Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::3:5 as permitted sender) client-ip=2620:137:e000::3:5;
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] lockd: hold a reference to nlmsvc_serv while stopping
 thread.
Thread-Topic: [PATCH] lockd: hold a reference to nlmsvc_serv while stopping
 thread.
Thread-Index: AQHZ+wlZQQI+ju6EmkWAayUDxKVMCbBC93oAgAClFgCAAO3pgA==
Date:   Wed, 11 Oct 2023 12:41:48 +0000
Message-ID: <39CD2E44-0905-40DC-A75B-64B689791562@oracle.com>
References: <169689454310.26263.15848180396022999880@noble.neil.brown.name>
 <834A724C-4A44-4277-AFB5-D639FCF2900B@oracle.com>
 <169697700659.26263.12600384009390271074@noble.neil.brown.name>
In-Reply-To: <169697700659.26263.12600384009390271074@noble.neil.brown.name>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?hTHIxiLE9CcF0PMFk9buylZWEXfMbcCQSyAeCq04UfACm/KKhVaKewlCN7Zl?=
 =?us-ascii?Q?gL7EyJnH4Oxz+XRyV0uQgwDWjyXT9LvMj9jii95fpQYbTAr4NwAiuzEN9boX?=
 =?us-ascii?Q?lcO0s19NvcIZMYxSZ6uk629ArERh06gXg9xznrQkmJb1s6Ftd/NPth4dBGRN?=
 =?us-ascii?Q?bFiYlllxwLJ8PMP/yAQfryschQ69MklFu2Yw/YMQNxofToD7vG2bQRIMAjLB?=
 =?us-ascii?Q?GbYgfhRpNxgJnNyJORrzAWkgMdqB6uDgbZWjxhTm8U4obl+d9DrdkmVpTtS6?=
 =?us-ascii?Q?gvIW0iNSIhj6665WjPVQsyLPguxp5pYVPn8TsW1zFULXuT7R1NX5gblUSabc?=
 =?us-ascii?Q?lkyhGlNHbwA3IGtTFEt4ROIRe+884hl4ATWYwU8AZjcaBjoS6eQhkkLkbAH4?=
 =?us-ascii?Q?W06Z5J+BZ/TOazijs05QlQ4E2h/uPbThNoh76/Gmua0FCAtH/C7X4r2QSj5i?=
 =?us-ascii?Q?DlBcE9QcHPydrFDH0Pzfj3UFmWNH/0rYldBJLeHXAt9r7Dby+tRdbziIl4DP?=
 =?us-ascii?Q?fjJlTJXxEiygH8EcK+78LRVo2kU23DnAAZdpBl8GoyvHyf4S1zQljBoAkhbH?=
 =?us-ascii?Q?FPJt1q+Vj2BXcbFBFzZx+CBkRfTEdToIpMMU74F2+jfUzuvEo594LMYJibal?=
 =?us-ascii?Q?dAGGO0W2OCO2XX4xZ3mJ7Qh91VAfieu7W8m0BZJnCAATBTg0ZJU8MemD9y8t?=
 =?us-ascii?Q?Y8+9GHDL9//2c6lnFjL0/k2Uk2CyiUeuBBEtaV6Mun+DO3Dxxq1iiB49Uy87?=
 =?us-ascii?Q?7pv0NaBvx1esUn4dNhVRSlPON085fbnvYI78ZIam80JTmM+UWdNKX29uhuV5?=
 =?us-ascii?Q?/nNsH03uQ15+QOxyCxBgMeIX2Rxe9OrwTvDNwx8ZexvJIBWK6h/O4CUxXBmw?=
 =?us-ascii?Q?a5BCMq4s8UHKgTno6zk/AKQd+zJ9qIlJ+gzJ7KI/JhToeYxerYgZSdk89TnW?=
 =?us-ascii?Q?mXU3o7LH17tgBWszzSAbvrqTI4i+7Ckmjb5Zw9zIAcp4ShXBwVPMjtdm1iSZ?=
 =?us-ascii?Q?25uqTNDb5eC4X0PpCNlyAlL3O/dxKoHiH6gQtNtMdZm6oPTm5n9P/cZ5PBWi?=
 =?us-ascii?Q?42OoHpWIUEx2FfEgfKbfaPJSzmYA6aATYoP3IGK4RRXV79PgtTBdHrOIUE/b?=
 =?us-ascii?Q?y3jCvdsryOnNxDxcWu5tgtmo//uJc5bsFaGIpDDjWcNeagWYDqRZbsvyOboU?=
 =?us-ascii?Q?TWpUH+Dw+jUcsLOeP77Wud/2Xp9SR9GpyFXYxo0jvGKK357OWUuy9MZprJLp?=
 =?us-ascii?Q?E5C7KiL8cSVVPmYdgL0ZeuMiFhzC4j3iyzVb7SB3xB4iFHW5MUlAfMb9+QjI?=
 =?us-ascii?Q?601N1ijHYarT1STtACD01GObg4jnHWu0W5QvQ9Yp+MyJrmXBEGFsow6ePbYZ?=
 =?us-ascii?Q?WjClfrZRpe8MwGiT6hSyEJEKh6CWRT8IJMY0VCSbtDPDhbexZS6S3XSrUp6G?=
 =?us-ascii?Q?eifoTbv91toTpHxGHuUmmxJEh3hc7eKROR4B7O2SassLlsIAFd1EUntqPcBc?=
 =?us-ascii?Q?aD6XPPzlXdqQKwXdtRJhf9eLceSU/Fh/Is5pvR8D3Skij7xYgc3ZNKdcH0Vc?=
 =?us-ascii?Q?Cu/tiLTbo47sQlQHJ9A14PB9AciaT17vOTaGjK+YnQ5ezrO/yCaPr34MY7er?=
 =?us-ascii?Q?9w=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <009ABCB84DC9B944A42B47361CD3BBDB@namprd10.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: BN0PR10MB5128.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 52226826-3ab3-450f-1308-08dbca576fc6
X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Oct 2023 12:41:48.9011
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: eq5KIhFKVXKSh43PC8+XmYRBQEwsy2AWhHViVHpRktb2GBIBwsrW2UzHFONuwELRrEpkt9FrZjcxsJfM7D7AXA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW6PR10MB7592
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26
 definitions=2023-10-11_09,2023-10-11_01,2023-05-22_02
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 adultscore=0
 suspectscore=0 mlxlogscore=999 phishscore=0 bulkscore=0 malwarescore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2309180000
 definitions=main-2310110111
X-Proofpoint-ORIG-GUID: Syz5-UvNMreRo2p2WXhXZqLGRSXUqh-q
X-Proofpoint-GUID: Syz5-UvNMreRo2p2WXhXZqLGRSXUqh-q
X-Spam-Status: No, score=2.7 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
	DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,
	RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no
	version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on groat.vger.email
Precedence: bulk
List-ID: <linux-nfs.vger.kernel.org>
X-Mailing-List: linux-nfs@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (groat.vger.email [0.0.0.0]); Wed, 11 Oct 2023 05:42:17 -0700 (PDT)
X-Spam-Level: **


> On Oct 10, 2023, at 6:30 PM, NeilBrown <neilb@suse.de> wrote:
>=20
> On Tue, 10 Oct 2023, Chuck Lever III wrote:
>>=20
>>> On Oct 9, 2023, at 7:35 PM, NeilBrown <neilb@suse.de> wrote:
>>> We are required to hold a reference to the svc_serv struct while
>>> stopping the last thread, as doing that could otherwise drop the last
>>> reference itself and the svc_serv would be freed while still in use.
>>>=20
>>> lockd doesn't do this.  After startup, the only reference is held by th=
e
>>> running thread.
>>>=20
>>> So change locked to hold a reference on nlmsvc_serv while-ever the
>>> service is active, and only drop it after the last thread has been
>>> stopped.
>>>=20
>>> Note: it doesn't really make sense for threads to hold references to th=
e
>>> svc_serv any more.  The fact threads are included in serv->sv_nrthreads
>>> is sufficient.  Maybe a future patch could address this.
>>>=20
>>> Reported-by: Jeff Layton <jlayton@kernel.org>
>>> Fixes: 68cc388c3238 ("SUNRPC: change how svc threads are asked to exit.=
")
>>> Signed-off-by: NeilBrown <neilb@suse.de>
>>=20
>> Thanks for the fast response!
>>=20
>> Should I squash this into 68cc, or apply it before? I would
>> like to ensure that bisect works nicely over this series of
>> commits.
>=20
> Probably makes sense to put it before.  In that case the patch
> description needs re-wording.
>=20
> And on reflection I think the code should be changed a little so that it
> matches similar code in nfsd and nfs4-callback.
> So I'll repost.
> I'll take the liberty of preserving Jeff's review/test even though I've
> changed the code .... I hope that's OK.

Sounds like a plan. I've picked up v2 and applied it to nfsd-next.


--
Chuck Lever