Hi Laurent,
On Tue, Apr 02, 2024 at 02:41:05AM +0300, Laurent Pinchart wrote:
> On Wed, Mar 20, 2024 at 03:55:58AM +0200, Laurent Pinchart wrote:
> > Hi Sakari,
> >
> > Thank you for the patch.
> >
> > On Wed, Mar 13, 2024 at 09:24:55AM +0200, Sakari Ailus wrote:
> > > Add trivial S_ROUTING IOCTL support for drivers where routing is static.
> > > Essentially this means returning the same information G_ROUTING call would
> > > have done.
> > >
> > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> >
> > Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
>
> Actually...
>
> > > ---
> > > drivers/media/v4l2-core/v4l2-subdev.c | 14 ++++++++++++++
> > > 1 file changed, 14 insertions(+)
> > >
> > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > > index a6107e440ef0..c8c435df92c8 100644
> > > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > > @@ -930,6 +930,20 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
> > >
> > > memset(routing->reserved, 0, sizeof(routing->reserved));
> > >
> > > + /*
> > > + * If the driver doesn't support setting routing, just return
> > > + * the routing table here.
> > > + */
> > > + if (!v4l2_subdev_has_op(sd, pad, set_routing)) {
> > > + memcpy((struct v4l2_subdev_route *)(uintptr_t)routing->routes,
> > > + state->routing.routes,
> > > + min(state->routing.num_routes, routing->len_routes) *
> > > + sizeof(*state->routing.routes));
> > > + routing->num_routes = state->routing.num_routes;
> > > +
> > > + return 0;
> > > + }
> > > +
>
> I think this should be done after the next code block that validates the
> arguments. Otherwise the S_ROUTING ioctl will behave differently with
> regard to blatantly invalid arguments, depending on whether or not the
> subdev implements the .set_routing() operation. This can confuse
> userspace, and does confuse v4l2-compliance.
>
> I have the following change in my tree that fixes the problem, feel free
> to squash it with this patch in v9.
>
> commit 1e1f03eb8bc118c53a9deab05063d71a2fe7aa5f
> Author: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Date: Tue Apr 2 02:06:01 2024 +0300
>
> fixup! media: v4l: subdev: Add trivial set_routing support
>
> Validate arguments before handling the trivial set_routing support to
> expose a consistent behaviour to userspace. This fixes an issue with
> v4l2-compliance.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Thanks, I'll squash this into the patch.
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index def91ab32c07..129867ed2bad 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -933,19 +933,12 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
> memset(routing->reserved, 0, sizeof(routing->reserved));
>
> /*
> - * If the driver doesn't support setting routing, just return
> - * the routing table here.
> + * Perform argument validation first, or subdevs that don't
> + * support setting routing will not return an error when
> + * arguments are blatantly wrong. The difference in behaviour
> + * could be confusing for userspace, and in particular for API
> + * compliance checkers.
This is more fit for development time discussion, not something that should
be left in the code IMO.
> */
> - if (!v4l2_subdev_has_op(sd, pad, set_routing)) {
> - memcpy((struct v4l2_subdev_route *)(uintptr_t)routing->routes,
> - state->routing.routes,
> - min(state->routing.num_routes, routing->len_routes) *
> - sizeof(*state->routing.routes));
> - routing->num_routes = state->routing.num_routes;
> -
> - return 0;
> - }
> -
> for (i = 0; i < routing->num_routes; ++i) {
> const struct v4l2_subdev_route *route = &routes[i];
> const struct media_pad *pads = sd->entity.pads;
> @@ -969,6 +962,20 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
> return -EINVAL;
> }
>
> + /*
> + * If the driver doesn't support setting routing, just return
> + * the routing table here.
> + */
> + if (!v4l2_subdev_has_op(sd, pad, set_routing)) {
> + memcpy((struct v4l2_subdev_route *)(uintptr_t)routing->routes,
> + state->routing.routes,
> + min(state->routing.num_routes, routing->len_routes) *
> + sizeof(*state->routing.routes));
> + routing->num_routes = state->routing.num_routes;
> +
> + return 0;
> + }
> +
> krouting.num_routes = routing->num_routes;
> krouting.len_routes = routing->len_routes;
> krouting.routes = routes;
>
>
> > > for (i = 0; i < routing->num_routes; ++i) {
> > > const struct v4l2_subdev_route *route = &routes[i];
> > > const struct media_pad *pads = sd->entity.pads;
>
--
Regards,
Sakari Ailus
