bpf: Always raise reference in btf_get_module_btf

Align it with helpers like bpf_find_btf_id, so all functions returning
BTF in out parameter follow the same rule of raising reference
consistently, regardless of module or vmlinux BTF.

Adjust existing callers to handle the change accordinly.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220317115957.3193097-10-memxor@gmail.com

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 17b9adcd88d3e232e555f26c7533161096401793..6d9e711cb5d4063f6293a518cd1f3a029efb015c 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6572,20 +6572,23 @@ struct module *btf_try_get_module(const struct btf *btf)
        return res;
 }
 
-/* Returns struct btf corresponding to the struct module
- *
- * This function can return NULL or ERR_PTR. Note that caller must
- * release reference for struct btf iff btf_is_module is true.
+/* Returns struct btf corresponding to the struct module.
+ * This function can return NULL or ERR_PTR.
  */
 static struct btf *btf_get_module_btf(const struct module *module)
 {
-       struct btf *btf = NULL;
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
        struct btf_module *btf_mod, *tmp;
 #endif
+       struct btf *btf = NULL;
+
+       if (!module) {
+               btf = bpf_get_btf_vmlinux();
+               if (!IS_ERR(btf))
+                       btf_get(btf);
+               return btf;
+       }
 
-       if (!module)
-               return bpf_get_btf_vmlinux();
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
        mutex_lock(&btf_module_mutex);
        list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
@@ -6823,9 +6826,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 
        hook = bpf_prog_type_to_kfunc_hook(prog_type);
        ret = btf_populate_kfunc_set(btf, hook, kset);
-       /* reference is only taken for module BTF */
-       if (btf_is_module(btf))
-               btf_put(btf);
+       btf_put(btf);
        return ret;
 }
 EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);