linux-kernel - [PATCH v2 07/28] module: Use RCU in __find_kallsyms_symbol

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Message-ID: <20241220174731.514432-8-bigeasy@linutronix.de>
Date: Fri, 20 Dec 2024 18:41:21 +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>
Subject: [PATCH v2 07/28] module: Use RCU in __find_kallsyms_symbol_value().

module::kallsyms can be accessed under RCU assumption.

Use rcu_dereference() to access module::kallsyms.
Update callers.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/module/kallsyms.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 3cba9f933b24f..e3c55bc879c11 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -407,7 +407,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 static unsigned long __find_kallsyms_symbol_value(struct module *mod, const char *name)
 {
 	unsigned int i;
-	struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
+	struct mod_kallsyms *kallsyms = rcu_dereference(mod->kallsyms);
 
 	for (i = 0; i < kallsyms->num_symtab; i++) {
 		const Elf_Sym *sym = &kallsyms->symtab[i];
@@ -447,24 +447,15 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
 /* Look for this name: can be of form module:name. */
 unsigned long module_kallsyms_lookup_name(const char *name)
 {
-	unsigned long ret;
-
 	/* Don't lock: we're in enough trouble already. */
 	guard(rcu)();
-	preempt_disable();
-	ret = __module_kallsyms_lookup_name(name);
-	preempt_enable();
-	return ret;
+	return __module_kallsyms_lookup_name(name);
 }
 
 unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
 {
-	unsigned long ret;
-
-	preempt_disable();
-	ret = __find_kallsyms_symbol_value(mod, name);
-	preempt_enable();
-	return ret;
+	guard(rcu)();
+	return __find_kallsyms_symbol_value(mod, name);
 }
 
 int module_kallsyms_on_each_symbol(const char *modname,
-- 
2.45.2