The modules list and module::kallsyms can be accessed under RCU
assumption.
Use rcu_dereference() to reference the kallsyms pointer in
find_kallsyms_symbol(). Use a RCU section instead of preempt_disable in
callers of find_kallsyms_symbol(). Keep the preempt-disable in
module_address_lookup() due to __module_address().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
kernel/module/kallsyms.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 45846ae4042d1..3f59d04795572 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -257,7 +257,7 @@ static const char *find_kallsyms_symbol(struct module *mod,
{
unsigned int i, best = 0;
unsigned long nextval, bestval;
- struct mod_kallsyms *kallsyms = rcu_dereference_sched(mod->kallsyms);
+ struct mod_kallsyms *kallsyms = rcu_dereference(mod->kallsyms);
struct module_memory *mod_mem;
/* At worse, next value is at end of module */
@@ -329,6 +329,7 @@ int module_address_lookup(unsigned long addr,
int ret = 0;
struct module *mod;
+ guard(rcu)();
preempt_disable();
mod = __module_address(addr);
if (mod) {
@@ -356,7 +357,7 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
{
struct module *mod;
- preempt_disable();
+ guard(rcu)();
list_for_each_entry_rcu(mod, &modules, list) {
if (mod->state == MODULE_STATE_UNFORMED)
continue;
@@ -368,12 +369,10 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
goto out;
strscpy(symname, sym, KSYM_NAME_LEN);
- preempt_enable();
return 0;
}
}
out:
- preempt_enable();
return -ERANGE;
}
--
2.45.2
