[PATCH bpf-next] bpf: Don't use idx variable when registering kfunc dtors

From: David Vernet
Date: Wed Nov 23 2022 - 08:59:08 EST


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@xxxxxxxxx>
Signed-off-by: David Vernet <void@xxxxxxxxxxxxx>
---
kernel/bpf/helpers.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index e4e9db301db5..da2681ebb7c3 100644
--- 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
};
--
2.38.1