Messages in this thread | | | Date | Mon, 6 Apr 2020 11:03:27 +0200 | From | Steffen Klassert <> | Subject | Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting |
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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.
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