linux-kernel - Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

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Date:   Mon, 30 Mar 2020 22:05:32 +0800
From:   Yuehaibing <yuehaibing@...wei.com>
To:     Steffen Klassert <steffen.klassert@...unet.com>
CC:     <herbert@...dor.apana.org.au>, <davem@...emloft.net>,
        <kuba@...nel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm
 policy inserting

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
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.

> 
> Thanks!
> 
>