From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754830AbdKNKfE (ORCPT ); Tue, 14 Nov 2017 05:35:04 -0500 Received: from mail-eopbgr20050.outbound.protection.outlook.com ([40.107.2.50]:19148 "EHLO EUR02-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754176AbdKNKex (ORCPT ); Tue, 14 Nov 2017 05:34:53 -0500 From: Oleksandr Shamray To: "'Chip Bilbrey'" CC: "gregkh@linuxfoundation.org" , "arnd@arndb.de" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , "openbmc@lists.ozlabs.org" , "joel@jms.id.au" , "jiri@resnulli.us" , "tklauser@distanz.ch" , "linux-serial@vger.kernel.org" , "mec@shout.net" , "robh+dt@kernel.org" , "openocd-devel-owner@lists.sourceforge.net" , "linux-api@vger.kernel.org" , "davem@davemloft.net" , "mchehab@kernel.org" , Jiri Pirko Subject: RE: [v11,1/4] drivers: jtag: Add JTAG core driver Thread-Topic: [v11,1/4] drivers: jtag: Add JTAG core driver Thread-Index: AQHTVoYZEAkiZu03y0GEL/O3ci1kT6MTubmg Date: Tue, 14 Nov 2017 10:34:49 +0000 Message-ID: References: <1509724449-26221-2-git-send-email-oleksandrs@mellanox.com> <8760aoz78q.fsf@bilbrey.org> In-Reply-To: <8760aoz78q.fsf@bilbrey.org> Accept-Language: en-US, uk-UA Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=oleksandrs@mellanox.com; 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x-forefront-prvs: 04916EA04C x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(6009001)(346002)(376002)(39860400002)(189002)(199003)(13464003)(33656002)(53546010)(189998001)(68736007)(66066001)(2906002)(316002)(106356001)(105586002)(5660300001)(478600001)(86362001)(2900100001)(55016002)(7416002)(7696004)(101416001)(5250100002)(14454004)(74316002)(2950100002)(6916009)(6506006)(4326008)(54906003)(3280700002)(6436002)(9686003)(3660700001)(25786009)(81166006)(102836003)(50986999)(99286004)(3846002)(6116002)(81156014)(8936002)(229853002)(54356999)(53936002)(76176999)(6246003)(305945005)(97736004)(107886003)(8676002)(7736002);DIR:OUT;SFP:1101;SCL:1;SRVR:AM4PR05MB1745;H:DB6PR0501MB2197.eurprd05.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: 08132faa-9471-4599-286a-08d52b4b554f X-MS-Exchange-CrossTenant-originalarrivaltime: 14 Nov 2017 10:34:49.5335 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM4PR05MB1745 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 quoted-printable to 8bit by nfs id vAEAZ9OP005038 > -----Original Message----- > From: Chip Bilbrey [mailto:chip@bilbrey.org] > Sent: Monday, November 6, 2017 12:33 AM > To: Oleksandr Shamray > Cc: gregkh@linuxfoundation.org; arnd@arndb.de; linux- > kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; > devicetree@vger.kernel.org; openbmc@lists.ozlabs.org; joel@jms.id.au; > jiri@resnulli.us; tklauser@distanz.ch; linux-serial@vger.kernel.org; > mec@shout.net; Vadim Pasternak ; system-sw-low- > level ; robh+dt@kernel.org; openocd- > devel-owner@lists.sourceforge.net; linux-api@vger.kernel.org; > davem@davemloft.net; mchehab@kernel.org; Jiri Pirko > Subject: Re: [v11,1/4] drivers: jtag: Add JTAG core driver > > > Oleksandr Shamray writes: [..] > I notice the single-open()-per-device lock was dropped by request in an earlier > revision of your patches, but multiple processes trying to drive a single JTAG > master could wreak serious havoc if transactions get interleaved. Would > something like an added JTAG_LOCKCHAIN/UNLOCKCHAIN > ioctl() for exclusive client access be reasonable to prevent this? > Yes, it dropped by recommendation of Greg KH . Greg, what you can suggest about it. May be better to add again single-open()-per-device lock with right locking way like: >if (mutex_lock_interruptible(&jtag->open_lock)) { > return -ERESTARTSYS; >} > >if (jtag->opened) { > mutex_unlock(&jtag->open_lock); > return -EINVAL; >} > >nonseekable_open(inode, file); >file->private_data = jtag; >jtag->opened++; >mutex_unlock(&jtag->open_lock); > Thaks. > -Chip