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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Thu, 30 Jun 2022 14:48:02 +0200
Message-ID: <CAJZ5v0jNOsAXSuX9dw9N3w12Y_nq62Z=OL4QQTwH=OnReGpQvA@mail.gmail.com>
Subject: Re: [PATCH v2] hisi_lpc: Use acpi_dev_for_each_child()
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc:     Linux ACPI <linux-acpi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        John Garry <john.garry@huawei.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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On Wed, Jun 29, 2022 at 3:47 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Instead of walking the list of children of an ACPI device directly,
> use acpi_dev_for_each_child() to carry out an action for all of
> the given ACPI device's children.
>
> This will help to eliminate the children list head from struct
> acpi_device as it is redundant and it is used in questionable ways
> in some places (in particular, locking is needed for walking the
> list pointed to it safely, but it is often missing).

I've overlooked another usage of the children list in hisi_lpc, in
hisi_lpc_acpi_probe(), and eliminating that one is a bit more
complicated.

So please scratch this one and I will send a v3 when 0-day tells me
that it builds.

> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Acked-by: John Garry <john.garry@huawei.com>
> ---
>
> -> v2:
>    * Drop unused local variable (John).
>    * Add ACK from John.
>
> ---
>  drivers/bus/hisi_lpc.c |   14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> Index: linux-pm/drivers/bus/hisi_lpc.c
> ===================================================================
> --- linux-pm.orig/drivers/bus/hisi_lpc.c
> +++ linux-pm/drivers/bus/hisi_lpc.c
> @@ -471,6 +471,12 @@ static int hisi_lpc_acpi_remove_subdev(s
>         return 0;
>  }
>
> +static int hisi_lpc_acpi_clear_enumerated(struct acpi_device *adev, void *not_used)
> +{
> +       acpi_device_clear_enumerated(adev);
> +       return 0;
> +}
> +
>  struct hisi_lpc_acpi_cell {
>         const char *hid;
>         const char *name;
> @@ -480,13 +486,9 @@ struct hisi_lpc_acpi_cell {
>
>  static void hisi_lpc_acpi_remove(struct device *hostdev)
>  {
> -       struct acpi_device *adev = ACPI_COMPANION(hostdev);
> -       struct acpi_device *child;
> -
>         device_for_each_child(hostdev, NULL, hisi_lpc_acpi_remove_subdev);
> -
> -       list_for_each_entry(child, &adev->children, node)
> -               acpi_device_clear_enumerated(child);
> +       acpi_dev_for_each_child(ACPI_COMPANION(hostdev),
> +                               hisi_lpc_acpi_clear_enumerated, NULL);
>  }
>
>  /*
>
>
>