linux-kernel - Re: [PATCH] device property: Fix the secondary firmware node handling in set_primary

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Date:   Fri, 21 Aug 2020 20:28:07 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Stable <stable@...r.kernel.org>
Subject: Re: [PATCH] device property: Fix the secondary firmware node handling
 in set_primary_fwnode()

On Fri, Aug 21, 2020 at 12:53 PM Heikki Krogerus
<heikki.krogerus@...ux.intel.com> wrote:
>
> When the primary firmware node pointer is removed from a
> device (set to NULL) the secondary firmware node pointer,
> when it exists, is made the primary node for the device.
> However, the secondary firmware node pointer of the original
> primary firmware node is never cleared (set to NULL).
>
> To avoid situation where the secondary firmware node pointer
> is pointing to a non-existing object, clearing it properly
> when the primary node is removed from a device in
> set_primary_fwnode().
>
> Fixes: 97badf873ab6 ("device property: Make it possible to use secondary firmware nodes")
> Cc: stable@...r.kernel.org
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
>  drivers/base/core.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index ac1046a382bc0..f6f620aa94086 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -4264,9 +4264,9 @@ static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
>   */
>  void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
>  {
> -       if (fwnode) {
> -               struct fwnode_handle *fn = dev->fwnode;
> +       struct fwnode_handle *fn = dev->fwnode;
>
> +       if (fwnode) {
>                 if (fwnode_is_primary(fn))
>                         fn = fn->secondary;
>
> @@ -4276,8 +4276,12 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
>                 }
>                 dev->fwnode = fwnode;
>         } else {
> -               dev->fwnode = fwnode_is_primary(dev->fwnode) ?
> -                       dev->fwnode->secondary : NULL;
> +               if (fwnode_is_primary(fn)) {
> +                       dev->fwnode = fn->secondary;
> +                       fn->secondary = NULL;
> +               } else {
> +                       dev->fwnode = NULL;
> +               }
>         }
>  }
>  EXPORT_SYMBOL_GPL(set_primary_fwnode);
> --

Applied as 5.9-rc material, thanks!