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Thu, 22 Sep 2022 13:55:29 +0000 From: Wilco Dijkstra To: Adhemerval Zanella Netto , 'GNU C Library' Subject: Re: [PATCH] Use C11 atomics instead atomic_decrement_and_test Thread-Topic: [PATCH] Use C11 atomics instead atomic_decrement_and_test Thread-Index: AQHYw4wGPP2u7at5Q0WaojjkgK7/Z63qN8GAgAFTSYI= Date: Thu, 22 Sep 2022 13:55:28 +0000 Message-ID: References: In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-GB X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: Authentication-Results-Original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com; x-ms-traffictypediagnostic: AS4PR08MB7901:EE_|AS4PR08MB7508:EE_|DBAEUR03FT062:EE_|PA4PR08MB5919:EE_ X-MS-Office365-Filtering-Correlation-Id: 4b1674c3-3693-47ad-fbc3-08da9ca221e8 x-checkrecipientrouted: true nodisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0; X-Microsoft-Antispam-Message-Info-Original: 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 X-Forefront-Antispam-Report-Untrusted: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:AS4PR08MB7901.eurprd08.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230022)(4636009)(376002)(346002)(366004)(136003)(396003)(39860400002)(451199015)(7696005)(26005)(9686003)(110136005)(478600001)(71200400001)(41300700001)(86362001)(33656002)(122000001)(55016003)(38100700002)(6506007)(38070700005)(83380400001)(186003)(316002)(52536014)(5660300002)(2906002)(4744005)(8676002)(76116006)(91956017)(64756008)(66556008)(66476007)(66946007)(66446008)(8936002);DIR:OUT;SFP:1101; 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X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Sep 2022 13:55:39.3742 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4b1674c3-3693-47ad-fbc3-08da9ca221e8 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[63.35.35.123];Helo=[64aa7808-outbound-1.mta.getcheckrecipient.com] X-MS-Exchange-CrossTenant-AuthSource: DBAEUR03FT062.eop-EUR03.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PA4PR08MB5919 X-Spam-Status: No, score=-5.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,FORGED_SPF_HELO,KAM_DMARC_NONE,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_NONE,TXREP,UNPARSEABLE_RELAY autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Hi Adhemerval,=0A= =0A= > +=A0 if (atomic_fetch_add_relaxed (&pthread->nr_refs, -1) !=3D 1)=0A= >=A0=A0=A0=A0=A0 return;=0A= >=A0 =0A= >=A0=A0=A0 /* Withdraw this thread from the thread ID lookup table.=A0 */= =0A= =0A= > Ok (and I am not sure why __pthread_create_internal usage does not use at= omic at all).=0A= =0A= Yes the non-atomic increment is a bug, an in/decrement could be lost if the= re is=0A= a data race. Is it still used or could we default to nptl and remove the ht= l stuff?=0A= =0A= > I am not sure if MO is suffice here, shouldn't it synchronize with the up= date=0A= > from __pthread_create_internal?=0A= =0A= As discussed in my previous mail, __pthread_total and __nptl_nthreads are s= imple=0A= counters that decide when to call exit for the last thread.=0A= =0A= > Ok, although this code is not used anywhere (neither for testing). Maybe = it would be better=0A= > to just remove it.=0A= =0A= Yes, it looks like it was added 20 years ago as some kind of internal bench= mark - I'll remove it=0A= in the commit.=0A= =0A= Cheers,=0A= Wilco=