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>
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.
*/
- 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,
Laurent Pinchart
