Re: [PATCH v1 2/2] device property: Don't clear secondary pointer for shared primary firmware node

[Ferry Toth]

Hi

Op 23-10-2020 om 14:35 schreef Heikki Krogerus:
> 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>

Tested-by: Ferry Toth <fntoth@xxxxxxxxx>

> > ---
> >   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