linux-kernel - [PATCH v2 20/28] powerpc/ftrace: Use RCU in all users of __module_text

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Message-ID: <20241220174731.514432-21-bigeasy@linutronix.de>
Date: Fri, 20 Dec 2024 18:41:34 +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>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Mark Rutland <mark.rutland@....com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Naveen N Rao <naveen@...nel.org>,
	Nicholas Piggin <npiggin@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-trace-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 20/28] powerpc/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: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Naveen N Rao <naveen@...nel.org>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-trace-kernel@...r.kernel.org
Cc: linuxppc-dev@...ts.ozlabs.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 arch/powerpc/kernel/trace/ftrace.c       | 6 ++----
 arch/powerpc/kernel/trace/ftrace_64_pg.c | 6 ++----
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 5ccd791761e8f..558d7f4e4bea6 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -115,10 +115,8 @@ static unsigned long ftrace_lookup_module_stub(unsigned long ip, unsigned long a
 {
 	struct module *mod = NULL;
 
-	preempt_disable();
-	mod = __module_text_address(ip);
-	preempt_enable();
-
+	scoped_guard(rcu)
+		mod = __module_text_address(ip);
 	if (!mod)
 		pr_err("No module loaded at addr=%lx\n", ip);
 
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 98787376eb87c..531d40f10c8a1 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -120,10 +120,8 @@ static struct module *ftrace_lookup_module(struct dyn_ftrace *rec)
 {
 	struct module *mod;
 
-	preempt_disable();
-	mod = __module_text_address(rec->ip);
-	preempt_enable();
-
+	scoped_guard(rcu)
+		mod = __module_text_address(rec->ip);
 	if (!mod)
 		pr_err("No module loaded at addr=%lx\n", rec->ip);
 
-- 
2.45.2