From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Subject: Re: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void Date: Fri, 30 May 2014 20:16:59 +0200 Message-ID: <5388CB1B.3090802@metafoo.de> References: <20140530094025.3b78301e@canb.auug.org.au> <1401449454-30895-1-git-send-email-berthe.ab@gmail.com> <1401449454-30895-2-git-send-email-berthe.ab@gmail.com> <5388C0F1.90503@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5388C0F1.90503@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: David Daney Cc: abdoulaye berthe , Geert Uytterhoeven , Linus Walleij , Alexandre Courbot , m@bues.ch, "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linux MIPS Mailing List , "linuxppc-dev@lists.ozlabs.org" , Linux-sh list , linux-wireless , patches@opensource.wolfsonmicro.com, "linux-input@vger.kernel.org" , "linux-leds@vger.kernel.org" , Linux Media Mailing List , linux-samsungsoc@vger.kernel.org, spear-devel@list.st.com, platform-driver-x86@vg List-Id: linux-gpio@vger.kernel.org On 05/30/2014 07:33 PM, David Daney wrote: > On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote: >> On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe >> wrote: >>> --- a/drivers/gpio/gpiolib.c >>> +++ b/drivers/gpio/gpiolib.c >>> @@ -1263,10 +1263,9 @@ static void gpiochip_irqchip_remove(struct >>> gpio_chip *gpiochip); >>> * >>> * A gpio_chip with any GPIOs still requested may not be removed. >>> */ >>> -int gpiochip_remove(struct gpio_chip *chip) >>> +void gpiochip_remove(struct gpio_chip *chip) >>> { >>> unsigned long flags; >>> - int status = 0; >>> unsigned id; >>> >>> acpi_gpiochip_remove(chip); >>> @@ -1278,24 +1277,15 @@ int gpiochip_remove(struct gpio_chip *chip) >>> of_gpiochip_remove(chip); >>> >>> for (id = 0; id < chip->ngpio; id++) { >>> - if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) { >>> - status = -EBUSY; >>> - break; >>> - } >>> - } >>> - if (status == 0) { >>> - for (id = 0; id < chip->ngpio; id++) >>> - chip->desc[id].chip = NULL; >>> - >>> - list_del(&chip->list); >>> + if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) >>> + panic("gpio: removing gpiochip with gpios still >>> requested\n"); >> >> panic? > > NACK to the patch for this reason. The strongest thing you should do here > is WARN. > > That said, I am not sure why we need this whole patch set in the first place. Well, what currently happens when you remove a device that is a provider of a gpio_chip which is still in use, is that the kernel crashes. Probably with a rather cryptic error message. So this patch doesn't really change the behavior, but makes it more explicit what is actually wrong. And even if you replace the panic() by a WARN() it will again just crash slightly later. This is a design flaw in the GPIO subsystem that needs to be fixed. - Lars From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Fri, 30 May 2014 20:52:49 +0200 (CEST) Received: from smtp-out-150.synserver.de ([212.40.185.150]:1077 "EHLO smtp-out-147.synserver.de" rhost-flags-OK-OK-OK-FAIL) by eddie.linux-mips.org with ESMTP id S6822106AbaE3SwrgoR0z (ORCPT ); Fri, 30 May 2014 20:52:47 +0200 Received: (qmail 29647 invoked by uid 0); 30 May 2014 18:17:05 -0000 X-SynServer-TrustedSrc: 1 X-SynServer-AuthUser: lars@metafoo.de X-SynServer-PPID: 29400 Received: from ppp-212-114-237-253.dynamic.mnet-online.de (HELO ?192.168.178.23?) [212.114.237.253] by 217.119.54.87 with AES256-SHA encrypted SMTP; 30 May 2014 18:17:02 -0000 Message-ID: <5388CB1B.3090802@metafoo.de> Date: Fri, 30 May 2014 20:16:59 +0200 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131103 Icedove/17.0.10 MIME-Version: 1.0 To: David Daney CC: abdoulaye berthe , Geert Uytterhoeven , Linus Walleij , Alexandre Courbot , m@bues.ch, "linux-gpio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linux MIPS Mailing List , "linuxppc-dev@lists.ozlabs.org" , Linux-sh list , linux-wireless , patches@opensource.wolfsonmicro.com, "linux-input@vger.kernel.org" , "linux-leds@vger.kernel.org" , Linux Media Mailing List , linux-samsungsoc@vger.kernel.org, spear-devel@list.st.com, platform-driver-x86@vger.kernel.org, "netdev@vger.kernel.org" , driverdevel Subject: Re: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void References: <20140530094025.3b78301e@canb.auug.org.au> <1401449454-30895-1-git-send-email-berthe.ab@gmail.com> <1401449454-30895-2-git-send-email-berthe.ab@gmail.com> <5388C0F1.90503@gmail.com> In-Reply-To: <5388C0F1.90503@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 40393 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: lars@metafoo.de Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 05/30/2014 07:33 PM, David Daney wrote: > On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote: >> On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe >> wrote: >>> --- a/drivers/gpio/gpiolib.c >>> +++ b/drivers/gpio/gpiolib.c >>> @@ -1263,10 +1263,9 @@ static void gpiochip_irqchip_remove(struct >>> gpio_chip *gpiochip); >>> * >>> * A gpio_chip with any GPIOs still requested may not be removed. >>> */ >>> -int gpiochip_remove(struct gpio_chip *chip) >>> +void gpiochip_remove(struct gpio_chip *chip) >>> { >>> unsigned long flags; >>> - int status = 0; >>> unsigned id; >>> >>> acpi_gpiochip_remove(chip); >>> @@ -1278,24 +1277,15 @@ int gpiochip_remove(struct gpio_chip *chip) >>> of_gpiochip_remove(chip); >>> >>> for (id = 0; id < chip->ngpio; id++) { >>> - if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) { >>> - status = -EBUSY; >>> - break; >>> - } >>> - } >>> - if (status == 0) { >>> - for (id = 0; id < chip->ngpio; id++) >>> - chip->desc[id].chip = NULL; >>> - >>> - list_del(&chip->list); >>> + if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) >>> + panic("gpio: removing gpiochip with gpios still >>> requested\n"); >> >> panic? > > NACK to the patch for this reason. The strongest thing you should do here > is WARN. > > That said, I am not sure why we need this whole patch set in the first place. Well, what currently happens when you remove a device that is a provider of a gpio_chip which is still in use, is that the kernel crashes. Probably with a rather cryptic error message. So this patch doesn't really change the behavior, but makes it more explicit what is actually wrong. And even if you replace the panic() by a WARN() it will again just crash slightly later. This is a design flaw in the GPIO subsystem that needs to be fixed. - Lars From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Date: Fri, 30 May 2014 18:16:59 +0000 Subject: Re: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void Message-Id: <5388CB1B.3090802@metafoo.de> List-Id: References: <20140530094025.3b78301e@canb.auug.org.au> <1401449454-30895-1-git-send-email-berthe.ab@gmail.com> <1401449454-30895-2-git-send-email-berthe.ab@gmail.com> <5388C0F1.90503@gmail.com> In-Reply-To: <5388C0F1.90503@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On 05/30/2014 07:33 PM, David Daney wrote: > On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote: >> On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe >> wrote: >>> --- a/drivers/gpio/gpiolib.c >>> +++ b/drivers/gpio/gpiolib.c >>> @@ -1263,10 +1263,9 @@ static void gpiochip_irqchip_remove(struct >>> gpio_chip *gpiochip); >>> * >>> * A gpio_chip with any GPIOs still requested may not be removed. >>> */ >>> -int gpiochip_remove(struct gpio_chip *chip) >>> +void gpiochip_remove(struct gpio_chip *chip) >>> { >>> unsigned long flags; >>> - int status = 0; >>> unsigned id; >>> >>> acpi_gpiochip_remove(chip); >>> @@ -1278,24 +1277,15 @@ int gpiochip_remove(struct gpio_chip *chip) >>> of_gpiochip_remove(chip); >>> >>> for (id = 0; id < chip->ngpio; id++) { >>> - if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) { >>> - status = -EBUSY; >>> - break; >>> - } >>> - } >>> - if (status = 0) { >>> - for (id = 0; id < chip->ngpio; id++) >>> - chip->desc[id].chip = NULL; >>> - >>> - list_del(&chip->list); >>> + if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) >>> + panic("gpio: removing gpiochip with gpios still >>> requested\n"); >> >> panic? > > NACK to the patch for this reason. The strongest thing you should do here > is WARN. > > That said, I am not sure why we need this whole patch set in the first place. Well, what currently happens when you remove a device that is a provider of a gpio_chip which is still in use, is that the kernel crashes. Probably with a rather cryptic error message. So this patch doesn't really change the behavior, but makes it more explicit what is actually wrong. And even if you replace the panic() by a WARN() it will again just crash slightly later. This is a design flaw in the GPIO subsystem that needs to be fixed. - Lars From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out-147.synserver.de (smtp-out-147.synserver.de [212.40.185.147]) by lists.ozlabs.org (Postfix) with ESMTP id ECF9C1A06F8 for ; Sat, 31 May 2014 04:37:24 +1000 (EST) Message-ID: <5388CB1B.3090802@metafoo.de> Date: Fri, 30 May 2014 20:16:59 +0200 From: Lars-Peter Clausen MIME-Version: 1.0 To: David Daney Subject: Re: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void References: <20140530094025.3b78301e@canb.auug.org.au> <1401449454-30895-1-git-send-email-berthe.ab@gmail.com> <1401449454-30895-2-git-send-email-berthe.ab@gmail.com> <5388C0F1.90503@gmail.com> In-Reply-To: <5388C0F1.90503@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Cc: platform-driver-x86@vger.kernel.org, Alexandre Courbot , patches@opensource.wolfsonmicro.com, Linux MIPS Mailing List , "netdev@vger.kernel.org" , Linus Walleij , Linux-sh list , linux-wireless , "linux-kernel@vger.kernel.org" , spear-devel@list.st.com, linux-samsungsoc@vger.kernel.org, "linux-gpio@vger.kernel.org" , Geert Uytterhoeven , "linux-leds@vger.kernel.org" , m@bues.ch, "linux-input@vger.kernel.org" , driverdevel , Linux Media Mailing List , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" , abdoulaye berthe List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 05/30/2014 07:33 PM, David Daney wrote: > On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote: >> On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe >> wrote: >>> --- a/drivers/gpio/gpiolib.c >>> +++ b/drivers/gpio/gpiolib.c >>> @@ -1263,10 +1263,9 @@ static void gpiochip_irqchip_remove(struct >>> gpio_chip *gpiochip); >>> * >>> * A gpio_chip with any GPIOs still requested may not be removed. >>> */ >>> -int gpiochip_remove(struct gpio_chip *chip) >>> +void gpiochip_remove(struct gpio_chip *chip) >>> { >>> unsigned long flags; >>> - int status = 0; >>> unsigned id; >>> >>> acpi_gpiochip_remove(chip); >>> @@ -1278,24 +1277,15 @@ int gpiochip_remove(struct gpio_chip *chip) >>> of_gpiochip_remove(chip); >>> >>> for (id = 0; id < chip->ngpio; id++) { >>> - if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) { >>> - status = -EBUSY; >>> - break; >>> - } >>> - } >>> - if (status == 0) { >>> - for (id = 0; id < chip->ngpio; id++) >>> - chip->desc[id].chip = NULL; >>> - >>> - list_del(&chip->list); >>> + if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) >>> + panic("gpio: removing gpiochip with gpios still >>> requested\n"); >> >> panic? > > NACK to the patch for this reason. The strongest thing you should do here > is WARN. > > That said, I am not sure why we need this whole patch set in the first place. Well, what currently happens when you remove a device that is a provider of a gpio_chip which is still in use, is that the kernel crashes. Probably with a rather cryptic error message. So this patch doesn't really change the behavior, but makes it more explicit what is actually wrong. And even if you replace the panic() by a WARN() it will again just crash slightly later. This is a design flaw in the GPIO subsystem that needs to be fixed. - Lars From mboxrd@z Thu Jan 1 00:00:00 1970 From: lars@metafoo.de (Lars-Peter Clausen) Date: Fri, 30 May 2014 20:16:59 +0200 Subject: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void In-Reply-To: <5388C0F1.90503@gmail.com> References: <20140530094025.3b78301e@canb.auug.org.au> <1401449454-30895-1-git-send-email-berthe.ab@gmail.com> <1401449454-30895-2-git-send-email-berthe.ab@gmail.com> <5388C0F1.90503@gmail.com> Message-ID: <5388CB1B.3090802@metafoo.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/30/2014 07:33 PM, David Daney wrote: > On 05/30/2014 04:39 AM, Geert Uytterhoeven wrote: >> On Fri, May 30, 2014 at 1:30 PM, abdoulaye berthe >> wrote: >>> --- a/drivers/gpio/gpiolib.c >>> +++ b/drivers/gpio/gpiolib.c >>> @@ -1263,10 +1263,9 @@ static void gpiochip_irqchip_remove(struct >>> gpio_chip *gpiochip); >>> * >>> * A gpio_chip with any GPIOs still requested may not be removed. >>> */ >>> -int gpiochip_remove(struct gpio_chip *chip) >>> +void gpiochip_remove(struct gpio_chip *chip) >>> { >>> unsigned long flags; >>> - int status = 0; >>> unsigned id; >>> >>> acpi_gpiochip_remove(chip); >>> @@ -1278,24 +1277,15 @@ int gpiochip_remove(struct gpio_chip *chip) >>> of_gpiochip_remove(chip); >>> >>> for (id = 0; id < chip->ngpio; id++) { >>> - if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) { >>> - status = -EBUSY; >>> - break; >>> - } >>> - } >>> - if (status == 0) { >>> - for (id = 0; id < chip->ngpio; id++) >>> - chip->desc[id].chip = NULL; >>> - >>> - list_del(&chip->list); >>> + if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) >>> + panic("gpio: removing gpiochip with gpios still >>> requested\n"); >> >> panic? > > NACK to the patch for this reason. The strongest thing you should do here > is WARN. > > That said, I am not sure why we need this whole patch set in the first place. Well, what currently happens when you remove a device that is a provider of a gpio_chip which is still in use, is that the kernel crashes. Probably with a rather cryptic error message. So this patch doesn't really change the behavior, but makes it more explicit what is actually wrong. And even if you replace the panic() by a WARN() it will again just crash slightly later. This is a design flaw in the GPIO subsystem that needs to be fixed. - Lars