From: Vlad Buslov <vladbu@mellanox.com>
To: Cong Wang <xiyou.wangcong@gmail.com>, Jiri Pirko <jiri@resnulli.us>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next 01/12] net: sched: flower: don't check for rtnl on head dereference
Date: Thu, 28 Feb 2019 18:35:31 +0000 [thread overview]
Message-ID: <vbfbm2vzs0u.fsf@mellanox.com> (raw)
In-Reply-To: <CAM_iQpWfOoKxipJnha72e6dGv5RHEuDQvCjqU6nL1b_2tQMn9g@mail.gmail.com>
On Thu 28 Feb 2019 at 00:49, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Tue, Feb 26, 2019 at 6:57 AM Vlad Buslov <vladbu@mellanox.com> wrote:
>>
>>
>> On Mon 25 Feb 2019 at 22:39, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> > On Mon, Feb 25, 2019 at 8:11 AM Vlad Buslov <vladbu@mellanox.com> wrote:
>> >>
>> >>
>> >> On Fri 22 Feb 2019 at 19:32, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> >> >
>> >> > So if it is no longer RCU any more, why do you still use
>> >> > rcu_dereference_protected()? That is, why not just deref it as a raw
>> >> > pointer?
>> >
>> >
>> > Any answer for this question?
>>
>> I decided that since there is neither possibility of concurrent pointer
>> assignment nor deallocation of object that it points to, most performant
>> solution would be using rcu_dereference_protected() which is the only
>> RCU dereference helper that doesn't use READ_ONCE. I now understand that
>> this is confusing (and most likely doesn't provide any noticeable
>> performance improvement anyway!) and will change this patch to use
>> rcu_dereference_raw() as you suggest.
>
> Yeah, please make sure sparse is happy with that. :)
I checked my flower change with sparse. It produced a lot of warnings,
some of which are several years old. None in the code I changed though:
CHECK net/sched/cls_flower.c
net/sched/cls_flower.c:200:20: warning: cast from restricted __be16
net/sched/cls_flower.c:200:20: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:200:20: expected unsigned short [usertype] val
net/sched/cls_flower.c:200:20: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:200:20: warning: cast from restricted __be16
net/sched/cls_flower.c:200:20: warning: cast from restricted __be16
net/sched/cls_flower.c:201:20: warning: cast from restricted __be16
net/sched/cls_flower.c:201:20: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:201:20: expected unsigned short [usertype] val
net/sched/cls_flower.c:201:20: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:201:20: warning: cast from restricted __be16
net/sched/cls_flower.c:201:20: warning: cast from restricted __be16
net/sched/cls_flower.c:202:19: warning: cast from restricted __be16
net/sched/cls_flower.c:202:19: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:202:19: expected unsigned short [usertype] val
net/sched/cls_flower.c:202:19: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:202:19: warning: cast from restricted __be16
net/sched/cls_flower.c:202:19: warning: cast from restricted __be16
net/sched/cls_flower.c:203:19: warning: cast from restricted __be16
net/sched/cls_flower.c:203:19: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:203:19: expected unsigned short [usertype] val
net/sched/cls_flower.c:203:19: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:203:19: warning: cast from restricted __be16
net/sched/cls_flower.c:203:19: warning: cast from restricted __be16
net/sched/cls_flower.c:206:21: warning: cast from restricted __be16
net/sched/cls_flower.c:206:21: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:206:21: expected unsigned short [usertype] val
net/sched/cls_flower.c:206:21: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:206:21: warning: cast from restricted __be16
net/sched/cls_flower.c:206:21: warning: cast from restricted __be16
net/sched/cls_flower.c:206:21: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:206:42: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:207:21: warning: cast from restricted __be16
net/sched/cls_flower.c:207:21: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:207:21: expected unsigned short [usertype] val
net/sched/cls_flower.c:207:21: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:207:21: warning: cast from restricted __be16
net/sched/cls_flower.c:207:21: warning: cast from restricted __be16
net/sched/cls_flower.c:207:21: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:207:42: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:223:20: warning: cast from restricted __be16
net/sched/cls_flower.c:223:20: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:223:20: expected unsigned short [usertype] val
net/sched/cls_flower.c:223:20: got restricted __be16 [usertype] src
net/sched/cls_flower.c:223:20: warning: cast from restricted __be16
net/sched/cls_flower.c:223:20: warning: cast from restricted __be16
net/sched/cls_flower.c:224:20: warning: cast from restricted __be16
net/sched/cls_flower.c:224:20: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:224:20: expected unsigned short [usertype] val
net/sched/cls_flower.c:224:20: got restricted __be16 [usertype] src
net/sched/cls_flower.c:224:20: warning: cast from restricted __be16
net/sched/cls_flower.c:224:20: warning: cast from restricted __be16
net/sched/cls_flower.c:225:19: warning: cast from restricted __be16
net/sched/cls_flower.c:225:19: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:225:19: expected unsigned short [usertype] val
net/sched/cls_flower.c:225:19: got restricted __be16 [usertype] src
net/sched/cls_flower.c:225:19: warning: cast from restricted __be16
net/sched/cls_flower.c:225:19: warning: cast from restricted __be16
net/sched/cls_flower.c:226:19: warning: cast from restricted __be16
net/sched/cls_flower.c:226:19: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:226:19: expected unsigned short [usertype] val
net/sched/cls_flower.c:226:19: got restricted __be16 [usertype] src
net/sched/cls_flower.c:226:19: warning: cast from restricted __be16
net/sched/cls_flower.c:226:19: warning: cast from restricted __be16
net/sched/cls_flower.c:229:21: warning: cast from restricted __be16
net/sched/cls_flower.c:229:21: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:229:21: expected unsigned short [usertype] val
net/sched/cls_flower.c:229:21: got restricted __be16 [usertype] src
net/sched/cls_flower.c:229:21: warning: cast from restricted __be16
net/sched/cls_flower.c:229:21: warning: cast from restricted __be16
net/sched/cls_flower.c:229:21: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:229:42: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:230:21: warning: cast from restricted __be16
net/sched/cls_flower.c:230:21: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:230:21: expected unsigned short [usertype] val
net/sched/cls_flower.c:230:21: got restricted __be16 [usertype] src
net/sched/cls_flower.c:230:21: warning: cast from restricted __be16
net/sched/cls_flower.c:230:21: warning: cast from restricted __be16
net/sched/cls_flower.c:230:21: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:230:42: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:744:14: warning: cast from restricted __be16
net/sched/cls_flower.c:744:14: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:744:14: expected unsigned short [usertype] val
net/sched/cls_flower.c:744:14: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:744:14: warning: cast from restricted __be16
net/sched/cls_flower.c:744:14: warning: cast from restricted __be16
net/sched/cls_flower.c:744:40: warning: cast from restricted __be16
net/sched/cls_flower.c:744:40: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:744:40: expected unsigned short [usertype] val
net/sched/cls_flower.c:744:40: got restricted __be16 [usertype] dst
net/sched/cls_flower.c:744:40: warning: cast from restricted __be16
net/sched/cls_flower.c:744:40: warning: cast from restricted __be16
net/sched/cls_flower.c:744:14: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:744:40: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:746:15: warning: cast from restricted __be16
net/sched/cls_flower.c:746:15: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:746:15: expected unsigned short [usertype] val
net/sched/cls_flower.c:746:15: got restricted __be16 [usertype] src
net/sched/cls_flower.c:746:15: warning: cast from restricted __be16
net/sched/cls_flower.c:746:15: warning: cast from restricted __be16
net/sched/cls_flower.c:746:41: warning: cast from restricted __be16
net/sched/cls_flower.c:746:41: warning: incorrect type in argument 1 (different base types)
net/sched/cls_flower.c:746:41: expected unsigned short [usertype] val
net/sched/cls_flower.c:746:41: got restricted __be16 [usertype] src
net/sched/cls_flower.c:746:41: warning: cast from restricted __be16
net/sched/cls_flower.c:746:41: warning: cast from restricted __be16
net/sched/cls_flower.c:746:15: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:746:41: warning: restricted __be16 degrades to integer
net/sched/cls_flower.c:830:15: warning: cast to restricted __be32
net/sched/cls_flower.c:830:15: warning: cast to restricted __be32
net/sched/cls_flower.c:830:15: warning: cast to restricted __be32
net/sched/cls_flower.c:830:15: warning: cast to restricted __be32
net/sched/cls_flower.c:830:15: warning: cast to restricted __be32
net/sched/cls_flower.c:830:15: warning: cast to restricted __be32
net/sched/cls_flower.c:831:16: warning: cast to restricted __be32
net/sched/cls_flower.c:831:16: warning: cast to restricted __be32
net/sched/cls_flower.c:831:16: warning: cast to restricted __be32
net/sched/cls_flower.c:831:16: warning: cast to restricted __be32
net/sched/cls_flower.c:831:16: warning: cast to restricted __be32
net/sched/cls_flower.c:831:16: warning: cast to restricted __be32
Cong, Jiri, do you want me to send patch that fixes all of these first?
Regards,
Vlad
next prev parent reply other threads:[~2019-02-28 18:35 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 7:47 [PATCH net-next 00/12] Refactor flower classifier to remove dependency on rtnl lock Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 01/12] net: sched: flower: don't check for rtnl on head dereference Vlad Buslov
2019-02-18 19:08 ` Cong Wang
2019-02-19 9:45 ` Vlad Buslov
2019-02-20 22:33 ` Cong Wang
2019-02-21 17:45 ` Vlad Buslov
2019-02-22 19:32 ` Cong Wang
2019-02-25 16:11 ` Vlad Buslov
2019-02-25 22:39 ` Cong Wang
2019-02-26 14:57 ` Vlad Buslov
2019-02-28 0:49 ` Cong Wang
2019-02-28 18:35 ` Vlad Buslov [this message]
2019-03-02 0:51 ` Cong Wang
2019-02-14 7:47 ` [PATCH net-next 02/12] net: sched: flower: refactor fl_change Vlad Buslov
2019-02-14 20:34 ` Stefano Brivio
2019-02-15 10:38 ` Vlad Buslov
2019-02-15 10:47 ` Stefano Brivio
2019-02-15 16:25 ` Vlad Buslov
2019-02-18 18:20 ` Stefano Brivio
2019-02-14 7:47 ` [PATCH net-next 03/12] net: sched: flower: introduce reference counting for filters Vlad Buslov
2019-02-14 20:34 ` Stefano Brivio
2019-02-15 11:22 ` Vlad Buslov
2019-02-15 12:32 ` Stefano Brivio
2019-02-14 7:47 ` [PATCH net-next 04/12] net: sched: flower: track filter deletion with flag Vlad Buslov
2019-02-14 20:49 ` Stefano Brivio
2019-02-15 15:54 ` Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 05/12] net: sched: flower: add reference counter to flower mask Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 06/12] net: sched: flower: handle concurrent mask insertion Vlad Buslov
2019-02-15 22:46 ` Stefano Brivio
2019-02-14 7:47 ` [PATCH net-next 07/12] net: sched: flower: protect masks list with spinlock Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 08/12] net: sched: flower: handle concurrent filter insertion in fl_change Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf proto deletion Vlad Buslov
2019-02-18 20:47 ` Cong Wang
2019-02-19 14:08 ` Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 10/12] net: sched: flower: protect flower classifier state with spinlock Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 11/12] net: sched: flower: track rtnl lock state Vlad Buslov
2019-02-15 22:46 ` Stefano Brivio
2019-02-18 9:35 ` Vlad Buslov
2019-02-14 7:47 ` [PATCH net-next 12/12] net: sched: flower: set unlocked flag for flower proto ops Vlad Buslov
2019-02-18 19:27 ` Cong Wang
2019-02-19 10:15 ` Vlad Buslov
2019-02-20 22:36 ` Cong Wang
2019-02-18 19:15 ` [PATCH net-next 00/12] Refactor flower classifier to remove dependency on rtnl lock Cong Wang
2019-02-19 10:00 ` Vlad Buslov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=vbfbm2vzs0u.fsf@mellanox.com \
--to=vladbu@mellanox.com \
--cc=davem@davemloft.net \
--cc=jhs@mojatatu.com \
--cc=jiri@resnulli.us \
--cc=netdev@vger.kernel.org \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.