Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     David Lechner <david@lechnology.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [PATCH AUTOSEL for 4.15 104/124] clk: fix reentrancy of
 clk_enable() on UP systems
Thread-Topic: [PATCH AUTOSEL for 4.15 104/124] clk: fix reentrancy of
 clk_enable() on UP systems
Thread-Index: AQHTv5nJGUwlmQMprEeYWg0XJMUef6PXtiQAgAARnQA=
Date:   Mon, 19 Mar 2018 16:58:20 +0000
Message-ID: <20180319165818.7bxduuoaeptjsvoh@sasha-lappy>
References: <20180319154645.11350-1-alexander.levin@microsoft.com>
 <20180319154645.11350-104-alexander.levin@microsoft.com>
 <6a944b80-c86c-ca23-5ada-f088d84c9a80@lechnology.com>
In-Reply-To: <6a944b80-c86c-ca23-5ada-f088d84c9a80@lechnology.com>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: microsoft.com does not designate
 permitted sender hosts)
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: text/plain; charset="us-ascii"
Content-ID: <56BD72410A817A4EB4418314CD7419D5@namprd21.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: d8b3e310-c27c-42c0-4d6b-08d58dba9e77
X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Mar 2018 16:58:20.2954
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB0808
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Mar 19, 2018 at 10:55:16AM -0500, David Lechner wrote:
>On 03/19/2018 10:48 AM, Sasha Levin wrote:
>>From: David Lechner <david@lechnology.com>
>>
>>[ 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 se=
t
>>flags in this case so that we are not returning an uninitialized value.
>>
>>Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
>>Signed-off-by: David Lechner <david@lechnology.com>
>>Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
>>---
>
>I don't know of any existing bugs in v4.15 that this fixes, so I don't
>think this really fits the criteria for stable.
>

I'll remove it, thanks David!

--=20

Thanks,
Sasha=