From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Leonard Crestez To: "sboyd@codeaurora.org" CC: "linux-kernel@vger.kernel.org" , "mturquette@baylibre.com" , "linux-clk@vger.kernel.org" Subject: Re: [PATCH] clk: core: Copy connection id Date: Thu, 2 Mar 2017 12:45:16 +0000 Message-ID: <1488458715.12287.18.camel@nxp.com> References: <60d115f6c11bc51cd8bc10c64cd222c3cdb43cc7.1487596492.git.leonard.crestez@nxp.com> <20170224204439.GD25384@codeaurora.org> <1488014402.6461.3.camel@nxp.com> <20170228080558.GL25384@codeaurora.org> In-Reply-To: <20170228080558.GL25384@codeaurora.org> Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 List-ID: T24gVHVlLCAyMDE3LTAyLTI4IGF0IDAwOjA1IC0wODAwLCBzYm95ZEBjb2RlYXVyb3JhLm9yZyB3 cm90ZToNCj4gT24gMDIvMjUsIExlb25hcmQgQ3Jlc3RleiB3cm90ZToNCj4gPiANCj4gPiBPbiBG cmksIDIwMTctMDItMjQgYXQgMTI6NDQgLTA4MDAsIFN0ZXBoZW4gQm95ZCB3cm90ZToNCj4gPiA+ IA0KPiA+ID4gT24gMDIvMjAsIExlb25hcmQgQ3Jlc3RleiB3cm90ZToNCj4gPiA+ID4gDQo+ID4g PiA+IFNvbWUgZHJpdmVycyB1c2Ugc3ByaW50ZiB0byBidWlsZCBjbGsgY29ubmVjdGlvbiBpZCBu YW1lcyBidXQNCj4gPiA+ID4gdGhlDQo+ID4gPiA+IGNsaw0KPiA+ID4gPiBjb3JlIHdpbGwgc2F2 ZSB0aG9zZSBzdHJpbmdzIGFuZCBvY2Nhc2lvbmFsbHkgcHJpbnQgdGhlbSBiYWNrLg0KPiA+ID4g PiBEdXBsaWNhdGUNCj4gPiA+ID4gdGhlIGNvbl9pZCBzdHJpbmdzIGluc3RlYWQgb2YgZml4aW5n IGFsbCB0aGUgdXNlcnMuDQo+ID4gPiBHb29kIGNhdGNoLiBXaGF0IGFib3V0IGRldl9pZCB0aG91 Z2g/IFRoYXQgY291bGQgYWxzbyBoYXZlIHRoZQ0KPiA+ID4gc2FtZSBwcm9ibGVtIGlmIHNvbWUg ZGV2aWNlIGlzIHJlbW92ZWQgYW5kIHdlJ3JlIHN0aWxsIGhvbGRpbmcgYQ0KPiA+ID4gcmVmZXJl bmNlIHRvIHRoZSBrb2JqZWN0J3MgbmFtZS4gVGhpcyBpcyBwcm9iYWJseSBtb3JlIHJhcmUgdGhh bg0KPiA+ID4gd2hhdCBpcyBoYXBwZW5pbmcgaGVyZSwgYnV0IHN0aWxsIHNlZW1zIHBvc3NpYmxl IHRoYXQgd2UgbWlnaHQNCj4gPiA+IHRyaXAgb3ZlciB0aGF0IGxhdGVyLg0KPiA+IEEgZGV2aWNl IHNob3VsZCBub3JtYWxseSBmcmVlIHRoZSBjbGtzIGl0IHVzZXMgYmVmb3JlIGl0IGlzDQo+ID4g ZGVzdHJveWVkLg0KPiA+IFRoaXMgbWVhbnMgdGhhdCBpZiBkZXZfaWQgaXMgcG9pbnRpbmcgdG8g ZnJlZWQgbWVtb3J5IHRoZW4gdGhlIGNsaw0KPiA+IGl0c2VsZiB3YXMgcHJvYmFibHkgbGVha2Vk LCByaWdodD8NCj4gU3VyZS4gY2xrX2dldF9zeXMoKSBjb3VsZCBiZSBjYWxsZWQgYW5kIHRoZW4g d2UgY291bGQgaGF2ZQ0KPiBzb21ldGhpbmcgc3ByaW50ZiB0aGUgZGV2X2lkIHRoZXJlLiBBIHF1 aWNrIGdyZXAgZG9lc24ndCBzaG93IGFueQ0KPiBwbGFjZSB3aGVyZSB0aGF0IGhhcHBlbnMgdGhv dWdoIHNvIGl0IHNlZW1zIHNhZmUgcmlnaHQgbm93Lg0KPiANCj4gVGhhdCBzYWlkLCBpdCB3b3Vs ZCBiZSBuaWNlIHRvIGNsZWFybHkgZG9jdW1lbnQgdGhhdCB3ZSBkb24ndA0KPiBleHBlY3QgZGV2 X2lkIHRvIGJlIGZyZWVkIG9yIGNoYW5nZWQgZHVyaW5nIHRoZSBsaWZldGltZSBvZiB0aGUNCj4g Y2xrIHN0cnVjdHVyZSwgYnV0IHdlIGRvIGFsbG93IGNvbl9pZCB0byBjaGFuZ2UuIFBlcmhhcHMg dGhlIGNvcHkNCj4gc2hvd3MgdGhhdCwgYnV0IGEgY29tbWVudCB3b3VsZCBhbHNvIGJlIHVzZWZ1 bCBzbyB3ZSBkb24ndCBoYXZlDQo+IHBlb3BsZSB3b25kZXJpbmcgd2h5IGRldl9pZCBpc24ndCBj b3BpZWQgYXMgd2VsbC4NCg0KVGhpcyBzaG91bGQgYmUgbWVudGlvbmVkIG9uIHRoZSBwdWJsaWMg ZG9jdW1lbnRhdGlvbiBmb3IgY2xrX2dldF9zeXMsDQpjbGtfZ2V0IGFuZCBkZXZtX2Nsa19nZXQs IHJpZ2h0PyBUaGVzZSBzZWVtIHRvIGJlIHRoZSBwdWJsaWMgZW50cnkNCnBvaW50cyB0byB0aGUg Y2xrIHN1YnN5c3RlbSBhbmQgdXNlcnMgYXJlIGV4cGVjdGVkIHRvIHJlYWQgdGhlaXIgZG9jcy4N Cg0KRG8geW91IHdhbnQgbWUgdG8gcmVzZW5kIHRoZSBwYXRjaCB3aXRoIHRoZXNlIG5vdGVzPw0K DQpJJ20gbm90IGNvbWZvcnRhYmxlIGFkZGluZyB0byBkb2N1bWVudGF0aW9uIHdoZW4gSSBkb24n dCBmdWxseQ0KdW5kZXJzdGFuZCB0aGUgc3lzdGVtIG15c2VsZi4gSSBvbmx5IGRpc2NvdmVyZWQg dGhpcyB3aGlsZSBsb29raW5nIGludG8NCnVucmVsYXRlZCBkcml2ZXIgaXNzdWVzLg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754724AbdCBR1I (ORCPT ); Thu, 2 Mar 2017 12:27:08 -0500 Received: from mail-db5eur01on0078.outbound.protection.outlook.com ([104.47.2.78]:43008 "EHLO EUR01-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750841AbdCBR0O (ORCPT ); Thu, 2 Mar 2017 12:26:14 -0500 From: Leonard Crestez To: "sboyd@codeaurora.org" CC: "linux-kernel@vger.kernel.org" , "mturquette@baylibre.com" , "linux-clk@vger.kernel.org" Subject: Re: [PATCH] clk: core: Copy connection id Thread-Topic: [PATCH] clk: core: Copy connection id Thread-Index: AQHSi3wypNDeVI6X5k2xubw35qCiQKF4pqmAgADTDgCABKJMAIADcrKA Date: Thu, 2 Mar 2017 12:45:16 +0000 Message-ID: <1488458715.12287.18.camel@nxp.com> References: <60d115f6c11bc51cd8bc10c64cd222c3cdb43cc7.1487596492.git.leonard.crestez@nxp.com> <20170224204439.GD25384@codeaurora.org> <1488014402.6461.3.camel@nxp.com> <20170228080558.GL25384@codeaurora.org> In-Reply-To: <20170228080558.GL25384@codeaurora.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: codeaurora.org; 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x-forefront-prvs: 023495660C x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(6009001)(7916002)(39410400002)(39850400002)(39840400002)(39450400003)(39860400002)(377424004)(24454002)(3280700002)(122556002)(3660700001)(6512007)(2906002)(92566002)(2950100002)(54906002)(7736002)(103116003)(6506006)(2351001)(2900100001)(2501003)(99286003)(305945005)(53936002)(66066001)(6436002)(36756003)(229853002)(6486002)(25786008)(77096006)(106116001)(76176999)(5660300001)(54356999)(110136004)(1730700003)(8676002)(38730400002)(33646002)(8936002)(5640700003)(6916009)(81166006)(6246003)(102836003)(4326008)(50986999)(189998001)(93886004)(3846002)(6116002)(86362001);DIR:OUT;SFP:1101;SCL:1;SRVR:AM5PR04MB3218;H:AM5PR04MB3219.eurprd04.prod.outlook.com;FPR:;SPF:None;MLV:sfv;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: <49BA70200CC3744A9540D7BF4E7B5C03@eurprd04.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Mar 2017 12:45:16.2702 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM5PR04MB3218 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id v22HS8UO017785 On Tue, 2017-02-28 at 00:05 -0800, sboyd@codeaurora.org wrote: > On 02/25, Leonard Crestez wrote: > > > > On Fri, 2017-02-24 at 12:44 -0800, Stephen Boyd wrote: > > > > > > On 02/20, Leonard Crestez wrote: > > > > > > > > Some drivers use sprintf to build clk connection id names but > > > > the > > > > clk > > > > core will save those strings and occasionally print them back. > > > > Duplicate > > > > the con_id strings instead of fixing all the users. > > > Good catch. What about dev_id though? That could also have the > > > same problem if some device is removed and we're still holding a > > > reference to the kobject's name. This is probably more rare than > > > what is happening here, but still seems possible that we might > > > trip over that later. > > A device should normally free the clks it uses before it is > > destroyed. > > This means that if dev_id is pointing to freed memory then the clk > > itself was probably leaked, right? > Sure. clk_get_sys() could be called and then we could have > something sprintf the dev_id there. A quick grep doesn't show any > place where that happens though so it seems safe right now. > > That said, it would be nice to clearly document that we don't > expect dev_id to be freed or changed during the lifetime of the > clk structure, but we do allow con_id to change. Perhaps the copy > shows that, but a comment would also be useful so we don't have > people wondering why dev_id isn't copied as well. This should be mentioned on the public documentation for clk_get_sys, clk_get and devm_clk_get, right? These seem to be the public entry points to the clk subsystem and users are expected to read their docs. Do you want me to resend the patch with these notes? I'm not comfortable adding to documentation when I don't fully understand the system myself. I only discovered this while looking into unrelated driver issues.