From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
To: Kent Gibson <warthog618@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-gpio <linux-gpio@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH v7 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL
Date: Wed, 9 Sep 2020 11:41:35 +0200 [thread overview]
Message-ID: <CAMpxmJVU9ZniBjFSuhYYaDLUX1jeYeEjYJzdoy06J24SiVNn3w@mail.gmail.com> (raw)
In-Reply-To: <20200909093523.GA1506132@sol>
On Wed, Sep 9, 2020 at 11:35 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> On Wed, Sep 09, 2020 at 11:26:00AM +0200, Bartosz Golaszewski wrote:
> > On Wed, Sep 9, 2020 at 11:24 AM Kent Gibson <warthog618@gmail.com> wrote:
> > >
> > > On Sat, Sep 05, 2020 at 09:35:36PM +0800, Kent Gibson wrote:
> > > > Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> > > > returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
> > > >
> > > > The struct linereq implementation is based on the v1 struct linehandle
> > > > implementation.
> > > >
> > > > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > > > ---
> > > >
> > >
> > > [snip]
> > >
> > > > if (copy_from_user(&offset, ip, sizeof(offset)))
> > > > return -EFAULT;
> > > > @@ -1104,6 +1505,25 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
> > > > MAJOR(devt), gdev->id);
> > > >
> > > > return 0;
> > > > + /*
> > > > + * array sizes must ensure 64-bit alignment and not create holes in
> > > > + * the struct packing.
> > > > + */
> > > > + BUILD_BUG_ON(IS_ALIGNED(GPIO_V2_LINES_MAX, 2));
> > > > + BUILD_BUG_ON(IS_ALIGNED(GPIO_MAX_NAME_SIZE, 8));
> > > > +
> > > > + /*
> > > > + * check that uAPI structs are 64-bit aligned for 32/64-bit
> > > > + * compatibility
> > > > + */
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_attribute), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_config_attribute), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_config), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_request), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_info), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_info_changed), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_event), 8));
> > > > + BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_values), 8));
> > > > }
> > > >
> > >
> > > A couple of things here - these should all be !IS_ALIGNED.
> > > And the BUILD_BUG_ON gets compiled out, and so doesn't fail, if they are
> > > after the return.
> > >
> > > How would you like that fixed - v8 or a patch once v7 is in?
> > >
> > > Cheers,
> > > Kent.
> >
> > v8 please. Why is it compiled out though? Does it need some config option?
> >
>
> Not sure - haven't looked into it. I only noticed the condition was
> inverted in passing, and when I flipped it it still compiled.
> Moving the return to the end of the function made them all fail,
> as they should if IS_ALIGNED is true.
>
> Having BUILD_BUG_ON being able to compile out quietly is a problem in
> itself. Nothing special in my setup that I am aware of.
>
> Cheers,
> Kent.
From include/linux/compiler_types.h:
295 #ifdef __OPTIMIZE__
296 # define __compiletime_assert(condition, msg, prefix, suffix) \
297 do { \
298 extern void prefix ## suffix(void)
__compiletime_error(msg); \
299 if (!(condition)) \
300 prefix ## suffix(); \
301 } while (0)
302 #else
303 # define __compiletime_assert(condition, msg, prefix, suffix) do {
} while (0)
304 #endif
__OPTIMIZE__ is a predefined macro. I'm not sure about your setup but
it it's defined for me in all my yocto SDK builds and BUILD_BUG_ON(1)
fails as expected.
Bartosz
next prev parent reply other threads:[~2020-09-09 9:41 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-05 13:35 [PATCH v7 00/20] gpio: cdev: add uAPI v2 Kent Gibson
2020-09-05 13:35 ` [PATCH v7 01/20] gpiolib: cdev: desc_to_lineinfo should set info offset Kent Gibson
2020-09-05 13:35 ` [PATCH v7 02/20] gpiolib: cdev: replace strncpy with strscpy Kent Gibson
2020-09-05 13:35 ` [PATCH v7 03/20] gpio: uapi: define GPIO_MAX_NAME_SIZE for array sizes Kent Gibson
2020-09-05 13:35 ` [PATCH v7 04/20] gpio: uapi: define uAPI v2 Kent Gibson
2020-09-05 13:35 ` [PATCH v7 05/20] gpiolib: make cdev a build option Kent Gibson
2020-09-05 13:35 ` [PATCH v7 06/20] gpiolib: add build option for CDEV v1 ABI Kent Gibson
2020-09-05 13:35 ` [PATCH v7 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL Kent Gibson
2020-09-09 9:24 ` Kent Gibson
2020-09-09 9:26 ` Bartosz Golaszewski
2020-09-09 9:35 ` Kent Gibson
2020-09-09 9:41 ` Bartosz Golaszewski [this message]
2020-09-09 9:49 ` Kent Gibson
2020-09-09 9:54 ` Bartosz Golaszewski
2020-09-15 10:31 ` Andy Shevchenko
2020-09-20 11:12 ` Kent Gibson
2020-09-24 13:36 ` Bartosz Golaszewski
2020-09-24 13:40 ` Kent Gibson
2020-09-05 13:35 ` [PATCH v7 08/20] gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL Kent Gibson
2020-09-05 13:35 ` [PATCH v7 09/20] gpiolib: cdev: support edge detection for uAPI v2 Kent Gibson
2020-09-05 13:35 ` [PATCH v7 10/20] gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL Kent Gibson
2020-09-05 13:35 ` [PATCH v7 11/20] gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL Kent Gibson
2020-09-05 13:35 ` [PATCH v7 12/20] gpiolib: cdev: support setting debounce Kent Gibson
2020-09-05 13:35 ` [PATCH v7 13/20] gpio: uapi: document uAPI v1 as deprecated Kent Gibson
2020-09-05 13:35 ` [PATCH v7 14/20] tools: gpio: port lsgpio to v2 uAPI Kent Gibson
2020-09-05 13:35 ` [PATCH v7 15/20] tools: gpio: port gpio-watch " Kent Gibson
2020-09-05 13:35 ` [PATCH v7 16/20] tools: gpio: rename nlines to num_lines Kent Gibson
2020-09-05 13:35 ` [PATCH v7 17/20] tools: gpio: port gpio-hammer to v2 uAPI Kent Gibson
2020-09-05 13:35 ` [PATCH v7 18/20] tools: gpio: port gpio-event-mon " Kent Gibson
2020-09-05 13:35 ` [PATCH v7 19/20] tools: gpio: add multi-line monitoring to gpio-event-mon Kent Gibson
2020-09-05 13:35 ` [PATCH v7 20/20] tools: gpio: add debounce support " Kent Gibson
2020-09-08 16:07 ` [PATCH v7 00/20] gpio: cdev: add uAPI v2 Bartosz Golaszewski
2020-09-09 1:16 ` Kent Gibson
2020-09-09 7:52 ` Bartosz Golaszewski
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