From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
To: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Cc: linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Linux Kernel Mailing List
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Alexandre Courbot
<acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org"
<devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org>,
Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Subject: Re: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface
Date: Wed, 9 Jan 2013 11:52:29 +0000 [thread overview]
Message-ID: <201301091152.30047.arnd@arndb.de> (raw)
In-Reply-To: <20130109111055.GG3931-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
On Wednesday 09 January 2013, Russell King - ARM Linux wrote:
> d = debugfs_create_dir("pm_debug", NULL);
> if (IS_ERR_OR_NULL(d))
> return PTR_ERR(d);
>
> Well, covered above. NULL is success here.
This one is actually worse, because in case of debugfs_create_dir,
a negative error code is documented to mean "success": The debugfs
functions intentionally return ERR_PTR(-ENODEV) when debugfs is
disabled so that any code checking for NULL pretends it is a valid
pointer, but that code is only allowed to pass this pointer into
other debugfs functions that are also stubbed out and never
dereference it.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: linux-arch@vger.kernel.org,
Linus Walleij <linus.walleij@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Grant Likely <grant.likely@secretlab.ca>,
Alexandre Courbot <acourbot@nvidia.com>,
Guenter Roeck <linux@roeck-us.net>,
"devicetree-discuss@lists.ozlabs.org"
<devicetree-discuss@lists.ozlabs.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface
Date: Wed, 9 Jan 2013 11:52:29 +0000 [thread overview]
Message-ID: <201301091152.30047.arnd@arndb.de> (raw)
Message-ID: <20130109115229.dCqQomMH8OmcWFs_kuvQnz8yhcJfU27nWagLnx04joM@z> (raw)
In-Reply-To: <20130109111055.GG3931@n2100.arm.linux.org.uk>
On Wednesday 09 January 2013, Russell King - ARM Linux wrote:
> d = debugfs_create_dir("pm_debug", NULL);
> if (IS_ERR_OR_NULL(d))
> return PTR_ERR(d);
>
> Well, covered above. NULL is success here.
This one is actually worse, because in case of debugfs_create_dir,
a negative error code is documented to mean "success": The debugfs
functions intentionally return ERR_PTR(-ENODEV) when debugfs is
disabled so that any code checking for NULL pretends it is a valid
pointer, but that code is only allowed to pass this pointer into
other debugfs functions that are also stubbed out and never
dereference it.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface
Date: Wed, 9 Jan 2013 11:52:29 +0000 [thread overview]
Message-ID: <201301091152.30047.arnd@arndb.de> (raw)
In-Reply-To: <20130109111055.GG3931@n2100.arm.linux.org.uk>
On Wednesday 09 January 2013, Russell King - ARM Linux wrote:
> d = debugfs_create_dir("pm_debug", NULL);
> if (IS_ERR_OR_NULL(d))
> return PTR_ERR(d);
>
> Well, covered above. NULL is success here.
This one is actually worse, because in case of debugfs_create_dir,
a negative error code is documented to mean "success": The debugfs
functions intentionally return ERR_PTR(-ENODEV) when debugfs is
disabled so that any code checking for NULL pretends it is a valid
pointer, but that code is only allowed to pass this pointer into
other debugfs functions that are also stubbed out and never
dereference it.
Arnd
next prev parent reply other threads:[~2013-01-09 11:52 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-08 7:18 [PATCH 0/4] gpio: introduce descriptor-based interface Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 12:59 ` Arnd Bergmann
2013-01-08 12:59 ` Arnd Bergmann
2013-01-09 1:06 ` Alexandre Courbot
2013-01-09 1:06 ` Alexandre Courbot
2013-01-09 10:25 ` Russell King - ARM Linux
2013-01-09 10:25 ` Russell King - ARM Linux
2013-01-09 10:35 ` Arnd Bergmann
2013-01-09 10:35 ` Arnd Bergmann
2013-01-09 10:44 ` Russell King - ARM Linux
2013-01-09 10:44 ` Russell King - ARM Linux
2013-01-09 11:10 ` Russell King - ARM Linux
2013-01-09 11:10 ` Russell King - ARM Linux
[not found] ` <20130109111055.GG3931-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2013-01-09 11:52 ` Arnd Bergmann [this message]
2013-01-09 11:52 ` Arnd Bergmann
2013-01-09 11:52 ` Arnd Bergmann
2013-01-09 14:44 ` Nicolas Pitre
2013-01-09 14:44 ` Nicolas Pitre
2013-01-09 15:04 ` [PATCH] Proposed removal of IS_ERR_OR_NULL() (was: Re: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface) Russell King - ARM Linux
2013-01-09 15:04 ` Russell King - ARM Linux
[not found] ` <20130109150427.GL3931-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2013-01-09 15:21 ` Grant Likely
2013-01-09 15:21 ` Grant Likely
2013-01-09 15:21 ` Grant Likely
2013-01-09 15:26 ` Arnd Bergmann
2013-01-09 15:26 ` Arnd Bergmann
2013-01-09 15:27 ` Nicolas Pitre
2013-01-09 15:27 ` Nicolas Pitre
2013-01-09 15:51 ` Russell King - ARM Linux
2013-01-09 15:51 ` Russell King - ARM Linux
2013-01-09 16:09 ` Nicolas Pitre
2013-01-09 16:09 ` Nicolas Pitre
2013-01-09 16:21 ` Russell King - ARM Linux
2013-01-09 16:21 ` Russell King - ARM Linux
2013-01-09 17:12 ` Russell King - ARM Linux
2013-01-09 17:12 ` Russell King - ARM Linux
2013-01-09 17:52 ` Tony Lindgren
2013-01-09 17:52 ` Tony Lindgren
2013-01-17 10:28 ` Linus Walleij
2013-01-17 10:28 ` Linus Walleij
2013-01-10 8:36 ` [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface Thierry Reding
2013-01-10 8:36 ` Thierry Reding
2013-01-08 7:18 ` [PATCH 2/4] gpiolib: add gpiod_get and gpiod_put functions Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 13:07 ` Arnd Bergmann
2013-01-08 13:07 ` Arnd Bergmann
2013-01-09 1:49 ` Alexandre Courbot
2013-01-09 1:49 ` Alexandre Courbot
2013-01-08 7:18 ` [PATCH 3/4] gpiolib: of: convert OF helpers to descriptor API Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` [PATCH 4/4] gpiolib: add documentation for new gpiod_ API Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 13:06 ` [PATCH 0/4] gpio: introduce descriptor-based interface Arnd Bergmann
2013-01-08 13:06 ` Arnd Bergmann
2013-01-09 1:48 ` Alexandre Courbot
2013-01-09 1:48 ` Alexandre Courbot
2013-01-09 10:46 ` Arnd Bergmann
2013-01-09 10:46 ` Arnd Bergmann
2013-01-10 4:07 ` Alex Courbot
2013-01-10 4:07 ` Alex Courbot
2013-01-10 10:08 ` Arnd Bergmann
2013-01-10 10:08 ` Arnd Bergmann
2013-01-14 10:21 ` Alex Courbot
2013-01-14 10:21 ` Alex Courbot
2013-01-14 10:21 ` Alex Courbot
2013-01-14 10:46 ` Arnd Bergmann
2013-01-14 10:46 ` Arnd Bergmann
2013-01-14 10:46 ` Arnd Bergmann
2013-01-14 10:21 ` Alex Courbot
2013-01-17 11:15 ` Linus Walleij
2013-01-17 11:15 ` Linus Walleij
2013-01-17 12:02 ` Greg Ungerer
2013-01-17 12:02 ` Greg Ungerer
2013-01-17 16:50 ` Steven King
2013-01-17 16:50 ` Steven King
2013-01-17 16:50 ` Steven King
2013-01-17 19:22 ` Arnd Bergmann
2013-01-17 19:22 ` Arnd Bergmann
2013-01-20 6:07 ` Alex Courbot
2013-01-20 6:07 ` Alex Courbot
2013-01-20 6:07 ` Alex Courbot
2013-01-22 8:55 ` Linus Walleij
2013-01-22 8:55 ` Linus Walleij
2013-01-17 11:25 ` Linus Walleij
2013-01-17 11:25 ` Linus Walleij
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