linux-kernel - [PATCH v2 22/28] jump_label: Use RCU in all users of __module

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Message-ID: <20241220174731.514432-23-bigeasy@linutronix.de>
Date: Fri, 20 Dec 2024 18:41:36 +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>,
	Ard Biesheuvel <ardb@...nel.org>,
	Jason Baron <jbaron@...mai.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH v2 22/28] jump_label: Use RCU in all users of __module_address().

__module_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

Replace the preempt_disable() section around __module_address() with RCU.

Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/jump_label.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 93a822d3c468c..7fcf4017cb383 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -746,9 +746,9 @@ static int jump_label_add_module(struct module *mod)
 				kfree(jlm);
 				return -ENOMEM;
 			}
-			preempt_disable();
-			jlm2->mod = __module_address((unsigned long)key);
-			preempt_enable();
+			scoped_guard(rcu)
+				jlm2->mod = __module_address((unsigned long)key);
+
 			jlm2->entries = static_key_entries(key);
 			jlm2->next = NULL;
 			static_key_set_mod(key, jlm2);
@@ -906,13 +906,13 @@ static void jump_label_update(struct static_key *key)
 		return;
 	}
 
-	preempt_disable();
-	mod = __module_address((unsigned long)key);
-	if (mod) {
-		stop = mod->jump_entries + mod->num_jump_entries;
-		init = mod->state == MODULE_STATE_COMING;
+	scoped_guard(rcu) {
+		mod = __module_address((unsigned long)key);
+		if (mod) {
+			stop = mod->jump_entries + mod->num_jump_entries;
+			init = mod->state == MODULE_STATE_COMING;
+		}
 	}
-	preempt_enable();
 #endif
 	entry = static_key_entries(key);
 	/* if there are no users, entry can be NULL */
-- 
2.45.2