From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 8 Jan 2025 09:04:40 +0000 (+0100)
Subject: module: Use RCU in __is_module_percpu_address().
X-Git-Tag: v6.15-rc1~94^2~21
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2bee017741f2890131da2fac96c3f2b64cb947b0;p=thirdparty%2Flinux.git

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@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250108090457.512198-12-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---

diff --git a/kernel/module/main.c b/kernel/module/main.c
index af7ca713eff0a..5d6f44c09bec2 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;
 }