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McKenney" , Sasha Levin Subject: [PATCH AUTOSEL for 4.4 008/162] rcu: Make synchronize_rcu_mult() check for duplicates Thread-Topic: [PATCH AUTOSEL for 4.4 008/162] rcu: Make synchronize_rcu_mult() check for duplicates Thread-Index: AQHTz5mWDzgG3nSpl0uHhynD/HCkPA== Date: Mon, 9 Apr 2018 00:27:48 +0000 Message-ID: <20180409002738.163941-8-alexander.levin@microsoft.com> References: <20180409002738.163941-1-alexander.levin@microsoft.com> In-Reply-To: <20180409002738.163941-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1013;7:AngtjdLtZXL1XeO3PdhD8KgZfwCJ3fJvSHd9KQjGcej0ETw0biv+jWOi/oSk5WshNBS+dihmIwRBdSlLvFQQ+ktBbpl7w+waompdl52psnsjzWThCwJeB4IKiz/QIA1pKpSQS+FB6WUwrzsEDByjOWC8+y4QatCvp7WKFtNij/vuKZTQ5rnj50jV+h023MbrP6adHwv/kww2V+sq1LtzqmIjUVNUoSmHTABKi58Laa8qMNpi4745dzwHBJ4Scts8;20:SExEELf3hpP97MdxQttdNsVuBEYtfP1MRFwhwdU1UkQEcOyyZdJNoUc/hgWABnsGfn9zfNXyWWoSPs5dHz2eUfkwWg1QP3gTYtC04ar/xNI9tgScTMhaMOYlvxdt4H6Nn2Y0Yampzu5OMglbnc+Wv2L6YUFUQqcIGj3mzeOjWWc= X-MS-Office365-Filtering-Correlation-Id: 7b921443-7a19-448b-7774-08d59db1b6ce x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(4627221)(201703031133081)(201702281549075)(5600026)(4604075)(3008032)(48565401081)(2017052603328)(7193020);SRVR:DM5PR2101MB1013; x-ms-traffictypediagnostic: DM5PR2101MB1013: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Alexander.Levin@microsoft.com; x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(28532068793085)(89211679590171)(104084551191319); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(61425038)(6040522)(2401047)(8121501046)(5005006)(3231221)(944501327)(52105095)(3002001)(93006095)(93001095)(10201501046)(6055026)(61426038)(61427038)(6041310)(20161123560045)(20161123564045)(20161123558120)(20161123562045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(6072148)(201708071742011);SRVR:DM5PR2101MB1013;BCL:0;PCL:0;RULEID:;SRVR:DM5PR2101MB1013; x-forefront-prvs: 0637FCE711 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39380400002)(39860400002)(396003)(346002)(366004)(376002)(189003)(199004)(478600001)(10290500003)(6436002)(5250100002)(2501003)(14454004)(305945005)(4326008)(66066001)(99286004)(10090500001)(6506007)(36756003)(102836004)(54906003)(486006)(107886003)(76176011)(59450400001)(2900100001)(22452003)(316002)(110136005)(575784001)(86362001)(3660700001)(2906002)(81166006)(186003)(86612001)(81156014)(2616005)(8936002)(3280700002)(11346002)(53936002)(7736002)(476003)(446003)(72206003)(68736007)(6116002)(5660300001)(106356001)(6666003)(6486002)(8676002)(1076002)(105586002)(26005)(6512007)(3846002)(97736004)(25786009)(22906009)(217873001);DIR:OUT;SFP:1102;SCL:1;SRVR:DM5PR2101MB1013;H:DM5PR2101MB1032.namprd21.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; x-microsoft-antispam-message-info: ngD9JDU7aAjLjNZ5LBIvsIzjXsh6uUcD90OlIPAMBBnpDDipVK57rf9bX+9S9O2R38vTUshwj6Yllfm7PERzScq694+QYtilaLitRjWxo2FKquM5C1IPNLV4JWVuwWYeRTVkTATcYBglqBKyWzT05cQqpRRneZ5oCEvucyHjDas3oURxjBKYDKbw7n6OI4fL30OnP8AUDucchtraLdZJlYN+C/rdmJPo+dt9KajKM6N0oSRT5RWkxMoJvod3MfQcHysZ9ybk/FnlPawzpbOhm/BdfLwmZnLXJ6B0OmlfNJmwOubdFISCCyrJ2H/LxEaYnxqQSus5AnNmH379UcQ1qXqrOd8jgOiNMcXJ9eKL6O6fpEFcOSNuh31VFo4MXIsn57nxgYo8FMFBPXw0SeG2jbutVPFQeZO3LgwId7Losow= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7b921443-7a19-448b-7774-08d59db1b6ce X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Apr 2018 00:27:48.7859 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1013 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: "Paul E. McKenney" [ Upstream commit 68ab0b4263224157f4d0c0e42854169a183d7534 ] Currently, doing synchronize_rcu_mult(call_rcu, call_rcu) might (or might not) wait for two RCU grace periods. One approach is of course "don't do that!", but in CONFIG_PREEMPT=3Dn kernels, synchronize_rcu_mult(call_rcu, call_rcu_sched) does exactly that. This results in an ugly #ifdef in sched_cpu_deactivate(). This commit therefore makes __wait_rcu_gp() check for duplicates, which in turn allows duplicates to be passed to synchronize_rcu_mult() without risk of waiting twice on the same type of grace period. Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- kernel/rcu/update.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 5f748c5a40f0..d98acb903325 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -324,6 +324,7 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func= _t *crcu_array, struct rcu_synchronize *rs_array) { int i; + int j; =20 /* Initialize and register callbacks for each flavor specified. */ for (i =3D 0; i < n; i++) { @@ -335,7 +336,11 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_fun= c_t *crcu_array, } init_rcu_head_on_stack(&rs_array[i].head); init_completion(&rs_array[i].completion); - (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); + for (j =3D 0; j < i; j++) + if (crcu_array[j] =3D=3D crcu_array[i]) + break; + if (j =3D=3D i) + (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); } =20 /* Wait for all callbacks to be invoked. */ @@ -344,7 +349,11 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_fun= c_t *crcu_array, (crcu_array[i] =3D=3D call_rcu || crcu_array[i] =3D=3D call_rcu_bh)) continue; - wait_for_completion(&rs_array[i].completion); + for (j =3D 0; j < i; j++) + if (crcu_array[j] =3D=3D crcu_array[i]) + break; + if (j =3D=3D i) + wait_for_completion(&rs_array[i].completion); destroy_rcu_head_on_stack(&rs_array[i].head); } } --=20 2.15.1