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[v3,19/28] LoongArch: ftrace: Use RCU in all users of __module_text_address().

Message ID 20250108090457.512198-20-bigeasy@linutronix.de (mailing list archive)
State New
Headers show
Series module: Use RCU instead of RCU-sched. | expand

Commit Message

Sebastian Sewior Jan. 8, 2025, 9:04 a.m. UTC 
__module_text_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

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

Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: linux-trace-kernel@vger.kernel.org
Cc: loongarch@lists.linux.dev
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 arch/loongarch/kernel/ftrace_dyn.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)
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Patch

diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 18056229e22e4..5b7b8ac13e350 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -85,14 +85,13 @@  static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod
 	 * dealing with an out-of-range condition, we can assume it
 	 * is due to a module being loaded far away from the kernel.
 	 *
-	 * NOTE: __module_text_address() must be called with preemption
-	 * disabled, but we can rely on ftrace_lock to ensure that 'mod'
+	 * NOTE: __module_text_address() must be called within a RCU read
+	 * section, but we can rely on ftrace_lock to ensure that 'mod'
 	 * retains its validity throughout the remainder of this code.
 	 */
 	if (!mod) {
-		preempt_disable();
-		mod = __module_text_address(pc);
-		preempt_enable();
+		scoped_guard(rcu)
+			mod = __module_text_address(pc);
 	}
 
 	if (WARN_ON(!mod))