From: Dan Carpenter <dan.carpenter@oracle.com>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Linux MIPS Mailing List <linux-mips@linux-mips.org>,
David Daney <ddaney.cavm@gmail.com>,
Linux-sh list <linux-sh@vger.kernel.org>,
Greg KH <greg@kroah.com>,
Linus Walleij <linus.walleij@linaro.org>,
platform-driver-x86@vger.kernel.org,
"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
driverdevel <devel@driverdev.osuosl.org>,
Alexandre Courbot <gnurou@gmail.com>,
patches@opensource.wolfsonmicro.com,
linux-samsungsoc@vger.kernel.org,
Geert Uytterhoeven <geert@linux-m68k.org>,
"linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
spear-devel@list.st.com,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
m@bues.ch,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
abdoulaye berthe <berthe.ab@gmail.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void
Date: Sat, 31 May 2014 15:19:14 +0300 [thread overview]
Message-ID: <20140531121914.GM15585@mwanda> (raw)
In-Reply-To: <5389864B.4000107@metafoo.de>
On Sat, May 31, 2014 at 09:35:39AM +0200, Lars-Peter Clausen wrote:
> On 05/31/2014 01:29 AM, Greg KH wrote:
> >On Fri, May 30, 2014 at 08:16:59PM +0200, Lars-Peter Clausen wrote:
> >>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 <berthe.ab@gmail.com>
> >>>>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.
> >
> >Then fix the GPIO code properly, don't add a new panic() to the kernel.
>
> Until somebody comes up with a patch that fixes this for good I
> think that patch is still an improvement over the current situation.
> Rather than keeping the kernel running in a inconsistent state,
> which might cause all kinds of undefined behavior and which will
> lead to a crash eventually, we might as well just crash the kernel
> at the cause of the inconsistent state. This will make it obvious
> why it crashed (compared to a random stacktrace) and will also
> prevent the kernel from running in a undefined state.
>
Really, adding a panic here is not ok. With a WARN() then you have
time to save the dmesg to a file.
This CC list is way too huge. We're all wondering how often this stuff
crashes anyway? Have you tried to fix the bug instead of just calling
panic()? Is there a bugzilla entry or something? Is there a thread on
the list?
Just add a WARN() and fix the bug then cleanup the error handling.
regards,
dan carpenter
next prev parent reply other threads:[~2014-05-31 14:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-29 21:54 [PATCH] gpio: removes all usage of gpiochip_remove retval abdoulaye berthe
2014-05-29 22:14 ` David Daney
2014-05-29 23:16 ` abdoulaye berthe
2014-05-29 23:40 ` Stephen Rothwell
2014-05-30 11:30 ` [PATCH 1/2] " abdoulaye berthe
2014-05-30 11:30 ` [PATCH 2/2] gpio: gpiolib: set gpiochip_remove retval to void abdoulaye berthe
2014-05-30 11:39 ` Geert Uytterhoeven
2014-05-30 15:48 ` Ralf Baechle
2014-05-30 17:33 ` David Daney
2014-05-30 18:16 ` Lars-Peter Clausen
2014-05-30 23:29 ` Greg KH
2014-05-31 7:35 ` Lars-Peter Clausen
2014-05-31 12:19 ` Dan Carpenter [this message]
2014-06-08 23:18 ` Ben Dooks
2014-06-09 11:29 ` Lars-Peter Clausen
2014-05-29 23:25 ` [PATCH] gpio: removes all usage of gpiochip_remove retval Greg KH
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