linux-kernel - [PATCH v2 11/28] module: Use RCU in __is_module_percpu

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Message-ID: <20241220174731.514432-12-bigeasy@linutronix.de>
Date: Fri, 20 Dec 2024 18:41:25 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-modules@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Daniel Gomez <da.gomez@...sung.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v2 11/28] module: Use RCU in __is_module_percpu_address().

The modules list can be accessed under RCU assumption.

Use RCU protection instead preempt_disable().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/module/main.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 71e73deed76c0..126f7f05dedf8 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -450,8 +450,7 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
 	struct module *mod;
 	unsigned int cpu;
 
-	preempt_disable();
-
+	guard(rcu)();
 	list_for_each_entry_rcu(mod, &modules, list) {
 		if (mod->state == MODULE_STATE_UNFORMED)
 			continue;
@@ -468,13 +467,10 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
 						per_cpu_ptr(mod->percpu,
 							    get_boot_cpu_id());
 				}
-				preempt_enable();
 				return true;
 			}
 		}
 	}
-
-	preempt_enable();
 	return false;
 }
 
-- 
2.45.2