On Thu, Oct 22, 2020 at 09:41:00PM +0300, Andy Shevchenko wrote:
> It appears that firmware nodes can be shared between devices. In such case
> when a (child) device is about to be deleted, its firmware node may be shared
> and ACPI_COMPANION_SET(..., NULL) call for it breaks the secondary link
> of the shared primary firmware node.
>
> In order to prevent that, check, if the device has a parent and parent's
> firmware node is shared with its child, and avoid crashing the link.
>
> Fixes: c15e1bdda436 ("device property: Fix the secondary firmware node handling in set_primary_fwnode()")
> Reported-by: Ferry Toth <fntoth@xxxxxxxxx>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
FWIW:
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> drivers/base/core.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 41feab679fa1..78114ddac755 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -4264,6 +4264,7 @@ static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
> */
> void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
> {
> + struct device *parent = dev->parent;
> struct fwnode_handle *fn = dev->fwnode;
>
> if (fwnode) {
> @@ -4278,7 +4279,8 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
> } else {
> if (fwnode_is_primary(fn)) {
> dev->fwnode = fn->secondary;
> - fn->secondary = ERR_PTR(-ENODEV);
> + if (!(parent && fn == parent->fwnode))
> + fn->secondary = ERR_PTR(-ENODEV);
> } else {
> dev->fwnode = NULL;
> }
> --
> 2.28.0
--
heikki
