LoongArch: ftrace: Use RCU in all users of __module_text_address().

__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
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250108090457.512198-20-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>

diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 25c9a4cfd5fa9284201d8624f37acd1944a05969..d5d81d74034c859c1a2ad09667135318c67661f9 100644 (file)
--- 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))