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Wed, 22 Apr 2020 16:02:52 +0000 Received: from OLAWPA-EXMB10.ad.garmin.com (10.5.144.12) by olawpa-edge5.garmin.com (10.60.4.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1466.3; Wed, 22 Apr 2020 11:02:50 -0500 Received: from OLAWPA-EXMB7.ad.garmin.com (10.5.144.21) by OLAWPA-EXMB10.ad.garmin.com (10.5.144.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1913.5; Wed, 22 Apr 2020 11:02:49 -0500 Received: from OLAWPA-EXMB7.ad.garmin.com ([fe80::68cc:dab9:e96a:c89]) by OLAWPA-EXMB7.ad.garmin.com ([fe80::68cc:dab9:e96a:c89%23]) with mapi id 15.01.1913.007; Wed, 22 Apr 2020 11:02:49 -0500 From: "Karstens, Nate" To: Matthew Wilcox CC: Alexander Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , Richard Henderson , Ivan Kokshaysky , Matt Turner , "James E.J. Bottomley" , Helge Deller , "David S. Miller" , Jakub Kicinski , "linux-fsdevel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-alpha@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "sparclinux@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , David Laight , Changli Gao Subject: RE: [PATCH 1/4] fs: Implement close-on-fork Thread-Topic: [PATCH 1/4] fs: Implement close-on-fork Thread-Index: AQHWFuOUNQrmUX2/BU6CQ6OUTp2yNKiFQqwQgABdCAD//650EA== Date: Wed, 22 Apr 2020 16:02:49 +0000 Message-ID: <6ed7bd08892b4311b70636658321904f@garmin.com> References: <20200420071548.62112-1-nate.karstens@garmin.com> <20200420071548.62112-2-nate.karstens@garmin.com> <20200422154356.GU5820@bombadil.infradead.org> In-Reply-To: <20200422154356.GU5820@bombadil.infradead.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.50.4.7] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-TM-AS-Product-Ver: SMEX-12.5.0.1300-8.5.1020-25372.001 X-TM-AS-Result: No-20.492900-8.000000-10 X-TMASE-MatchedRID: Rp71wniPtoM4HKI/yaqRm/KR06Kw3DzKRiPTMMc/MmlOyROmWLBZSuNb 0aTvicGvSTuOLEQgmVbhVp16EZAE1e34OOTGEFTiB/XUnmGGOOr4qCLIu0mtIDyC5ddG2JcgDsh HkVWp6Z/gF59qS0/NMzzsW2Cgd3ClR0noGmyTNMsHz0YoejTedhlKjo8zguyKSX8n1Gj4wAExhE xXq6zLI1oWex3m0IGtG8983J7kkbz4Z8QQieNUXszWN98iBBeG+PgcXG6KFc5sMPuLZB/IR/hTn o/hWfnfwPb5NDq94CD80wK+80FbY2+4O3SBmLlWHmtCXih7f9P3N59hBwdmnyiCVsScJChxrk+q psJ8hQ9MAraxXAQN9j1Z6/6pkvauPWKLA6/g//v0VCHd+VQiHpRy1HDTPOXaT7zqZowzdpKXD5/ te2xRDy6Ogi9NiuirBEmpoGQQfL5yOVk+FPzL1wYtEovY17GN9pLnYtQ99xIAZTQQTIkkcywmNV NFRFysdzi+MT2hFg7/6J39gwEM6MGfi/dxL5nubMGKOuLn5FURO65VAx9xehRnkhLZOCK9G88rs ck3r8QvJ+I7jC1cP1Mtpl6RMI3caTNicKv7gx9+AWdjDjY8Xfy0wgIDXBCTwUqLhUY4dAI4ULAZ wl+oC+LzNWBegCW2ak1q2nxhDrwLbigRnpKlKSBuGJWwgxArFnn7zLfna4I= X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--20.492900-8.000000 X-TMASE-Version: SMEX-12.5.0.1300-8.5.1020-25372.001 X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-HT: Tenant X-Forefront-Antispam-Report: CIP:204.77.163.244;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:edgetransport.garmin.com;PTR:extedge.garmin.com;CAT:NONE;SFTY:;SFS:(10019020)(376002)(39860400002)(136003)(346002)(396003)(46966005)(4326008)(8936002)(47076004)(86362001)(6916009)(26005)(36756003)(5660300002)(108616005)(2616005)(966005)(53546011)(7416002)(478600001)(7696005)(186003)(336012)(82740400003)(426003)(316002)(8676002)(24736004)(70206006)(7636003)(70586007)(54906003)(356005)(2906002)(246002)(82310400002);DIR:OUT;SFP:1102; X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 6cf3a271-9485-4c7d-0011-08d7e6d69cf6 X-MS-TrafficTypeDiagnostic: SN6PR04MB4319: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-Forefront-PRVS: 03818C953D X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-OriginatorOrg: garmin.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Apr 2020 16:02:52.5232 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 6cf3a271-9485-4c7d-0011-08d7e6d69cf6 X-MS-Exchange-CrossTenant-Id: 38d0d425-ba52-4c0a-a03e-2a65c8e82e2d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=38d0d425-ba52-4c0a-a03e-2a65c8e82e2d;Ip=[204.77.163.244];Helo=[edgetransport.garmin.com] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR04MB4319 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > It's not safe to call system() from a threaded app. That's all. It's ri= ght there in the DESCRIPTION: That is true, but that description is missing from both the Linux man page = and the glibc documentation (https://www.gnu.org/software/libc/manual/html_= mono/libc.html#Running-a-Command). It seems like a minor point that won't b= e noticed until it causes a problem, and problems are rare enough they migh= t go unnoticed for a while. We have removed system() from our application, = but we're also concerned that libraries we integrate will use system() with= out our knowledge. -----Original Message----- From: Matthew Wilcox Sent: Wednesday, April 22, 2020 10:44 To: Karstens, Nate Cc: Alexander Viro ; Jeff Layton ; J. Bruce Fields ; Arnd Bergmann ;= Richard Henderson ; Ivan Kokshaysky ; Matt Turner ; James E.J. Bottomley ; Helge Deller ; David S. Miller <= davem@davemloft.net>; Jakub Kicinski ; linux-fsdevel@vger.= kernel.org; linux-arch@vger.kernel.org; linux-alpha@vger.kernel.org; linux-= parisc@vger.kernel.org; sparclinux@vger.kernel.org; netdev@vger.kernel.org;= linux-kernel@vger.kernel.org; David Laight ; Chan= gli Gao Subject: Re: [PATCH 1/4] fs: Implement close-on-fork CAUTION - EXTERNAL EMAIL: Do not click any links or open any attachments un= less you trust the sender and know the content is safe. On Wed, Apr 22, 2020 at 03:36:09PM +0000, Karstens, Nate wrote: > There was some skepticism about whether our practice of > closing/reopening sockets was advisable. Regardless, it does expose > what I believe to be something that was overlooked in the forking > process model. We posted two solutions to the Austin Group defect tracker= : I don't think it was "overlooked" at all. It's not safe to call system() f= rom a threaded app. That's all. It's right there in the DESCRIPTION: The system() function need not be thread-safe. https://pubs.opengroup.org/onlinepubs/9699919799/functions/system.html > Ultimately the Austin Group felt that close-on-fork was the preferred > approach. I think it's also worth pointing that out Solaris reportedly > has this feature > (https://www.mail-archive.com/austin-group-l@opengroup.org/msg05359.html)= . I am perplexed that the Austin Group thought this was a good idea. ________________________________ CONFIDENTIALITY NOTICE: This email and any attachments are for the sole use= of the intended recipient(s) and contain information that may be Garmin co= nfidential and/or Garmin legally privileged. If you have received this emai= l in error, please notify the sender by reply email and delete the message.= Any disclosure, copying, distribution or use of this communication (includ= ing attachments) by someone other than the intended recipient is prohibited= . Thank you.