bpf: Don't use idx variable when registering kfunc dtors

In commit fda01efc6160 ("bpf: Enable cgroups to be used as kptrs"), I
added an 'int idx' variable to kfunc_init() which was meant to
dynamically set the index of the btf id entries of the
'generic_dtor_ids' array. This was done to make the code slightly less
brittle as the struct cgroup * kptr kfuncs such as bpf_cgroup_aquire()
are compiled out if CONFIG_CGROUPS is not defined. This, however, causes
an lkp build warning:

>> kernel/bpf/helpers.c:2005:40: warning: multiple unsequenced
   modifications to 'idx' [-Wunsequenced]
	.btf_id       = generic_dtor_ids[idx++],

Fix the warning by just hard-coding the indices.

Fixes: fda01efc6160 ("bpf: Enable cgroups to be used as kptrs")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221123135253.637525-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index e4e9db301db5cd777c1cbff4e46950bb0ca5dff0..da2681ebb7c39a7a9af92e549118dbe2121bd2f0 100644 (file)
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2019,16 +2019,16 @@ static const struct btf_kfunc_id_set common_kfunc_set = {
 
 static int __init kfunc_init(void)
 {
-       int ret, idx = 0;
+       int ret;
        const struct btf_id_dtor_kfunc generic_dtors[] = {
                {
-                       .btf_id       = generic_dtor_ids[idx++],
-                       .kfunc_btf_id = generic_dtor_ids[idx++]
+                       .btf_id       = generic_dtor_ids[0],
+                       .kfunc_btf_id = generic_dtor_ids[1]
                },
 #ifdef CONFIG_CGROUPS
                {
-                       .btf_id       = generic_dtor_ids[idx++],
-                       .kfunc_btf_id = generic_dtor_ids[idx++]
+                       .btf_id       = generic_dtor_ids[2],
+                       .kfunc_btf_id = generic_dtor_ids[3]
                },
 #endif
        };