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McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang Cc: rcu@vger.kernel.org Subject: [PATCH RFC v1 4/6] rcu: drop redundant defer_qs_pending clear in irqrestore handler Date: Fri, 22 May 2026 10:23:38 -0400 Message-Id: <20260522142342.1536533-5-joelagnelf@nvidia.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260522142342.1536533-1-joelagnelf@nvidia.com> References: <20260522142342.1536533-1-joelagnelf@nvidia.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: BL1PR13CA0285.namprd13.prod.outlook.com (2603:10b6:208:2bc::20) 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_|MN0PR12MB5786:EE_ X-MS-Office365-Filtering-Correlation-Id: 2b11e240-b558-4ac5-82a0-08deb80dc885 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|366016|921020|11063799006|22082099003|56012099003|18002099003; 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Remove it. Effect: PENDING now stays set from arming until the next per-CPU GP advance, future arming attempts on the same CPU within the same GP are gated by the rcu_read_unlock_special(). This serves both as an optimization (should not need new irq_work again this GP - for the compounded section case, we detect and clear it there), and reduces risks of recursion due to clearing too aggressively. Signed-off-by: Joel Fernandes --- kernel/rcu/tree_plugin.h | 2 -- 1 file changed, 2 deletions(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 2da009dbe64c..bb5f955a06df 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -487,8 +487,6 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) union rcu_special special; rdp = this_cpu_ptr(&rcu_data); - if (rdp->defer_qs_pending == DEFER_QS_PENDING) - rcu_defer_qs_clear(rdp); /* * If RCU core is waiting for this CPU to exit its critical section, -- 2.34.1