[v1,04/16] thunderbolt: ACPI: Use acpi_find_child_by_adr()

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Instead of walking the list of children of an ACPI device directly
in order to find the child matching a given bus address, use
acpi_find_child_by_adr() for this purpose.

Apart from simplifying the code, 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).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/thunderbolt/acpi.c |    9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

On Thu, Jun 09, 2022 at 03:54:40PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Instead of walking the list of children of an ACPI device directly
> in order to find the child matching a given bus address, use
> acpi_find_child_by_adr() for this purpose.
> 
> Apart from simplifying the code, 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).
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/thunderbolt/acpi.c |    9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> Index: linux-pm/drivers/thunderbolt/acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/thunderbolt/acpi.c
> +++ linux-pm/drivers/thunderbolt/acpi.c
> @@ -304,8 +304,6 @@ static bool tb_acpi_bus_match(struct dev
>  static struct acpi_device *tb_acpi_find_port(struct acpi_device *adev,
>  					     const struct tb_port *port)
>  {
> -	struct acpi_device *port_adev;
> -
>  	if (!adev)
>  		return NULL;
>  
> @@ -313,12 +311,7 @@ static struct acpi_device *tb_acpi_find_
>  	 * Device routers exists under the downstream facing USB4 port
>  	 * of the parent router. Their _ADR is always 0.
>  	 */
> -	list_for_each_entry(port_adev, &adev->children, node) {
> -		if (acpi_device_adr(port_adev) == port->port)
> -			return port_adev;
> -	}
> -
> -	return NULL;
> +	return acpi_find_child_by_adr(adev, port->port);
>  }
>  
>  static struct acpi_device *tb_acpi_switch_find_companion(struct tb_switch *sw)

I don't think you need tb_acpi_find_port() anymore. You can just call
acpi_find_child_by_ard(ACPI_COMPANION(...), port->port) directly, no?

thanks,

On Fri, Jun 10, 2022 at 8:46 AM Heikki Krogerus
<heikki.krogerus@linux.intel.com> wrote:
>
> On Thu, Jun 09, 2022 at 03:54:40PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Instead of walking the list of children of an ACPI device directly
> > in order to find the child matching a given bus address, use
> > acpi_find_child_by_adr() for this purpose.
> >
> > Apart from simplifying the code, 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).
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >  drivers/thunderbolt/acpi.c |    9 +--------
> >  1 file changed, 1 insertion(+), 8 deletions(-)
> >
> > Index: linux-pm/drivers/thunderbolt/acpi.c
> > ===================================================================
> > --- linux-pm.orig/drivers/thunderbolt/acpi.c
> > +++ linux-pm/drivers/thunderbolt/acpi.c
> > @@ -304,8 +304,6 @@ static bool tb_acpi_bus_match(struct dev
> >  static struct acpi_device *tb_acpi_find_port(struct acpi_device *adev,
> >                                            const struct tb_port *port)
> >  {
> > -     struct acpi_device *port_adev;
> > -
> >       if (!adev)
> >               return NULL;
> >
> > @@ -313,12 +311,7 @@ static struct acpi_device *tb_acpi_find_
> >        * Device routers exists under the downstream facing USB4 port
> >        * of the parent router. Their _ADR is always 0.
> >        */
> > -     list_for_each_entry(port_adev, &adev->children, node) {
> > -             if (acpi_device_adr(port_adev) == port->port)
> > -                     return port_adev;
> > -     }
> > -
> > -     return NULL;
> > +     return acpi_find_child_by_adr(adev, port->port);
> >  }
> >
> >  static struct acpi_device *tb_acpi_switch_find_companion(struct tb_switch *sw)
>
> I don't think you need tb_acpi_find_port() anymore. You can just call
> acpi_find_child_by_ard(ACPI_COMPANION(...), port->port) directly, no?

Technically I can, but I thought that the comment in
tb_acpi_find_port() was worth retaining.