From: Arnd Bergmann <arnd@arndb.de>
To: Alexandre Courbot <acourbot@nvidia.com>
Cc: Grant Likely <grant.likely@secretlab.ca>,
Linus Walleij <linus.walleij@linaro.org>,
Guenter Roeck <linux@roeck-us.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"devicetree-discuss@lists.ozlabs.org"
<devicetree-discuss@lists.ozlabs.org>
Subject: Re: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface
Date: Wed, 9 Jan 2013 10:35:22 +0000 [thread overview]
Message-ID: <201301091035.23206.arnd@arndb.de> (raw)
In-Reply-To: <CAAVeFu+4VbCbj9TaeMm+NMDJ9_M4-j4O0ONF7Yh_un63wS38+Q@mail.gmail.com>
On Wednesday 09 January 2013, Alexandre Courbot wrote:
> On Tue, Jan 8, 2013 at 9:59 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > Please avoid the use of IS_ERR_OR_NULL(), especially on interfaces you
> > introduce yourself. AFAICT, gpiod_get cannot return NULL, so you
> > should not check for that.
>
> Sure - you sound like IS_ERR_OR_NULL() is generally considered evil,
Correct.
> may I ask why this is the case?
It's very hard to get right: either you are interested in the error code,
and then you don't have one in some cases, or you don't care but have
to check for it anyway. When you define a function, just make it clear
what the expected return values are, either NULL for error or a negative
ERR_PTR value, but not both.
Arnd
next prev parent reply other threads:[~2013-01-09 10:35 UTC|newest]
Thread overview: 53+ 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 ` [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface Alexandre Courbot
2013-01-08 7:18 ` Alexandre Courbot
2013-01-08 12:59 ` Arnd Bergmann
2013-01-09 1:06 ` Alexandre Courbot
2013-01-09 10:25 ` Russell King - ARM Linux
2013-01-09 10:35 ` Arnd Bergmann [this message]
2013-01-09 10:44 ` 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
2013-01-09 11:52 ` Arnd Bergmann
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
[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 15:26 ` 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 16:09 ` Nicolas Pitre
2013-01-09 16:21 ` Russell King - ARM Linux
2013-01-09 17:12 ` Russell King - ARM Linux
2013-01-09 17:52 ` Tony Lindgren
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 13:07 ` Arnd Bergmann
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 ` [PATCH 4/4] gpiolib: add documentation for new gpiod_ API 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 10:46 ` Arnd Bergmann
2013-01-10 4:07 ` Alex Courbot
2013-01-10 10:08 ` Arnd Bergmann
2013-01-14 10:21 ` Alex Courbot
2013-01-14 10:46 ` Arnd Bergmann
2013-01-14 10:46 ` Arnd Bergmann
2013-01-17 11:15 ` Linus Walleij
2013-01-17 11:15 ` Linus Walleij
2013-01-17 12:02 ` Greg Ungerer
2013-01-17 16:50 ` Steven King
2013-01-17 16:50 ` Steven King
2013-01-17 19:22 ` Arnd Bergmann
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
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