linux-kernel - Re: [PATCH] iio: core: fix ioctl handlers removal

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Message-ID: <CA+U=DsqQUse-cP7k+42reHPYfbAUMTsqLst5--BHKg53FhNbxg@mail.gmail.com>
Date:   Fri, 23 Apr 2021 10:17:42 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Tomasz Duszynski <tomasz.duszynski@...akon.com>
Cc:     linux-iio <linux-iio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>
Subject: Re: [PATCH] iio: core: fix ioctl handlers removal

On Thu, Apr 22, 2021 at 11:26 PM Tomasz Duszynski
<tomasz.duszynski@...akon.com> wrote:
>
> Currently ioctl handlers are removed twice. For the first time during
> iio_device_unregister() then later on inside
> iio_device_unregister_eventset() and iio_buffers_free_sysfs_and_mask().
> Double free leads to kernel panic.
>
> Fix this by not touching ioctl handlers list directly but rather
> letting code responsible for registration call the matching cleanup
> routine itself.
>

This change is missing this tag:

Fixes: 8dedcc3eee3ac ("iio: core: centralize ioctl() calls to the main chardev")

With that tag added:
Acked-by: Alexandru Ardelean <ardeleanalex@...il.com>

Apologies for the breakage.
Also, I wasn't sure if Jonathan or anyone else wanted to do this change.

Thanks for the patch
Alex

> Signed-off-by: Tomasz Duszynski <tomasz.duszynski@...akon.com>
> ---
>  drivers/iio/industrialio-core.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index d92c58a94fe4..98944cfc7331 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1939,9 +1939,6 @@ void iio_device_unregister(struct iio_dev *indio_dev)
>
>         indio_dev->info = NULL;
>
> -       list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry)
> -               list_del(&h->entry);
> -
>         iio_device_wakeup_eventset(indio_dev);
>         iio_buffer_wakeup_poll(indio_dev);
>
> --
> 2.31.1
>