gpio: virtuser: Use GPIO_LOOKUP_IDX() macro

Use GPIO_LOOKUP_IDX() macro which provides a compound literal
and can be used with dynamic data.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.

gpio: virtuser: Use GPIO_LOOKUP_IDX() macro

Use GPIO_LOOKUP_IDX() macro which provides a compound literal
and can be used with dynamic data.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240820200858.3659995-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

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gpio: virtuser: avoid non-constant format string

Using a string variable as an sprintf format is potentially
dangerous, and gcc can warn about this:

drivers/gpio/gpio-virtuser.c: In function 'gpio_

gpio: virtuser: avoid non-constant format string

Using a string variable as an sprintf format is potentially
dangerous, and gcc can warn about this:

drivers/gpio/gpio-virtuser.c: In function 'gpio_virtuser_dbgfs_init_line_attrs':
drivers/gpio/gpio-virtuser.c:808:9: error: format not a string literal and no format arguments [-Werror=format-security]
808 | sprintf(data->consumer, id);
| ^~~~~~~

Change it to a simpler strscpy() instead to just copy it and check
the destination buffer size.

Fixes: 91581c4b3f29 ("gpio: virtuser: new virtual testing driver for the GPIO API")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240719144422.2082394-1-arnd@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

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gpio: virtuser: actually use the "trimmed" local variable

This variable is set with the intention of being passed to the
subsequent strcmp() but something went wrong and it was left unused. Use
it n

gpio: virtuser: actually use the "trimmed" local variable

This variable is set with the intention of being passed to the
subsequent strcmp() but something went wrong and it was left unused. Use
it now.

Fixes: 91581c4b3f29 ("gpio: virtuser: new virtual testing driver for the GPIO API")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407092245.BPnW2mr6-lkp@intel.com/
Link: https://lore.kernel.org/r/20240709151235.90523-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

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gpio: virtuser: new virtual testing driver for the GPIO API

The GPIO subsystem used to have a serious problem with undefined behavior
and use-after-free bugs on hot-unplug of GPIO chips. This can be

gpio: virtuser: new virtual testing driver for the GPIO API

The GPIO subsystem used to have a serious problem with undefined behavior
and use-after-free bugs on hot-unplug of GPIO chips. This can be
considered a corner-case by some as most GPIO controllers are enabled
early in the boot process and live until the system goes down but most
GPIO drivers do allow unbind over sysfs, many are loadable modules that
can be (force) unloaded and there are also GPIO devices that can be
dynamically detached, for instance CP2112 which is a USB GPIO expender.

Bugs can be triggered both from user-space as well as by in-kernel users.
We have the means of testing it from user-space via the character device
but the issues manifest themselves differently in the kernel.

This is a proposition of adding a new virtual driver - a configurable
GPIO consumer that can be configured over configfs (similarly to
gpio-sim) or described on the device-tree.

This driver is aimed as a helper in spotting any regressions in
hot-unplug handling in GPIOLIB.

Link: https://lore.kernel.org/r/20240708142912.120570-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

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