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=?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Subject: Re: [PATCH v2] misc: atmel-ssc: lock with mutex instead of spinlock Message-ID: <20200629223004.GC3800@piout.net> References: <50f0d7fa107f318296afb49477c3571e4d6978c5.1592998403.git.mirq-linux@rere.qmqm.pl> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <50f0d7fa107f318296afb49477c3571e4d6978c5.1592998403.git.mirq-linux@rere.qmqm.pl> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Ludovic Desroches , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gMjQvMDYvMjAyMCAxMzozNTo0MSswMjAwLCBNaWNoYcWCIE1pcm9zxYJhdyB3cm90ZToKPiBV 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version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44892C433E0 for ; Mon, 29 Jun 2020 22:30:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C0982076C for ; Mon, 29 Jun 2020 22:30:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728393AbgF2WaJ (ORCPT ); Mon, 29 Jun 2020 18:30:09 -0400 Received: from relay7-d.mail.gandi.net ([217.70.183.200]:40965 "EHLO relay7-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726951AbgF2WaI (ORCPT ); Mon, 29 Jun 2020 18:30:08 -0400 X-Originating-IP: 86.202.110.81 Received: from localhost (lfbn-lyo-1-15-81.w86-202.abo.wanadoo.fr [86.202.110.81]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay7-d.mail.gandi.net (Postfix) with ESMTPSA id AAEDB20009; Mon, 29 Jun 2020 22:30:04 +0000 (UTC) Date: Tue, 30 Jun 2020 00:30:04 +0200 From: Alexandre Belloni To: =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Cc: Nicolas Ferre , Arnd Bergmann , Greg Kroah-Hartman , Ludovic Desroches , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] misc: atmel-ssc: lock with mutex instead of spinlock Message-ID: <20200629223004.GC3800@piout.net> References: <50f0d7fa107f318296afb49477c3571e4d6978c5.1592998403.git.mirq-linux@rere.qmqm.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <50f0d7fa107f318296afb49477c3571e4d6978c5.1592998403.git.mirq-linux@rere.qmqm.pl> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/06/2020 13:35:41+0200, Michał Mirosław wrote: > Uninterruptible context is not needed in the driver and causes lockdep > warning because of mutex taken in of_alias_get_id(). Convert the lock to > mutex to avoid the issue. > > Cc: stable@vger.kernel.org > Fixes: 099343c64e16 ("ARM: at91: atmel-ssc: add device tree support") > Signed-off-by: Michał Mirosław Acked-by: Alexandre Belloni > --- > v2: rebased onto v5.7.5, added Fixes tag > --- > drivers/misc/atmel-ssc.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/misc/atmel-ssc.c b/drivers/misc/atmel-ssc.c > index ab4144ea1f11..d6cd5537126c 100644 > --- a/drivers/misc/atmel-ssc.c > +++ b/drivers/misc/atmel-ssc.c > @@ -10,7 +10,7 @@ > #include > #include > #include > -#include > +#include > #include > #include > #include > @@ -20,7 +20,7 @@ > #include "../../sound/soc/atmel/atmel_ssc_dai.h" > > /* Serialize access to ssc_list and user count */ > -static DEFINE_SPINLOCK(user_lock); > +static DEFINE_MUTEX(user_lock); > static LIST_HEAD(ssc_list); > > struct ssc_device *ssc_request(unsigned int ssc_num) > @@ -28,7 +28,7 @@ struct ssc_device *ssc_request(unsigned int ssc_num) > int ssc_valid = 0; > struct ssc_device *ssc; > > - spin_lock(&user_lock); > + mutex_lock(&user_lock); > list_for_each_entry(ssc, &ssc_list, list) { > if (ssc->pdev->dev.of_node) { > if (of_alias_get_id(ssc->pdev->dev.of_node, "ssc") > @@ -44,18 +44,18 @@ struct ssc_device *ssc_request(unsigned int ssc_num) > } > > if (!ssc_valid) { > - spin_unlock(&user_lock); > + mutex_unlock(&user_lock); > pr_err("ssc: ssc%d platform device is missing\n", ssc_num); > return ERR_PTR(-ENODEV); > } > > if (ssc->user) { > - spin_unlock(&user_lock); > + mutex_unlock(&user_lock); > dev_dbg(&ssc->pdev->dev, "module busy\n"); > return ERR_PTR(-EBUSY); > } > ssc->user++; > - spin_unlock(&user_lock); > + mutex_unlock(&user_lock); > > clk_prepare(ssc->clk); > > @@ -67,14 +67,14 @@ void ssc_free(struct ssc_device *ssc) > { > bool disable_clk = true; > > - spin_lock(&user_lock); > + mutex_lock(&user_lock); > if (ssc->user) > ssc->user--; > else { > disable_clk = false; > dev_dbg(&ssc->pdev->dev, "device already free\n"); > } > - spin_unlock(&user_lock); > + mutex_unlock(&user_lock); > > if (disable_clk) > clk_unprepare(ssc->clk); > @@ -237,9 +237,9 @@ static int ssc_probe(struct platform_device *pdev) > return -ENXIO; > } > > - spin_lock(&user_lock); > + mutex_lock(&user_lock); > list_add_tail(&ssc->list, &ssc_list); > - spin_unlock(&user_lock); > + mutex_unlock(&user_lock); > > platform_set_drvdata(pdev, ssc); > > @@ -258,9 +258,9 @@ static int ssc_remove(struct platform_device *pdev) > > ssc_sound_dai_remove(ssc); > > - spin_lock(&user_lock); > + mutex_lock(&user_lock); > list_del(&ssc->list); > - spin_unlock(&user_lock); > + mutex_unlock(&user_lock); > > return 0; > } > -- > 2.20.1 > -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com