From: Grant Likely <grant.likely@secretlab.ca>
To: Linus Walleij <linus.walleij@linaro.org>,
Alexandre Courbot <acourbot@nvidia.com>
Cc: linux-arch@vger.kernel.org, gnurou@gmail.com,
linux-arm-kernel@lists.infradead.org,
Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/9] gpiolib: use gpio_chips list in sysfs ops
Date: Sat, 09 Feb 2013 09:37:53 +0000 [thread overview]
Message-ID: <20130209093753.654C53E2C59@localhost> (raw)
In-Reply-To: <CACRpkdaC3pu3tBZrw0Az226XEt6+AzJ_NiiCaLwV9o6NUZ8MQw@mail.gmail.com>
On Tue, 5 Feb 2013 18:15:54 +0100, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Sat, Feb 2, 2013 at 5:29 PM, Alexandre Courbot <acourbot@nvidia.com> wrote:
>
> > This makes the code both simpler and faster compared to parsing the GPIO
> > number space.
> >
> > Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Applied, thanks.
However, this code is incorrect (it was incorrect before you touched it,
so not your fault). Moving it to a list makes it a lot worse though
because it introduces the possibility of dereferencing an invalid
pointer. The hooks need to grab the spinlock before parsing the list.
I've got a patch which I'll post. I'd appreciate it if you can test
also.
In actual fact, I'd like to replace the spinlock with a mutex, but that
requires some auditing to make sure there aren't any users from an
atomic context.
g.
WARNING: multiple messages have this Message-ID (diff)
From: Grant Likely <grant.likely@secretlab.ca>
To: Linus Walleij <linus.walleij@linaro.org>,
Alexandre Courbot <acourbot@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, gnurou@gmail.com
Subject: Re: [PATCH 4/9] gpiolib: use gpio_chips list in sysfs ops
Date: Sat, 09 Feb 2013 09:37:53 +0000 [thread overview]
Message-ID: <20130209093753.654C53E2C59@localhost> (raw)
Message-ID: <20130209093753.IfnKHG3X77onfVUNmBQ_7C3capQSWS1dUWjrGGBspmc@z> (raw)
In-Reply-To: <CACRpkdaC3pu3tBZrw0Az226XEt6+AzJ_NiiCaLwV9o6NUZ8MQw@mail.gmail.com>
On Tue, 5 Feb 2013 18:15:54 +0100, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Sat, Feb 2, 2013 at 5:29 PM, Alexandre Courbot <acourbot@nvidia.com> wrote:
>
> > This makes the code both simpler and faster compared to parsing the GPIO
> > number space.
> >
> > Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Applied, thanks.
However, this code is incorrect (it was incorrect before you touched it,
so not your fault). Moving it to a list makes it a lot worse though
because it introduces the possibility of dereferencing an invalid
pointer. The hooks need to grab the spinlock before parsing the list.
I've got a patch which I'll post. I'd appreciate it if you can test
also.
In actual fact, I'd like to replace the spinlock with a mutex, but that
requires some auditing to make sure there aren't any users from an
atomic context.
g.
WARNING: multiple messages have this Message-ID (diff)
From: grant.likely@secretlab.ca (Grant Likely)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 4/9] gpiolib: use gpio_chips list in sysfs ops
Date: Sat, 09 Feb 2013 09:37:53 +0000 [thread overview]
Message-ID: <20130209093753.654C53E2C59@localhost> (raw)
In-Reply-To: <CACRpkdaC3pu3tBZrw0Az226XEt6+AzJ_NiiCaLwV9o6NUZ8MQw@mail.gmail.com>
On Tue, 5 Feb 2013 18:15:54 +0100, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Sat, Feb 2, 2013 at 5:29 PM, Alexandre Courbot <acourbot@nvidia.com> wrote:
>
> > This makes the code both simpler and faster compared to parsing the GPIO
> > number space.
> >
> > Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Applied, thanks.
However, this code is incorrect (it was incorrect before you touched it,
so not your fault). Moving it to a list makes it a lot worse though
because it introduces the possibility of dereferencing an invalid
pointer. The hooks need to grab the spinlock before parsing the list.
I've got a patch which I'll post. I'd appreciate it if you can test
also.
In actual fact, I'd like to replace the spinlock with a mutex, but that
requires some auditing to make sure there aren't any users from an
atomic context.
g.
next prev parent reply other threads:[~2013-02-09 9:37 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-02 16:29 [PATCH 0/9] gpiolib: remove gpio_desc[] static array Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` [PATCH 1/9] gpiolib: link all gpio_chips using a list Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:00 ` Linus Walleij
2013-02-05 17:00 ` Linus Walleij
2013-02-09 9:20 ` Grant Likely
2013-02-09 9:20 ` Grant Likely
2013-02-02 16:29 ` [PATCH 2/9] gpiolib: use gpio_chips list in gpiolib_sysfs_init Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:04 ` Linus Walleij
2013-02-05 17:04 ` Linus Walleij
2013-02-09 9:22 ` Grant Likely
2013-02-09 9:22 ` Grant Likely
2013-02-09 9:22 ` Grant Likely
2013-02-02 16:29 ` [PATCH 3/9] gpiolib: use gpio_chips list in gpiochip_find Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:05 ` Linus Walleij
2013-02-05 17:05 ` Linus Walleij
2013-02-09 9:25 ` Grant Likely
2013-02-09 9:25 ` Grant Likely
2013-02-09 9:25 ` Grant Likely
2013-02-02 16:29 ` [PATCH 4/9] gpiolib: use gpio_chips list in sysfs ops Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:15 ` Linus Walleij
2013-02-05 17:15 ` Linus Walleij
2013-02-09 9:37 ` Grant Likely [this message]
2013-02-09 9:37 ` Grant Likely
2013-02-09 9:37 ` Grant Likely
2013-02-09 13:53 ` Alexandre Courbot
2013-02-09 13:53 ` Alexandre Courbot
2013-02-02 16:29 ` [PATCH 5/9] gpiolib: use gpio_chips list in gpiochip_find_base Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:21 ` Linus Walleij
2013-02-05 17:21 ` Linus Walleij
2013-02-06 4:48 ` Alex Courbot
2013-02-06 4:48 ` Alex Courbot
2013-02-09 9:47 ` Grant Likely
2013-02-09 9:47 ` Grant Likely
2013-02-02 16:29 ` [PATCH 6/9] gpiolib: use descriptors internally Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 17:53 ` Linus Walleij
2013-02-05 17:53 ` Linus Walleij
2013-02-07 6:57 ` Alexandre Courbot
2013-02-07 6:57 ` Alexandre Courbot
2013-02-09 9:17 ` Grant Likely
2013-02-09 9:17 ` Grant Likely
2013-02-09 9:17 ` Grant Likely
2013-02-11 14:09 ` Linus Walleij
2013-02-11 14:09 ` Linus Walleij
2013-02-11 15:40 ` Paul Mundt
2013-02-11 15:40 ` Paul Mundt
2013-02-11 17:39 ` Stephen Warren
2013-02-11 17:39 ` Stephen Warren
2013-02-12 12:29 ` Linus Walleij
2013-02-12 12:29 ` Linus Walleij
2013-02-12 15:59 ` Paul Mundt
2013-02-12 15:59 ` Paul Mundt
2013-02-12 17:18 ` Arnd Bergmann
2013-02-12 17:18 ` Arnd Bergmann
2013-02-09 13:11 ` Grant Likely
2013-02-09 13:11 ` Grant Likely
2013-02-09 13:11 ` Grant Likely
2013-02-09 13:11 ` Grant Likely
2013-02-09 14:15 ` Alexandre Courbot
2013-02-09 14:15 ` Alexandre Courbot
2013-02-09 13:24 ` Grant Likely
2013-02-09 13:24 ` Grant Likely
2013-02-09 13:24 ` Grant Likely
2013-02-09 13:24 ` Grant Likely
2013-02-09 14:18 ` Alexandre Courbot
2013-02-09 14:18 ` Alexandre Courbot
2013-02-02 16:29 ` [PATCH 7/9] gpiolib: let gpio_chip reference its descriptors Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 18:00 ` Linus Walleij
2013-02-05 18:00 ` Linus Walleij
2013-02-09 13:28 ` Grant Likely
2013-02-09 13:28 ` Grant Likely
2013-02-02 16:29 ` [PATCH 8/9] gpiolib: use gpio_chips list in gpio_to_desc Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 18:01 ` Linus Walleij
2013-02-05 18:01 ` Linus Walleij
2013-02-05 18:01 ` Linus Walleij
2013-02-09 9:58 ` Grant Likely
2013-02-09 9:58 ` Grant Likely
2013-02-09 9:58 ` Grant Likely
2013-02-09 9:58 ` Grant Likely
2013-02-09 14:21 ` Alexandre Courbot
2013-02-09 14:21 ` Alexandre Courbot
2013-02-09 14:37 ` Grant Likely
2013-02-09 14:37 ` Grant Likely
2013-02-02 16:29 ` [PATCH 9/9] gpiolib: dynamically allocate descriptors array Alexandre Courbot
2013-02-02 16:29 ` Alexandre Courbot
2013-02-05 18:02 ` Linus Walleij
2013-02-05 18:02 ` Linus Walleij
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