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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 S965953AbeCSQGi (ORCPT ); Mon, 19 Mar 2018 12:06:38 -0400 Received: from mail-by2nam01on0122.outbound.protection.outlook.com ([104.47.34.122]:13968 "EHLO NAM01-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965910AbeCSQGe (ORCPT ); Mon, 19 Mar 2018 12:06:34 -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 4.9 272/281] clk: fix reentrancy of clk_enable() on UP systems Thread-Topic: [PATCH AUTOSEL for 4.9 272/281] clk: fix reentrancy of clk_enable() on UP systems Thread-Index: AQHTv5vLDiFOXcFh5UOB0DjwHhEMQA== Date: Mon, 19 Mar 2018 16:03:17 +0000 Message-ID: <20180319155742.13731-272-alexander.levin@microsoft.com> References: <20180319155742.13731-1-alexander.levin@microsoft.com> In-Reply-To: <20180319155742.13731-1-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;DM5PR2101MB0728;7:IKle4z4uGBT/1F0piAOTi/6400thTFj/X1I3zY+Yq+G7j8xtKsA7M/aTM9vj5IgMK5KoyQZdUlp2DoqMq0wGMZJCM0LzdCRm5ambZ3PjXym9BtVx87GRqL4UWRCPieASKlzvy6VWZ1skOlDoiXGMwq5XUYVOpouvlTWfraVibjJwonH/U6hhmanGH/K7JUU8MYa8Hgi9LvKxXJNWXswJA3NlNs76eUM8chfGDA7VyFnyW+bHwcUEfctnEhpOMNIl;20:81d1993AwgeHvMbcVTbGNGKCYBomsJGrnMToqMv0MnRJQNZw8MIR6LZCjgXjgxlHa4QM+yWQn968YeCZchDr6lIc6FcttGDXa6DgSkO/tg5xbFe8jREnjUYmpJJRn9iZoFy0WCjHRokS5g0Qjj0Nv7MLfaHITUqMQWBh6G7MCfs= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: d2f3f9ef-a35e-48f1-738c-08d58db36247 x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB0728; 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x-microsoft-antispam-message-info: NpW+P93MVrk0ijvE1MoUJQfHPaJcxTLnnzF+WfciAoIr7KenCigL98BLhCIjKfPTgkDhjc2JA5bNndXSrpUX4ttwcMyLxq7ARvfQ6Ntc51hcBtDkkN2X/JlTbkc611jQjulLmeVZdhiOHfj6lvMMknLFNuIT4TiFQDDyxrTme6aTQFyaKt5cBR5ah9qQ4tLwmeBotcNAFGKulUFQwWHLRnKgIYe6T9lcSaMtH6P1EeiNATh46LNAImiXqW3ZEkDw0i6l1+dNBrX620h/kq2RR3zNaBTbSl4VvnQCViJ8yoDmyuJgxhsnRMx7jfKgO6Y7j68NAKmacDsgUOmeHySRxw== 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: d2f3f9ef-a35e-48f1-738c-08d58db36247 X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Mar 2018 16:03:17.7742 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB0728 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 0fb39fe217d1..33565a434527 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