From: Steffen Klassert <steffen.klassert@secunet.com>
To: Yuehaibing <yuehaibing@huawei.com>
Cc: <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
<kuba@kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting
Date: Mon, 6 Apr 2020 11:03:27 +0200 [thread overview]
Message-ID: <20200406090327.GF13121@gauss3.secunet.de> (raw)
In-Reply-To: <1d3596fb-c7e3-16c9-f48f-fe58e9a2569a@huawei.com>
On Mon, Mar 30, 2020 at 10:05:32PM +0800, Yuehaibing wrote:
> On 2020/3/28 19:23, Steffen Klassert wrote:
> > On Fri, Mar 27, 2020 at 08:34:43PM +0800, YueHaibing wrote:
> >> Since commit 7cb8a93968e3 ("xfrm: Allow inserting policies with matching
> >> mark and different priorities"), we allow duplicate policies with
> >> different priority, this WARN is not needed any more.
> >
> > Can you please describe a bit more detailed why this warning
> > can't trigger anymore?
>
> No, this warning is triggered while detect a duplicate entry in the policy list
>
> regardless of the priority. If we insert policy like this:
>
> policy A (mark.v = 3475289, mark.m = 0, priority = 1) //A is inserted
> policy B (mark.v = 0, mark.m = 0, priority = 0) //B is inserted
> policy C (mark.v = 3475289, mark.m = 0, priority = 0) //C is inserted and B is deleted
The codepath that replaces a policy by another should just trigger
on policy updates (XFRM_MSG_UPDPOLICY). Is that the case in your
test?
It should not be possible to add policy C with XFRM_MSG_NEWPOLICY
as long as you have policy B inserted.
The update replaces an old policy by a new one, the lookup keys of
the old policy must match the lookup keys of the new one. But policy
B has not the same lookup keys as C, the mark is different. So B should
not be replaced with C.
> policy D (mark.v = 3475289, mark.m = 0, priority = 1)
>
> while finding delpol in xfrm_policy_insert_list,
> first round delpol is matched C, whose priority is less than D, so contiue the loop,
> then A is matched， WARN_ON is triggered. It seems the WARN is useless.
Looks like the warning is usefull, it found a bug.
next prev parent reply other threads:[~2020-04-06 9:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-27 12:34 [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting YueHaibing
2020-03-28 11:23 ` Steffen Klassert
2020-03-30 14:05 ` Yuehaibing
2020-04-06 9:03 ` Steffen Klassert [this message]
2020-04-09 8:19 ` Yuehaibing
2020-04-15 7:14 ` Steffen Klassert
2020-04-17 11:01 ` Yuehaibing
2020-04-21 6:28 ` Steffen Klassert
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