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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Neil Brown <neilb@suse.de>
CC:     Jeff Layton <jlayton@kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Olga Kornievskaia <kolga@netapp.com>,
        Dai Ngo <dai.ngo@oracle.com>, Tom Talpey <tom@talpey.com>
Subject: Re: [PATCH 0/5] sunrpc: not refcounting svc_serv
Thread-Topic: [PATCH 0/5] sunrpc: not refcounting svc_serv
Thread-Index: AQHaCs5Bx30Sst3AQkeWzWCFyIpqgLBkCzaAgABUNQCAAACLgIAAAScAgAAA4YA=
Date:   Tue, 31 Oct 2023 20:50:05 +0000
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> On Oct 31, 2023, at 1:46 PM, NeilBrown <neilb@suse.de> wrote:
>=20
> On Wed, 01 Nov 2023, Chuck Lever III wrote:
>>=20
>>> On Oct 31, 2023, at 1:40 PM, NeilBrown <neilb@suse.de> wrote:
>>>=20
>>> On Wed, 01 Nov 2023, Chuck Lever III wrote:
>>>>=20
>>>>> On Oct 29, 2023, at 6:08 PM, NeilBrown <neilb@suse.de> wrote:
>>>>>=20
>>>>> This patch set continues earlier work of improving how threads and
>>>>> services are managed.  Specifically it drop the refcount.
>>>>>=20
>>>>> The refcount is always changed under the mutex, and almost always is
>>>>> exactly equal to the number of threads.  Those few cases where it is
>>>>> more than the number of threads can usefully be handled other ways as
>>>>> see in the patches.
>>>>>=20
>>>>> The first patches fixes a potential use-after-free when adding a sock=
et
>>>>> fails.  This might be the UAF that Jeff mentioned recently.
>>>>>=20
>>>>> The second patch which removes the use of a refcount in pool_stats
>>>>> handling is more complex than I would have liked, but I think it is
>>>>> worth if for the result seen in 4/5 of substantial simplification.
>>>>=20
>>>> So I need a v2 of this series, then...
>>>>=20
>>>> - Move 4/5 to the beginning of the series (patch 1 or 2, doesn't matte=
r)
>>>=20
>>> I don't understand....  2 and 3 are necessary prerequisites for 4.  The
>>> remove places where the refcount is used.
>>=20
>> Hrm. that's what I was afraid of.
>>=20
>> Isn't there a fix in 4/5 that we want applied to stable kernels,
>> or did I misunderstand the email exchange between you and Jeff?
>>=20
> That is=20
> Commit bf32075256e9 ("NFSD: simplify error paths in nfsd_svc()")
> which is already in nfsd-next.

OK. I'm still confused, but let's just keep the patch ordering
the way it was in v1, then. We'll work out any missing fixes
as they arise.

--
Chuck Lever