regression from commit b0ce9ce408b6 ("gpiolib: Do not unexport GPIO on freeing")

[Marek Behún <kabel@xxxxxxxxxx>]

Hi,

the commit b0ce9ce408b6 ("gpiolib: Do not unexport GPIO on freeing")

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b0ce9ce408b6

causes a regression on my mvebu arm board (haven't tested on other
systems), wherein if I export a GPIO to sysfs and then unexport it, it
does not disasppear from the /sys/class/gpio directory, and subsequent
writes to the export and unexport files for the gpio fail.

  $ cd /sys/class/gpio
  $ ls
  export       gpiochip0    gpiochip32   gpiochip512  unexport
  $ echo 43 >export
  $ ls
  export       gpio43       gpiochip0    gpiochip32   gpiochip512
  unexport
  $ cat gpio43/value
  1
  $ echo 43 >unexport
  $ ls
  export       gpio43       gpiochip0    gpiochip32   gpiochip512
  unexport
  $ echo 43 >unexport
  ash: write error: Invalid argument
  $ echo 43 >export
  ash: write error: Operation not permitted

Marek