Re: Patch: do not use gpiod_put on GPIOs that were not allocated with gpiod_get (fixes crash on module unload on kernel 6.6)

Hi Michael,
Thanks for the patch - applied to git.
cheers,
-Dave

On Sun, 14 Jul 2024 at 19:05, Michael Schwingen <[email protected]>
wrote:

>
> Hi,
>
> I noticed crashes when unloading the gpib_bitbang module after upgrading my
> development raspberry pi to kernel 6.6.  I traced them to the use of
> gpiod_put on GPIO objects that were not allocated using gpiod_get, which
> according to the ernel documentation should not be done.
>
> The attached patch fixes the problem for me.
>
> cu
> Michael Schwingen
>
>
>
> From cb23c0aa14effc437041c39eb24178ca5f11e74c Mon Sep 17 00:00:00 2001
> From: Michael Schwingen <[email protected]>
> Date: Fri, 12 Jul 2024 16:35:08 +0200
> Subject: [PATCH 1/2] do not use gpiod_put on GPIOs that were not allocated
>  with gpiod_get (fixes crash on module unload on kernel 6.6)
>
> ---
>  linux-gpib-kernel/drivers/gpib/gpio/gpib_bitbang.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/linux-gpib-kernel/drivers/gpib/gpio/gpib_bitbang.c
> b/linux-gpib-kernel/drivers/gpib/gpio/gpib_bitbang.c
> index 5d5a2690..7aebf119 100644
> --- a/linux-gpib-kernel/drivers/gpib/gpio/gpib_bitbang.c
> +++ b/linux-gpib-kernel/drivers/gpib/gpio/gpib_bitbang.c
> @@ -971,7 +971,6 @@ static int allocate_gpios(void) {
>          if ( j != last) {                    /* error - undo what already
> done */
>                  dbg_printk (0, "request for gpios failed at %d.\n", j);
>                  while (j) {
> -                        gpiod_put(all_descriptors[--j]);
>                          all_descriptors[j] = 0;
>                          gpio_free (gpios_vector[j]+gpio_offset);
>                  }
> @@ -985,7 +984,6 @@ static void release_gpios(void) {
>          int j = sn7516x ? GPIB_PINS + SN7516X_PINS : GPIB_PINS ;
>          while (j) {
>                  if (all_descriptors[--j]) {
> -                        gpiod_put(all_descriptors[j]);
>                          all_descriptors[j] = 0;
>                          gpio_free (gpios_vector[j]+gpio_offset);
>                  }
> @@ -1144,7 +1142,6 @@ static int __init bb_init_module(void)
>  static void __exit bb_exit_module(void)
>  {
>         gpiod_direction_input(ACT_LED);
> -        gpiod_put(ACT_LED);
>
>          dbg_printk(1,"%s\n", "module unloaded!");
>
> --
> 2.39.2
>
>
>
>
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