From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from EUR01-DB5-obe.outbound.protection.outlook.com (mail-eopbgr60042.outbound.protection.outlook.com [40.107.6.42]) by dpdk.org (Postfix) with ESMTP id 404C21B2B9 for ; Thu, 18 Jan 2018 15:00:24 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Mellanox.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=G9vAI1mojSdztCVUSH5Pp21wfhc77M8nNnF9Qk/DtqE=; b=KrTIvuql1p8ruI7OHk82Bv4EMuCOV3YLy0pIAVN28Oh596sCiTw7NqbTTvbDE0c/3+MR195yyMDn8JvUYLuZCKCzcunmymfyDvtxb9BPpe7meGqrNyFvsg9Pu8Co3N5dWrhMUKzGVxwFLZPhZW0RBCzPmHVJilcO5Wjhh/K/X3M= Received: from AM6PR0502MB3797.eurprd05.prod.outlook.com (52.133.21.26) by AM6PR0502MB4007.eurprd05.prod.outlook.com (52.133.30.142) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id 15.20.428.17; Thu, 18 Jan 2018 14:00:23 +0000 Received: from AM6PR0502MB3797.eurprd05.prod.outlook.com ([fe80::6c28:c6b3:de94:a733]) by AM6PR0502MB3797.eurprd05.prod.outlook.com ([fe80::6c28:c6b3:de94:a733%13]) with mapi id 15.20.0428.014; Thu, 18 Jan 2018 14:00:23 +0000 From: Matan Azrad To: Neil Horman , "Ananyev, Konstantin" CC: Thomas Monjalon , Gaetan Rivet , "Wu, Jingjing" , "dev@dpdk.org" , "Richardson, Bruce" Thread-Topic: [PATCH v2 2/6] ethdev: add port ownership Thread-Index: AQHTihf/M9xg8LYorUSRFqZtTc27hqNtNdVQgAFomACAAAOCwIAAuwQAgABvY+CABQwJgIAAEk3ggABinoCAANUIAIAAxQGAgAAGCnCAAQnKAIAAAmNwgAApSwCAADKGAIABUdOAgAAMD/A= Date: Thu, 18 Jan 2018 14:00:23 +0000 Message-ID: References: <2601191342CEEE43887BDE71AB9772588627DC25@irsmsx105.ger.corp.intel.com> <2601191342CEEE43887BDE71AB9772588627DE30@irsmsx105.ger.corp.intel.com> <2601191342CEEE43887BDE71AB9772588627E954@irsmsx105.ger.corp.intel.com> <2601191342CEEE43887BDE71AB9772588627EE60@irsmsx105.ger.corp.intel.com> <20180117140020.GA5432@hmswarspite.think-freely.org> <2601191342CEEE43887BDE71AB9772588627F0E9@irsmsx105.ger.corp.intel.com> <20180118131017.GA1622@hmswarspite.think-freely.org> In-Reply-To: <20180118131017.GA1622@hmswarspite.think-freely.org> Accept-Language: en-US, he-IL Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=matan@mellanox.com; x-originating-ip: [193.47.165.251] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1; AM6PR0502MB4007; 7:2QUpfos/L8e5lUm4YMFhkFuCaaW966CLpLDQ6vbpcIcgzhE4QS+qVjo3iALfgOwn5BGCtaSneBurzz58uqIUBrWmhOJ9i3/T+A7OUgRUPvBMQSGgcNtCLS1rFLD9h2Mns+qya3zOuBTohq+hIypsqUR0bRgHMI99OBk94iIvyxGVtS6DfrQbk5i6kIuwf2MgIL+ri9meRe+dASwSrTPOoJDMLB3/iOfe0DauVvPg6nun6DO2uUBhZWXi6M4YYqCK x-ms-exchange-antispam-srfa-diagnostics: SSOS; x-ms-office365-filtering-correlation-id: 17983eb6-e492-4309-711a-08d55e7bd184 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:; BCL:0; PCL:0; RULEID:(7020095)(4652020)(5600026)(4604075)(3008032)(48565401081)(2017052603307)(7153060)(7193020); SRVR:AM6PR0502MB4007; x-ms-traffictypediagnostic: AM6PR0502MB4007: x-ld-processed: a652971c-7d2e-4d9b-a6a4-d149256f461b,ExtAddr x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(60795455431006)(228905959029699); x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(6040470)(2401047)(8121501046)(5005006)(3231023)(2400062)(944501161)(10201501046)(93006095)(93001095)(3002001)(6055026)(6041268)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123564045)(20161123562045)(20161123560045)(20161123558120)(6072148)(201708071742011); SRVR:AM6PR0502MB4007; BCL:0; PCL:0; RULEID:(100000803101)(100110400095); SRVR:AM6PR0502MB4007; x-forefront-prvs: 05568D1FF7 x-forefront-antispam-report: SFV:NSPM; SFS:(10009020)(39860400002)(39380400002)(346002)(376002)(396003)(366004)(199004)(189003)(51444003)(13464003)(81156014)(2906002)(8676002)(81166006)(102836004)(14454004)(7736002)(2900100001)(86362001)(6116002)(305945005)(105586002)(33656002)(3846002)(26005)(229853002)(6436002)(55016002)(9686003)(3660700001)(53936002)(8936002)(97736004)(5250100002)(478600001)(93886005)(4326008)(316002)(110136005)(25786009)(99286004)(74316002)(3280700002)(6246003)(68736007)(54906003)(53546011)(66066001)(76176011)(59450400001)(7696005)(5660300001)(2950100002)(106356001)(6506007); DIR:OUT; SFP:1101; SCL:1; SRVR:AM6PR0502MB4007; H:AM6PR0502MB3797.eurprd05.prod.outlook.com; FPR:; SPF:None; PTR:InfoNoRecords; A:1; MX:1; LANG:en; received-spf: None (protection.outlook.com: mellanox.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: Bowp4jyXoQf5hpTD9CbzHGsKycdMyLg7PFkiTGwF7zNiRMgqwLPpOvdtYPVHIx199EoEQspq08zEn/I5m9i/bg== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: 17983eb6-e492-4309-711a-08d55e7bd184 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 Jan 2018 14:00:23.0649 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM6PR0502MB4007 Subject: Re: [dpdk-dev] [PATCH v2 2/6] ethdev: add port ownership X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Jan 2018 14:00:25 -0000 Hi Neil From: Neil Horman, Thursday, January 18, 2018 3:10 PM > On Wed, Jan 17, 2018 at 05:01:10PM +0000, Ananyev, Konstantin wrote: > > > > > > > -----Original Message----- > > > From: Neil Horman [mailto:nhorman@tuxdriver.com] > > > Sent: Wednesday, January 17, 2018 2:00 PM > > > To: Matan Azrad > > > Cc: Ananyev, Konstantin ; Thomas > > > Monjalon ; Gaetan Rivet > > > ; Wu, Jingjing ; > > > dev@dpdk.org; Richardson, Bruce > > > Subject: Re: [PATCH v2 2/6] ethdev: add port ownership > > > > > > On Wed, Jan 17, 2018 at 12:05:42PM +0000, Matan Azrad wrote: > > > > > > > > Hi Konstantin > > > > From: Ananyev, Konstantin, Sent: Wednesday, January 17, 2018 1:24 > > > > PM > > > > > Hi Matan, > > > > > > > > > > > Hi Konstantin > > > > > > > > > > > > From: Ananyev, Konstantin, Tuesday, January 16, 2018 9:11 PM > > > > > > > Hi Matan, > > > > > > > > > > > > > > > > > > > > > > > Hi Konstantin > > > > > > > > From: Ananyev, Konstantin, Monday, January 15, 2018 8:44 > > > > > > > > PM > > > > > > > > > Hi Matan, > > > > > > > > > > Hi Konstantin > > > > > > > > > > From: Ananyev, Konstantin, Monday, January 15, 2018 > > > > > > > > > > 1:45 PM > > > > > > > > > > > Hi Matan, > > > > > > > > > > > > Hi Konstantin > > > > > > > > > > > > From: Ananyev, Konstantin, Friday, January 12, > > > > > > > > > > > > 2018 2:02 AM > > > > > > > > > > > > > Hi Matan, > > > > > > > > > > > > > > Hi Konstantin > > > > > > > > > > > > > > From: Ananyev, Konstantin, Thursday, January > > > > > > > > > > > > > > 11, 2018 > > > > > > > > > > > > > > 2:40 PM > > > > > > > > > > > > > > > Hi Matan, > > > > > > > > > > > > > > > > Hi Konstantin > > > > > > > > > > > > > > > > From: Ananyev, Konstantin, Wednesday, > > > > > > > > > > > > > > > > January 10, > > > > > > > > > > > > > > > > 2018 > > > > > > > > > > > > > > > > 3:36 PM > > > > > > > > > > > > > > > > > Hi Matan, > > > > > > > > > > > > > > > > > > > > > > > > > It is good to see that now > > > > > > > > > > > > > > > > > scanning/updating rte_eth_dev_data[] is > > > > > > > > > > > > > > > > > lock protected, but it might be not very > > > > > > > > > > > > > > > > > plausible to protect both data[] and > > > > > > > > > > > > > > > > > next_owner_id using the > > > > > > > > > > > same lock. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I guess you mean to the owner structure in > > > > > > > > > > > rte_eth_dev_data[port_id]. > > > > > > > > > > > > > > > > The next_owner_id is read by ownership > > > > > > > > > > > > > > > > APIs(for owner validation), so it > > > > > > > > > > > > > > > makes sense to use the same lock. > > > > > > > > > > > > > > > > Actually, why not? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Well to me next_owner_id and > > > > > > > > > > > > > > > rte_eth_dev_data[] are not directly > > > > > > > > > > > > > related. > > > > > > > > > > > > > > > You may create new owner_id but it doesn't > > > > > > > > > > > > > > > mean you would update rte_eth_dev_data[] > immediately. > > > > > > > > > > > > > > > And visa-versa - you might just want to > > > > > > > > > > > > > > > update rte_eth_dev_data[].name or .owner_id. > > > > > > > > > > > > > > > It is not very good coding practice to use > > > > > > > > > > > > > > > same lock for non-related data structures. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I see the relation like next: > > > > > > > > > > > > > > Since the ownership mechanism synchronization > > > > > > > > > > > > > > is in ethdev responsibility, we must protect > > > > > > > > > > > > > > against user mistakes as much as we can by > > > > > > > > > > > > > using the same lock. > > > > > > > > > > > > > > So, if user try to set by invalid owner > > > > > > > > > > > > > > (exactly the ID which currently is > > > > > > > > > > > > > allocated) we can protect on it. > > > > > > > > > > > > > > > > > > > > > > > > > > Hmm, not sure why you can't do same checking > > > > > > > > > > > > > with different lock or atomic variable? > > > > > > > > > > > > > > > > > > > > > > > > > The set ownership API is protected by ownership > > > > > > > > > > > > lock and checks the owner ID validity By reading th= e next > owner ID. > > > > > > > > > > > > So, the owner ID allocation and set API should use > > > > > > > > > > > > the same atomic > > > > > > > > > > > mechanism. > > > > > > > > > > > > > > > > > > > > > > Sure but all you are doing for checking validity, is > > > > > > > > > > > check that owner_id > 0 &&& owner_id < next_ownwe_id, > right? > > > > > > > > > > > As you don't allow owner_id overlap (16/3248 bits) > > > > > > > > > > > you can safely do same check with just > atomic_get(&next_owner_id). > > > > > > > > > > > > > > > > > > > > > It will not protect it, scenario: > > > > > > > > > > - current next_id is X. > > > > > > > > > > - call set ownership of port A with owner id X by > > > > > > > > > > thread 0(by user > > > > > > > mistake). > > > > > > > > > > - context switch > > > > > > > > > > - allocate new id by thread 1 and get X and change > > > > > > > > > > next_id to > > > > > > > > > > X+1 > > > > > > > > > atomically. > > > > > > > > > > - context switch > > > > > > > > > > - Thread 0 validate X by atomic_read and succeed to > > > > > > > > > > take > > > > > ownership. > > > > > > > > > > - The system loosed the port(or will be managed by two > > > > > > > > > > entities) - > > > > > > > crash. > > > > > > > > > > > > > > > > > > > > > > > > > > > Ok, and how using lock will protect you with such scenari= o? > > > > > > > > > > > > > > > > The owner set API validation by thread 0 should fail > > > > > > > > because the owner > > > > > > > validation is included in the protected section. > > > > > > > > > > > > > > Then your validation function would fail even if you'll use > > > > > > > atomic ops instead of lock. > > > > > > No. > > > > > > With atomic this specific scenario will cause the validation to= pass. > > > > > > > > > > Can you explain to me how? > > > > > > > > > > rte_eth_is_valid_owner_id(uint16_t owner_id) { > > > > > int32_t cur_owner_id =3D > > > > > RTE_MIN(rte_atomic32_get(next_owner_id), > > > > > UINT16_MAX); > > > > > > > > > > if (owner_id =3D=3D RTE_ETH_DEV_NO_OWNER || owner > > > > > > cur_owner_id) { > > > > > RTE_LOG(ERR, EAL, "Invalid owner_id=3D%d.\n", owner_id); > > > > > return 0; > > > > > } > > > > > return 1; > > > > > } > > > > > > > > > > Let say your next_owne_id=3D=3DX, and you invoke > > > > > rte_eth_is_valid_owner_id(owner_id=3DX+1) - it would fail. > > > > > > > > Explanation: > > > > The scenario with locks: > > > > next_owner_id =3D X. > > > > Thread 0 call to set API(with invalid owner Y=3DX) and take lock. > > > > Context switch. > > > > Thread 1 call to owner_new and stuck in the lock. > > > > Context switch. > > > > Thread 0 does owner id validation and failed(Y>=3DX) - unlock the l= ock and > return failure to the user. > > > > Context switch. > > > > Thread 1 take the lock and update X to X+1, then, unlock the lock. > > > > Everything is OK! > > > > > > > > The same scenario with atomics: > > > > next_owner_id =3D X. > > > > Thread 0 call to set API(with invalid owner Y=3DX) and take lock. > > > > Context switch. > > > > Thread 1 call to owner_new and change X to X+1(atomically). > > > > Context switch. > > > > Thread 0 does owner id validation and success(Y<(atomic)X+1) - unlo= ck > the lock and return success to the user. > > > > Problem! > > > > > > > > > > > > > Matan is correct here, there is no way to preform parallel set > > > operations using just and atomic variable here, because multiple > > > reads of next_owner_id need to be preformed while it is stable. > > > That is to say rte_eth_next_owner_id must be compared to > > > RTE_ETH_DEV_NO_OWNER and owner_id in rte_eth_is_valid_owner_id. > If > > > you were to only use an atomic_read on such a variable, it could be > > > incremented by the owner_new function between the checks and an > > > invalid owner value could become valid because a third thread > > > incremented the next value. The state of next_owner_id must be kept > > > stable during any validity checks > > > > It could still be incremented between the checks - if let say > > different thread will invoke new_onwer_id, grab the lock update > > counter, release the lock - all that before the check. > I don't see how all of the contents of rte_eth_dev_owner_set is protected > under rte_eth_dev_ownership_lock, as is rte_eth_dev_owner_new. > Next_owner might increment between another threads calls to owner_new > and owner_set, but that will just cause a transition from an ownership id > being valid to invalid, and thats ok, as long as there is consistency in = the > model that enforces a single valid owner at a time (in that case the > subsequent caller to owner_new). >=20 I'm not sure I fully understand you, but see: we can't protect all of the user mistakes(using the wrong owner id). But we are doing the maximum for it. > Though this confusion does underscore my assertion I think that this API = is > overly complicated >=20 I really don't think it is complicated. - just take ownership of a port(by = owner id allocation and set APIs) and manage the port as you want.=20 > Neil