Re: [PATCH 09/14] net: sched: don't release reference on action overwrite

Jiri Pirko
2018-05-16T07:50:35Z

Wed, May 16, 2018 at 09:47:32AM CEST, vladbu@mellanox.com wrote:
>
>On Wed 16 May 2018 at 07:43, Jiri Pirko <jiri@resnulli.us> wrote:
>> Mon, May 14, 2018 at 04:27:10PM CEST, vladbu@mellanox.com wrote:
>>>Return from action init function with reference to action taken,
>>>even when overwriting existing action.
>>>
>>>Action init API initializes its fourth argument (pointer to pointer to
>>>tc action) to either existing action with same index or newly created
>>>action. In case of existing index(and bind argument is zero), init
>>>function returns without incrementing action reference counter. Caller
>>>of action init then proceeds working with action without actually
>>>holding reference to it. This means that action could be deleted
>>>concurrently. To prevent such scenario this patch changes action init
>>
>> Be imperative to the codebase in the patch description.
>>
>>
>>>behavior to always take reference to action before returning
>>>successfully.
>>
>> Where's the balance? Who does the release instead? I'm probably missing
>> something.
>
>I've resplit these patches for V2 to always do take/release in same
>patch.

Good. Thanks.

>
>>
>>>
>>>Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
>>>---
>>> net/sched/act_bpf.c | 8 ++++----
>>> net/sched/act_connmark.c | 5 +++--
>>> net/sched/act_csum.c | 8 ++++----
>>> net/sched/act_gact.c | 5 +++--
>>> net/sched/act_ife.c | 12 +++++-------
>>> net/sched/act_ipt.c | 5 +++--
>>> net/sched/act_mirred.c | 5 ++---
>>> net/sched/act_nat.c | 5 +++--
>>> net/sched/act_pedit.c | 5 +++--
>>> net/sched/act_police.c | 8 +++-----
>>> net/sched/act_sample.c | 8 +++-----
>>> net/sched/act_simple.c | 5 +++--
>>> net/sched/act_skbedit.c | 5 +++--
>>> net/sched/act_skbmod.c | 8 +++-----
>>> net/sched/act_tunnel_key.c | 8 +++-----
>>> net/sched/act_vlan.c | 8 +++-----
>>> 16 files changed, 51 insertions(+), 57 deletions(-)
>>>
>>>diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
>>>index 5d95c43..5554bf7 100644
>>>--- a/net/sched/act_bpf.c
>>>+++ b/net/sched/act_bpf.c
>>>@@ -311,9 +311,10 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla,
>>> if (bind)
>>> return 0;
>>>
>>>- tcf_idr_release(*act, bind);
>>>- if (!replace)
>>>+ if (!replace) {
>>>+ tcf_idr_release(*act, bind);
>>> return -EEXIST;
>>>+ }
>>> }
>>>
>>> is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
>>
>> [...]
>