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[2620:137:e000::1:20]) by mx.google.com with ESMTP id z26-20020a637e1a000000b00563a0c1bf06si12974238pgc.428.2023.08.03.08.11.00; Thu, 03 Aug 2023 08:11:21 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=aculab.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236767AbjHCOl1 (ORCPT + 99 others); Thu, 3 Aug 2023 10:41:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236028AbjHCOlJ (ORCPT ); Thu, 3 Aug 2023 10:41:09 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6DAC3A80 for ; Thu, 3 Aug 2023 07:40:16 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-93-Yef4x2TXMjORgJxQ4THDUQ-1; Thu, 03 Aug 2023 15:39:39 +0100 X-MC-Unique: Yef4x2TXMjORgJxQ4THDUQ-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Thu, 3 Aug 2023 15:39:38 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Thu, 3 Aug 2023 15:39:38 +0100 From: David Laight To: "'paulmck@kernel.org'" , Alan Huang CC: Joel Fernandes , Eric Dumazet , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "rcu@vger.kernel.org" , "roman.gushchin@linux.dev" Subject: RE: Question about the barrier() in hlist_nulls_for_each_entry_rcu() Thread-Topic: Question about the barrier() in hlist_nulls_for_each_entry_rcu() Thread-Index: AQHZxhH18xsGyGi6wkSgE8eJxYMp7K/Yo3ZQ Date: Thu, 3 Aug 2023 14:39:38 +0000 Message-ID: <9905e2f8e28246929be7b77b78c07fb4@AcuMS.aculab.com> References: <1E0741E0-2BD9-4FA3-BA41-4E83315A10A8@joelfernandes.org> <1AF98387-B78C-4556-BE2E-E8F88ADACF8A@gmail.com> <43d29007-3c59-4497-a1e5-26f182a7f4c5@paulmck-laptop> <784ABF9D-303F-4FC8-8AFF-A3FF319B4E7A@gmail.com> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: base64 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org RnJvbTogUGF1bCBFLiBNY0tlbm5leQ0KPiBTZW50OiAwMyBBdWd1c3QgMjAyMyAxNDo1NA0KLi4u Lg0KPiA+ID4gSWYgYm90aCBhcmUgUkVBRF9PTkNFKCksIHlvdSBzaG91bGQgbm90IG5lZWQgdGhl IGJhcnJpZXIoKS4gIFVubGVzcyB0aGVyZQ0KPiA+ID4gaXMgc29tZSBvdGhlciBjb2RlIG5vdCBz aG93biBpbiB5b3VyIGV4YW1wbGUgdGhhdCByZXF1aXJlcyBpdCwgdGhhdCBpcy4NCj4gPg0KPiA+ IEFuZCB1bmxlc3MgdGhlIGNvbXBpbGVyIGhhcyBhIGJ1Zy4gOikNCj4gPg0KPiA+IFNvLCB0aGUg YmFycmllcigpIGluIGhsaXN0X251bGxzX2Zvcl9lYWNoX2VudHJ5X3JjdSgpIGlzIGEgd29ya2Fy b3VuZCBmb3IgYSBjb21waWxlciBidWcuDQo+IA0KPiBGYWlyIGVub3VnaCEhISAgOy0pDQoNCkV4 Y2VwdCB0aGF0IGl0IGlzIGxpa2VseSB0aGF0IHRoZSBjb21waWxlciBidWcgaXMgYXZvaWRlZCBi eSB0aGUNCmltcGxlbWVudGF0aW9uIG9mIFJFQURfT05DRSgpIHJhdGhlciB0aGFuIEFDQ0VTU19P TkNFKCkuDQoNCkFsc28gdGhlIGNvZGUgdGhhdCBsb29wZWQgZm9yZXZlciAoVURQIHJlY2VpdmUg c29ja2V0IGxvb2t1cCkNCm5vIGxvbmdlciBoYXMgdGhlIHJldHJ5IC0gd2hpY2ggaXMgYSBkaWZm ZXJlbnQgYnVnLg0KSWYgYSBzb2NrZXQgcmVoYXNoIGhpdHMgdGhlIGxvb2t1cCB0aGVuIGFuIGVy cm9uZW91cyBJQ01QDQoncG9ydCB1bnJlYWNoYWJsZScgaXMgc2VudCByYXRoZXIgdGhhbiBkb2lu ZyBhIHJlc2Nhbi4NCg0KCURhdmlkDQogDQoNCi0NClJlZ2lzdGVyZWQgQWRkcmVzcyBMYWtlc2lk ZSwgQnJhbWxleSBSb2FkLCBNb3VudCBGYXJtLCBNaWx0b24gS2V5bmVzLCBNSzEgMVBULCBVSw0K UmVnaXN0cmF0aW9uIE5vOiAxMzk3Mzg2IChXYWxlcykNCg==