Re: [PATCH v4 net 1/1] net sched actions: fix GETing actions

[David Miller]

From: Jamal Hadi Salim 
Date: Fri, 16 Sep 2016 16:27:04 -0400

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

Please use multiple "Fixes: " lines to reference multiple commits, like so:


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

> +static void cleanup_a(struct list_head *actions, int ovr)
> +{
> + struct tc_action *a;
> +
> + list_for_each_entry(a, actions, list) {
> + if (ovr)
> + a->tcfa_refcnt--;
> + }
> +}

Please move the invariant test outside of the loop, like so:

if (!ovr)
return;
list_for_each_entry(a, actions, list)
a->tcfa_refcnt--;

Thanks.

[PATCH v4 net 1/1] net sched actions: fix GETing actions

[Jamal Hadi Salim]

From: Jamal Hadi Salim 

With the batch changes that translated transient actions into
a temporary list lost in the translation was 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:
commit 22dc13c837c3 ("net_sched: convert tcf_exts from list to pointer array"),
commit 824a7e8863b3 ("net_sched: remove an unnecessary list_del()")
commit f07fed82ad79 ("net_sched: remove the leftover cleanup_a()")

Signed-off-by: Jamal Hadi Salim 
Acked-by: Cong Wang 
---
 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..e1c0ce1 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;
+
+   list_for_each_entry(a, actions, list) {
+   if (ovr)
+   a->tcfa_refcnt--;
+   }
+}
+
 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++;
list_add_tail(>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++;
list_add_tail(>list, );
}
 
-- 
1.9.1