From: Jiri Pirko <jiri@resnulli.us>
To: Vlad Buslov <vladbu@mellanox.com>
Cc: netdev@vger.kernel.org, davem@davemloft.net, jhs@mojatatu.com,
xiyou.wangcong@gmail.com, pablo@netfilter.org,
kadlec@blackhole.kfki.hu, fw@strlen.de, ast@kernel.org,
daniel@iogearbox.net, edumazet@google.com, keescook@chromium.org,
linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
coreteam@netfilter.org, kliteyn@mellanox.com
Subject: Re: [PATCH 10/14] net: sched: extend act API for lockless actions
Date: Wed, 16 May 2018 10:56:28 +0200 [thread overview]
Message-ID: <20180516085628.GE1972@nanopsycho> (raw)
In-Reply-To: <vbfbmdg10du.fsf@reg-r-vrt-018-180.mtr.labs.mlnx>
Wed, May 16, 2018 at 10:16:13AM CEST, vladbu@mellanox.com wrote:
>
>On Wed 16 May 2018 at 07:50, Jiri Pirko <jiri@resnulli.us> wrote:
>> Mon, May 14, 2018 at 04:27:11PM CEST, vladbu@mellanox.com wrote:
>>>Implement new action API function to atomically delete action with
>>>specified index and to atomically insert unique action. These functions are
>>>required to implement init and delete functions for specific actions that
>>>do not rely on rtnl lock.
>>>
>>>Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
>>>---
>>> include/net/act_api.h | 2 ++
>>> net/sched/act_api.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>>> 2 files changed, 47 insertions(+)
>>>
>>>diff --git a/include/net/act_api.h b/include/net/act_api.h
>>>index a8c8570..bce0cf1 100644
>>>--- a/include/net/act_api.h
>>>+++ b/include/net/act_api.h
>>>@@ -153,7 +153,9 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
>>> struct tc_action **a, const struct tc_action_ops *ops,
>>> int bind, bool cpustats);
>>> void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a);
>>>+void tcf_idr_insert_unique(struct tc_action_net *tn, struct tc_action *a);
>>>
>>>+int tcf_idr_find_delete(struct tc_action_net *tn, u32 index);
>>> int __tcf_idr_release(struct tc_action *a, bool bind, bool strict);
>>>
>>> static inline int tcf_idr_release(struct tc_action *a, bool bind)
>>>diff --git a/net/sched/act_api.c b/net/sched/act_api.c
>>>index 2772276e..a5193dc 100644
>>>--- a/net/sched/act_api.c
>>>+++ b/net/sched/act_api.c
>>>@@ -330,6 +330,41 @@ bool tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a,
>>> }
>>> EXPORT_SYMBOL(tcf_idr_check);
>>>
>>>+int tcf_idr_find_delete(struct tc_action_net *tn, u32 index)
>>>+{
>>>+ struct tcf_idrinfo *idrinfo = tn->idrinfo;
>>>+ struct tc_action *p;
>>>+ int ret = 0;
>>>+
>>>+ spin_lock_bh(&idrinfo->lock);
>>
>> Why "_bh" is needed here?
>
>Original idr remove function used _bh version so I used it here as well.
>As I already replied to your previous question about idrinfo lock usage,
>I don't see any particular reason for locking with _bh at this point.
>I've contacted the author(Chris Mi) and he said that he just preserved
>locking the same way as it was before he changed hash table to idr for
>action lookup.
>
>You want me to do standalone patch that cleans up idrinfo locking?
Yes please. You can send it separately, not as a part of this patchset.
>
>>
>>
>>>+ p = idr_find(&idrinfo->action_idr, index);
>>>+ if (!p) {
>>>+ spin_unlock(&idrinfo->lock);
>>>+ return -ENOENT;
>>>+ }
>>>+
>>>+ if (!atomic_read(&p->tcfa_bindcnt)) {
>>>+ if (refcount_dec_and_test(&p->tcfa_refcnt)) {
>>>+ struct module *owner = p->ops->owner;
>>>+
>>>+ WARN_ON(p != idr_remove(&idrinfo->action_idr,
>>>+ p->tcfa_index));
>>>+ spin_unlock_bh(&idrinfo->lock);
>>>+
>>>+ tcf_action_cleanup(p);
>>>+ module_put(owner);
>>>+ return 0;
>>>+ }
>>>+ ret = 0;
>>>+ } else {
>>>+ ret = -EPERM;
>>
>> I wonder if "-EPERM" is the best error code for this...
>
>This is what original code returned so I decided to preserve
>compatibility.
Okay.
>
>>
>>
>>>+ }
>>>+
>>>+ spin_unlock_bh(&idrinfo->lock);
>>>+ return ret;
>>>+}
>>>+EXPORT_SYMBOL(tcf_idr_find_delete);
>>>+
>>> int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
>>> struct tc_action **a, const struct tc_action_ops *ops,
>>> int bind, bool cpustats)
>>>@@ -407,6 +442,16 @@ void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a)
>>> }
>>> EXPORT_SYMBOL(tcf_idr_insert);
>>>
>>>+void tcf_idr_insert_unique(struct tc_action_net *tn, struct tc_action *a)
>>>+{
>>>+ struct tcf_idrinfo *idrinfo = tn->idrinfo;
>>>+
>>>+ spin_lock_bh(&idrinfo->lock);
>>>+ WARN_ON(idr_replace(&idrinfo->action_idr, a, a->tcfa_index));
>>
>> Under which condition this WARN_ON is hit?
>
>When idr replace returns non-NULL pointer, which means that somehow
>concurrent insertion of action with same index has happened and we are
>leaking memory.
Is that possible to happen? Meaning, can I as a user cause this by doing
something in a wrong/unexpected way?
>
>By the way I'm still not sure if having this insert unique function is
>warranted or I should just add WARN to regular idr insert. What is your
>opinion on this?
I have to check where you use this.
>
>>
>>
>>>+ spin_unlock_bh(&idrinfo->lock);
>>>+}
>>>+EXPORT_SYMBOL(tcf_idr_insert_unique);
>>>+
>>> void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
>>> struct tcf_idrinfo *idrinfo)
>>> {
>>>--
>>>2.7.5
>>>
>
next prev parent reply other threads:[~2018-05-16 8:56 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-14 14:27 [PATCH 00/14] Modify action API for implementing lockless actions Vlad Buslov
2018-05-14 14:27 ` [PATCH 01/14] net: sched: use rcu for action cookie update Vlad Buslov
2018-05-14 15:10 ` Jiri Pirko
2018-05-14 23:39 ` kbuild test robot
2018-05-14 14:27 ` [PATCH 02/14] net: sched: change type of reference and bind counters Vlad Buslov
2018-05-14 15:11 ` Jiri Pirko
2018-05-19 21:04 ` Marcelo Ricardo Leitner
2018-05-20 10:55 ` Vlad Buslov
2018-05-14 14:27 ` [PATCH 03/14] net: sched: add 'delete' function to action ops Vlad Buslov
2018-05-14 15:12 ` Jiri Pirko
2018-05-14 16:30 ` Jiri Pirko
2018-05-14 14:27 ` [PATCH 04/14] net: sched: implement unlocked action init API Vlad Buslov
2018-05-14 15:16 ` Jiri Pirko
2018-05-19 21:11 ` Marcelo Ricardo Leitner
2018-05-14 14:27 ` [PATCH 05/14] net: sched: always take reference to action Vlad Buslov
2018-05-14 16:23 ` Jiri Pirko
2018-05-14 18:49 ` Vlad Buslov
2018-05-15 8:58 ` Jiri Pirko
2018-05-15 11:52 ` Vlad Buslov
2018-05-15 1:38 ` kbuild test robot
2018-05-15 1:38 ` [RFC PATCH] net: sched: __tcf_idr_check() can be static kbuild test robot
2018-05-14 14:27 ` [PATCH 06/14] net: sched: implement reference counted action release Vlad Buslov
2018-05-14 16:28 ` Jiri Pirko
2018-05-14 16:47 ` Jiri Pirko
2018-05-14 19:07 ` Vlad Buslov
2018-05-15 9:03 ` Jiri Pirko
2018-05-15 9:16 ` Vlad Buslov
2018-05-19 21:43 ` Marcelo Ricardo Leitner
2018-05-20 6:22 ` Jiri Pirko
2018-05-20 10:59 ` Vlad Buslov
2018-05-14 14:27 ` [PATCH 07/14] net: sched: use reference counting action init Vlad Buslov
2018-05-15 11:24 ` Jiri Pirko
2018-05-15 11:32 ` Vlad Buslov
2018-05-15 11:39 ` Jiri Pirko
2018-05-15 11:41 ` Vlad Buslov
2018-05-15 11:57 ` Jiri Pirko
2018-05-15 12:00 ` Vlad Buslov
2018-05-14 14:27 ` [PATCH 08/14] net: sched: account for temporary action reference Vlad Buslov
2018-05-16 7:12 ` Jiri Pirko
2018-05-14 14:27 ` [PATCH 09/14] net: sched: don't release reference on action overwrite Vlad Buslov
2018-05-16 7:43 ` Jiri Pirko
2018-05-16 7:47 ` Vlad Buslov
2018-05-16 7:50 ` Jiri Pirko
2018-05-19 21:52 ` Marcelo Ricardo Leitner
2018-05-20 18:42 ` Vlad Buslov
2018-05-14 14:27 ` [PATCH 10/14] net: sched: extend act API for lockless actions Vlad Buslov
2018-05-16 7:50 ` Jiri Pirko
2018-05-16 8:16 ` Vlad Buslov
2018-05-16 8:56 ` Jiri Pirko [this message]
2018-05-16 9:39 ` Vlad Buslov
2018-05-19 22:17 ` Marcelo Ricardo Leitner
2018-05-14 14:27 ` [PATCH 11/14] net: core: add new/replace rate estimator lock parameter Vlad Buslov
2018-05-16 9:54 ` Jiri Pirko
2018-05-16 10:00 ` Vlad Buslov
2018-05-16 10:11 ` Jiri Pirko
2018-05-14 14:27 ` [PATCH 12/14] net: sched: retry action check-insert on concurrent modification Vlad Buslov
2018-05-16 9:59 ` Jiri Pirko
2018-05-16 11:55 ` Vlad Buslov
2018-05-16 12:26 ` Jiri Pirko
2018-05-16 12:43 ` Vlad Buslov
2018-05-16 13:21 ` Jiri Pirko
2018-05-16 13:52 ` Vlad Buslov
2018-05-16 14:13 ` Jiri Pirko
2018-05-16 14:26 ` Vlad Buslov
2018-05-16 14:55 ` Jiri Pirko
2018-05-19 22:35 ` Marcelo Ricardo Leitner
2018-05-14 14:27 ` [PATCH 13/14] net: sched: use unique idr insert function in unlocked actions Vlad Buslov
2018-05-16 9:50 ` Jiri Pirko
2018-05-16 9:54 ` Vlad Buslov
2018-05-19 22:20 ` Marcelo Ricardo Leitner
2018-05-20 21:13 ` Or Gerlitz
2018-05-20 21:33 ` Marcelo Ricardo Leitner
2018-05-20 21:40 ` Or Gerlitz
2018-05-20 22:43 ` Marcelo Ricardo Leitner
2018-05-14 14:27 ` [PATCH 14/14] net: sched: implement delete for all actions Vlad Buslov
2018-05-16 9:48 ` Jiri Pirko
2018-05-16 9:58 ` Vlad Buslov
2018-05-19 22:45 ` Marcelo Ricardo Leitner
2018-05-14 18:03 ` [PATCH 00/14] Modify action API for implementing lockless actions Jamal Hadi Salim
2018-05-14 20:46 ` Vlad Buslov
2018-05-15 18:25 ` Jamal Hadi Salim
2018-05-15 21:21 ` Vlad Buslov
2018-05-15 8:20 ` Jiri Pirko
2018-05-24 23:34 ` Cong Wang
2018-05-25 20:39 ` Vlad Buslov
2018-05-25 21:40 ` Cong Wang
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