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SubjectRe: [BUG] act_ife: sleeping functions called in atomic context
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On 16-06-16 05:43 PM, Cong Wang wrote:
> On Thu, Jun 16, 2016 at 1:50 PM, Alexey Khoroshilov
> <khoroshilov@ispras.ru> wrote:
>> tcf_ife_init() contains a big chunk of code executed with
>> ife->tcf_lock spinlock held. But that code contains several calls
>> to sleeping functions:
>> populate_metalist() and use_all_metadata()
>> -> add_metainfo()
>> -> find_ife_oplist(metaid)
>> -> read_lock()
>> -> try_module_get(o->owner)
>> -> kzalloc(sizeof(*mi), GFP_KERNEL);
>
> Hmm, we don't need to hold that spinlock when we create a new ife action,
> since we haven't inserted it yet. We do need it when we modify an existing
> one. So I am thinking if we can refactor that code to avoid spinlock
> whenever possible.
>

Does attached (compile tested) patch help?

>> -> ops->alloc(mi, metaval);
>> -> module_put(ops->owner);
>> _tcf_ife_cleanup()
>> -> module_put()
>>
>> The same problem is actual for tcf_ife_cleanup() as well.
>>
>
> Huh? Both module_put() and kfree() should not sleep, right?
>

I dont think there is any sleeping there ;->

cheers,
jamal
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index 6bbc518..e341bef 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -302,7 +302,9 @@ static int add_metainfo(struct tcf_ife_info *ife, u32 metaid, void *metaval,
}
}

+ spin_lock_bh(&ife->tcf_lock);
list_add_tail(&mi->metalist, &ife->metalist);
+ spin_unlock_bh(&ife->tcf_lock);

return ret;
}
@@ -474,7 +476,6 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla,
saddr = nla_data(tb[TCA_IFE_SMAC]);
}

- spin_lock_bh(&ife->tcf_lock);
ife->tcf_action = parm->action;

if (parm->flags & IFE_ENCODE) {
@@ -504,7 +505,6 @@ metadata_parse_err:
if (ret == ACT_P_CREATED)
_tcf_ife_cleanup(a, bind);

- spin_unlock_bh(&ife->tcf_lock);
return err;
}

@@ -523,13 +523,10 @@ metadata_parse_err:
if (ret == ACT_P_CREATED)
_tcf_ife_cleanup(a, bind);

- spin_unlock_bh(&ife->tcf_lock);
return err;
}
}

- spin_unlock_bh(&ife->tcf_lock);
-
if (ret == ACT_P_CREATED)
tcf_hash_insert(tn, a);
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