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x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=microsoft.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934599AbeCSP6z (ORCPT ); Mon, 19 Mar 2018 11:58:55 -0400 Received: from mail-by2nam01on0117.outbound.protection.outlook.com ([104.47.34.117]:58464 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934643AbeCSP4t (ORCPT ); Mon, 19 Mar 2018 11:56:49 -0400 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: David Lechner , Stephen Boyd , Sasha Levin Subject: [PATCH AUTOSEL for 4.14 78/97] clk: fix reentrancy of clk_enable() on UP systems Thread-Topic: [PATCH AUTOSEL for 4.14 78/97] clk: fix reentrancy of clk_enable() on UP systems Thread-Index: AQHTv5rOJn7Qlcmz20mozFRzI8zB+w== Date: Mon, 19 Mar 2018 15:56:14 +0000 Message-ID: <20180319155411.12348-78-alexander.levin@microsoft.com> References: <20180319155411.12348-1-alexander.levin@microsoft.com> In-Reply-To: <20180319155411.12348-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1031;7:eQW/4OTd2aYAanFFvsIj/Kv4EuvO3Tv4Jj6koNytU5nJl1IgzjWWAaKAeeWtcCvtcPJLOb1jREC28Uof6LxLx8OA3VRK8BhQlDA/Kcv++ZDWeWHlp1xOE9smSEeMwb9EKL/4YoHVV1SFlb2yiAaAiC6TmBxHl1D3r9EpAjUYc2VjjKePiqIwyyjyEQIs/s1y7BYGrt/4GY3Pz/NK4WeegNJ3UEieT9Gq4s7x3DdVCRHrocFyKyFzPEhKfeiPdnVu;20:R8ELAiaCLH7NPIHpeQF4LG7bM+CRLJ3/bN8zYwVXo+AP1MeScFVkQoeYS5RrSzbVkCe/+gMiFFpD9doLPmANbJGrwG+NbDuh9kcq9ln/sQX04PUWt6k27MDFzuPBO9u+DzT4jB90rdSIHrJD6hQ8Cwe/cQcaj12/pl3zYcawkk0= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 8933dfd8-4ffd-4409-e348-08d58db20075 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1031; 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x-microsoft-antispam-message-info: 3wg99tE9Ti+P9MAFhr6PoEyURqgugt5z9h4cp6cQ/uDk6EWXF6Hi+azxxw434NExKF718uJgZJ4DXJ+NCBSuerednP7weHb55U148z/bnVRA11z0mP01ZKnJx37QA94Bpy/Gf+LwKvHS+FuEjKbtN0z4LQDgBLtvi6mnH85GexJlJJN3FoQtWGO4xvBDaFe2wX1FISHGY9MZeLcZrT5xKx8uRP1ZH9hnPYedojaPIbw2nqgyf2yBQ7nRBW0byT8wt7CUgjcH0q04/JTW9PiZNkwIiz7ihVYtCsGs69sJpDlSMQDccG+ewU0FGszgn6I35ebrbaDmjH/g84IKZxIdRw== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8933dfd8-4ffd-4409-e348-08d58db20075 X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Mar 2018 15:56:14.2538 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1031 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: David Lechner [ Upstream commit a12aa8a68dfef5de181f2e555aa950a0ab05411f ] Reentrant calls to clk_enable() are not working on UP systems. This is caused by the fact spin_trylock_irqsave() always returns true when CONFIG_SMP=3Dn (and CONFIG_DEBUG_SPINLOCK=3Dn) which causes the reference counting to not work correctly when clk_enable_lock() is called twice before clk_enable_unlock() is called (this happens when clk_enable() is called from within another clk_enable()). This fixes the problem by skipping the call to spin_trylock_irqsave() on UP systems and relying solely on reference counting. We also make sure to set flags in this case so that we are not returning an uninitialized value. Suggested-by: Stephen Boyd Signed-off-by: David Lechner Signed-off-by: Stephen Boyd Signed-off-by: Sasha Levin --- drivers/clk/clk.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index c8d83acda006..f6c9d6205d85 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -119,10 +119,18 @@ static unsigned long clk_enable_lock(void) { unsigned long flags; =20 - if (!spin_trylock_irqsave(&enable_lock, flags)) { + /* + * On UP systems, spin_trylock_irqsave() always returns true, even if + * we already hold the lock. So, in that case, we rely only on + * reference counting. + */ + if (!IS_ENABLED(CONFIG_SMP) || + !spin_trylock_irqsave(&enable_lock, flags)) { if (enable_owner =3D=3D current) { enable_refcnt++; __acquire(enable_lock); + if (!IS_ENABLED(CONFIG_SMP)) + local_save_flags(flags); return flags; } spin_lock_irqsave(&enable_lock, flags); --=20 2.14.1