3..8637f405cb47 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -488,7 +488,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) rdp = this_cpu_ptr(&rcu_data); if (rdp->defer_qs_pending == DEFER_QS_PENDING) - rdp->defer_qs_pending = DEFER_QS_IDLE; + rcu_defer_qs_clear(rdp); /* * If RCU core is waiting for this CPU to exit its critical section, @@ -645,7 +645,7 @@ static void rcu_preempt_deferred_qs_handler(struct irq_work *iwp) * 5. Deferred QS reporting does not happen. */ if (rcu_preempt_depth() > 0) - WRITE_ONCE(rdp->defer_qs_pending, DEFER_QS_IDLE); + rcu_defer_qs_clear(rdp); } /* -- 2.34.1