[PATCH v2 net 1/1] net sched actions: fix GETing actions

[PATCH v2 net 1/1] net sched actions: fix GETing actions

[Jamal Hadi Salim]

From: Jamal Hadi Salim <jhs@mojatatu.com>

With the batch changes that translated transient actions into
a temporary list we lost in the translation the fact that
tcf_action_destroy() will eventually delete the action from
the permanent location if the refcount is zero.

Example of what broke:
...add a gact action to drop
sudo $TC actions add action drop index 10
...now retrieve it, looks good
sudo $TC actions get action gact index 10
...retrieve it again and find it is gone!
sudo $TC actions get action gact index 10

Fixes:
22dc13c837c3 ("net_sched: convert tcf_exts from list to pointer array"),
824a7e8863b3 ("net_sched: remove an unnecessary list_del()")
f07fed82ad79 ("net_sched: remove the leftover cleanup_a()")

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 net/sched/act_api.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index d09d068..63b8167 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -592,6 +592,16 @@ err_out:
 	return ERR_PTR(err);
 }
 
+static void cleanup_a(struct list_head *actions, int ovr)
+{
+	struct tc_action *a, *tmp;
+
+	list_for_each_entry_safe(a, tmp, actions, list) {
+		if (ovr)
+			a->tcfa_refcnt-=1;
+	}
+}
+
 int tcf_action_init(struct net *net, struct nlattr *nla,
 				  struct nlattr *est, char *name, int ovr,
 				  int bind, struct list_head *actions)
@@ -612,8 +622,15 @@ int tcf_action_init(struct net *net, struct nlattr *nla,
 			goto err;
 		}
 		act->order = i;
+		if (ovr)
+			act->tcfa_refcnt+=1;
 		list_add_tail(&act->list, actions);
 	}
+
+	/* Remove the temp refcnt which was necessary to protect against
+	 * destroying an existing action which was being replaced
+	 */
+	cleanup_a(actions, ovr);
 	return 0;
 
 err:
@@ -883,6 +900,8 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
 			goto err;
 		}
 		act->order = i;
+		if (event == RTM_GETACTION)
+			act->tcfa_refcnt+=1;
 		list_add_tail(&act->list, &actions);
 	}
 
-- 
1.9.1

Re: [PATCH v2 net 1/1] net sched actions: fix GETing actions

[Cong Wang]

On Mon, Sep 12, 2016 at 3:21 AM, Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> With the batch changes that translated transient actions into
> a temporary list we lost in the translation the fact that
> tcf_action_destroy() will eventually delete the action from
> the permanent location if the refcount is zero.
>
> Example of what broke:
> ...add a gact action to drop
> sudo $TC actions add action drop index 10
> ...now retrieve it, looks good
> sudo $TC actions get action gact index 10
> ...retrieve it again and find it is gone!
> sudo $TC actions get action gact index 10
>
> Fixes:
> 22dc13c837c3 ("net_sched: convert tcf_exts from list to pointer array"),
> 824a7e8863b3 ("net_sched: remove an unnecessary list_del()")
> f07fed82ad79 ("net_sched: remove the leftover cleanup_a()")
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
> ---
>  net/sched/act_api.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
> index d09d068..63b8167 100644
> --- a/net/sched/act_api.c
> +++ b/net/sched/act_api.c
> @@ -592,6 +592,16 @@ err_out:
>         return ERR_PTR(err);
>  }
>
> +static void cleanup_a(struct list_head *actions, int ovr)
> +{
> +       struct tc_action *a, *tmp;
> +
> +       list_for_each_entry_safe(a, tmp, actions, list) {


No need the safe version.

> +               if (ovr)
> +                       a->tcfa_refcnt-=1;

How about tcfa_bindcnt?

I hate to point out coding style issue, but since you need to update
the patch anyway, please add two spaces surround '-='.

I think checkpatch.pl should be able to catch this.

> +       }
> +}
> +
>  int tcf_action_init(struct net *net, struct nlattr *nla,
>                                   struct nlattr *est, char *name, int ovr,
>                                   int bind, struct list_head *actions)
> @@ -612,8 +622,15 @@ int tcf_action_init(struct net *net, struct nlattr *nla,
>                         goto err;
>                 }
>                 act->order = i;
> +               if (ovr)

Need to check this boolean? It looks like we need this for !ovr case too?


> +                       act->tcfa_refcnt+=1;


Ditto for coding style.

>                 list_add_tail(&act->list, actions);
>         }
> +
> +       /* Remove the temp refcnt which was necessary to protect against
> +        * destroying an existing action which was being replaced
> +        */
> +       cleanup_a(actions, ovr);
>         return 0;
>
>  err:
> @@ -883,6 +900,8 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>                         goto err;
>                 }
>                 act->order = i;
> +               if (event == RTM_GETACTION)
> +                       act->tcfa_refcnt+=1;

Ditto.


>                 list_add_tail(&act->list, &actions);
>         }
>


Thanks.

Re: [PATCH v2 net 1/1] net sched actions: fix GETing actions

[Jamal Hadi Salim]

On 16-09-12 01:18 PM, Cong Wang wrote:
> On Mon, Sep 12, 2016 at 3:21 AM, Jamal Hadi Salim <jhs@mojatatu.com> wrote:


>> +               if (ovr)
>> +                       a->tcfa_refcnt-=1;
>
> How about tcfa_bindcnt?

We dont touch it when mucking around only with actions (as is in
this case).


>> +       }
>> +}
>> +
>>  int tcf_action_init(struct net *net, struct nlattr *nla,
>>                                   struct nlattr *est, char *name, int ovr,
>>                                   int bind, struct list_head *actions)
>> @@ -612,8 +622,15 @@ int tcf_action_init(struct net *net, struct nlattr *nla,
>>                         goto err;
>>                 }
>>                 act->order = i;
>> +               if (ovr)
>
> Need to check this boolean? It looks like we need this for !ovr case too?
>

They are fine if they didnt exist.

I will fix the coding style issues and submit.

cheers,
jamal

Re: [PATCH v2 net 1/1] net sched actions: fix GETing actions

[Cong Wang]

On Mon, Sep 12, 2016 at 3:21 AM, Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> With the batch changes that translated transient actions into
> a temporary list we lost in the translation the fact that
> tcf_action_destroy() will eventually delete the action from
> the permanent location if the refcount is zero.
>
> Example of what broke:
> ...add a gact action to drop
> sudo $TC actions add action drop index 10
> ...now retrieve it, looks good
> sudo $TC actions get action gact index 10
> ...retrieve it again and find it is gone!
> sudo $TC actions get action gact index 10
>
> Fixes:
> 22dc13c837c3 ("net_sched: convert tcf_exts from list to pointer array"),
> 824a7e8863b3 ("net_sched: remove an unnecessary list_del()")
> f07fed82ad79 ("net_sched: remove the leftover cleanup_a()")
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>

Maybe the changelog/comment needs slightly improved,
but that is a very minor issue. So,

Acked-by: Cong Wang <xiyou.wangcong@gmail.com>