[PATCH v2 05/28] module: Use RCU in module_get_kallsym().

[Sebastian Andrzej Siewior]

The modules list and module::kallsyms can be accessed under RCU
assumption.

Iterate the modules with RCU protection, use rcu_dereference() to access
the kallsyms pointer.

Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
 kernel/module/kallsyms.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 3f59d04795572..4eef518204eb5 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -381,13 +381,13 @@ int module_get_kallsym(unsigned int symnum, unsigned long 
*value, char *type,
 {
        struct module *mod;
 
-       preempt_disable();
+       guard(rcu)();
        list_for_each_entry_rcu(mod, &modules, list) {
                struct mod_kallsyms *kallsyms;
 
                if (mod->state == MODULE_STATE_UNFORMED)
                        continue;
-               kallsyms = rcu_dereference_sched(mod->kallsyms);
+               kallsyms = rcu_dereference(mod->kallsyms);
                if (symnum < kallsyms->num_symtab) {
                        const Elf_Sym *sym = &kallsyms->symtab[symnum];
 
@@ -396,12 +396,10 @@ int module_get_kallsym(unsigned int symnum, unsigned long 
*value, char *type,
                        strscpy(name, kallsyms_symbol_name(kallsyms, symnum), 
KSYM_NAME_LEN);
                        strscpy(module_name, mod->name, MODULE_NAME_LEN);
                        *exported = is_exported(name, *value, mod);
-                       preempt_enable();
                        return 0;
                }
                symnum -= kallsyms->num_symtab;
        }
-       preempt_enable();
        return -ERANGE;
 }
 
-- 
2.45.2