| Message ID | 20240619012356.22685-5-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | media: v4l2: Improve media link validation | expand |
Hi Laurent, Thanks for the patch. On Wed, Jun 19, 2024 at 04:23:52AM +0300, Laurent Pinchart wrote: > The v4l2_subdev_link_validate() function prints a one-time warning if it > gets called on a link whose source or sink is not a subdev. As links get > validated in the context of their sink, a call to the helper when the > link's sink is not a subdev indicates that the driver has set its > .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev > entity, which is a clear driver bug. On the other hand, the link's > source not being a subdev indicates that the helper is used for a subdev > connected to a video output device, which is a lesser issue, if only > because this is currently common practice. > > There are no drivers left in the kernel that use > v4l2_subdev_link_validate() in a context where it may get called on a > non-subdev sink. Replace the pr_warn_once() with a WARN_ON() in this > case to make sure that new offenders won't be introduced. > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > --- > drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > index 4f71199bf592..2d5e39c79620 100644 > --- a/drivers/media/v4l2-core/v4l2-subdev.c > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > @@ -1451,11 +1451,15 @@ int v4l2_subdev_link_validate(struct media_link *link) > bool states_locked; > int ret; > > - if (!is_media_entity_v4l2_subdev(link->sink->entity) || > - !is_media_entity_v4l2_subdev(link->source->entity)) { > - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > - !is_media_entity_v4l2_subdev(link->sink->entity) ? > - "sink" : "source", > + /* > + * Links are validated in the context of the sink entity. Usage of this > + * helper on a sink that is not a subdev is a clear driver bug. > + */ > + if (WARN_ON(!is_media_entity_v4l2_subdev(link->sink->entity))) > + return -EINVAL; WARN*() is nowadays deprecated. Could you continue to use pr_warn_once() for this (or dev_warn_one())? > + > + if (!is_media_entity_v4l2_subdev(link->source->entity)) { > + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > link->source->entity->name, link->source->index, > link->sink->entity->name, link->sink->index); > return 0;
On Sat, Jun 22, 2024 at 04:47:33PM +0000, Sakari Ailus wrote: > Hi Laurent, > > Thanks for the patch. > > On Wed, Jun 19, 2024 at 04:23:52AM +0300, Laurent Pinchart wrote: > > The v4l2_subdev_link_validate() function prints a one-time warning if it > > gets called on a link whose source or sink is not a subdev. As links get > > validated in the context of their sink, a call to the helper when the > > link's sink is not a subdev indicates that the driver has set its > > .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev > > entity, which is a clear driver bug. On the other hand, the link's > > source not being a subdev indicates that the helper is used for a subdev > > connected to a video output device, which is a lesser issue, if only > > because this is currently common practice. > > > > There are no drivers left in the kernel that use > > v4l2_subdev_link_validate() in a context where it may get called on a > > non-subdev sink. Replace the pr_warn_once() with a WARN_ON() in this > > case to make sure that new offenders won't be introduced. > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > > --- > > drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > > index 4f71199bf592..2d5e39c79620 100644 > > --- a/drivers/media/v4l2-core/v4l2-subdev.c > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > > @@ -1451,11 +1451,15 @@ int v4l2_subdev_link_validate(struct media_link *link) > > bool states_locked; > > int ret; > > > > - if (!is_media_entity_v4l2_subdev(link->sink->entity) || > > - !is_media_entity_v4l2_subdev(link->source->entity)) { > > - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > - !is_media_entity_v4l2_subdev(link->sink->entity) ? > > - "sink" : "source", > > + /* > > + * Links are validated in the context of the sink entity. Usage of this > > + * helper on a sink that is not a subdev is a clear driver bug. > > + */ > > + if (WARN_ON(!is_media_entity_v4l2_subdev(link->sink->entity))) > > + return -EINVAL; > > WARN*() is nowadays deprecated. Why so ? I've followed a recent discussion where some people pointed out they disliked WARN*() due to panic-on-warn, but I didn't see any conclusion there that deprecated WARN*(). > Could you continue to use pr_warn_once() > for this (or dev_warn_one())? I think a WARN_ON() is the right option here. A failure indicates a clear driver bug, we should be as loud as possible to make sure it gets noticed during development. > > + > > + if (!is_media_entity_v4l2_subdev(link->source->entity)) { > > + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > link->source->entity->name, link->source->index, > > link->sink->entity->name, link->sink->index); > > return 0;
Hi Laurent, On Tue, Jun 25, 2024 at 05:02:47PM +0300, Laurent Pinchart wrote: > On Sat, Jun 22, 2024 at 04:47:33PM +0000, Sakari Ailus wrote: > > Hi Laurent, > > > > Thanks for the patch. > > > > On Wed, Jun 19, 2024 at 04:23:52AM +0300, Laurent Pinchart wrote: > > > The v4l2_subdev_link_validate() function prints a one-time warning if it > > > gets called on a link whose source or sink is not a subdev. As links get > > > validated in the context of their sink, a call to the helper when the > > > link's sink is not a subdev indicates that the driver has set its > > > .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev > > > entity, which is a clear driver bug. On the other hand, the link's > > > source not being a subdev indicates that the helper is used for a subdev > > > connected to a video output device, which is a lesser issue, if only > > > because this is currently common practice. > > > > > > There are no drivers left in the kernel that use > > > v4l2_subdev_link_validate() in a context where it may get called on a > > > non-subdev sink. Replace the pr_warn_once() with a WARN_ON() in this > > > case to make sure that new offenders won't be introduced. > > > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > > > --- > > > drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- > > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > > > index 4f71199bf592..2d5e39c79620 100644 > > > --- a/drivers/media/v4l2-core/v4l2-subdev.c > > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > > > @@ -1451,11 +1451,15 @@ int v4l2_subdev_link_validate(struct media_link *link) > > > bool states_locked; > > > int ret; > > > > > > - if (!is_media_entity_v4l2_subdev(link->sink->entity) || > > > - !is_media_entity_v4l2_subdev(link->source->entity)) { > > > - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > > - !is_media_entity_v4l2_subdev(link->sink->entity) ? > > > - "sink" : "source", > > > + /* > > > + * Links are validated in the context of the sink entity. Usage of this > > > + * helper on a sink that is not a subdev is a clear driver bug. > > > + */ > > > + if (WARN_ON(!is_media_entity_v4l2_subdev(link->sink->entity))) > > > + return -EINVAL; > > > > WARN*() is nowadays deprecated. > > Why so ? I've followed a recent discussion where some people pointed out > they disliked WARN*() due to panic-on-warn, but I didn't see any > conclusion there that deprecated WARN*(). Fair enough, there seems to have been more discussion. As this is still user-triggerable, this should be WARN_ON_ONCE() to prevent the user from filling the logs, intentionally or not. > > > Could you continue to use pr_warn_once() > > for this (or dev_warn_one())? > > I think a WARN_ON() is the right option here. A failure indicates a > clear driver bug, we should be as loud as possible to make sure it gets > noticed during development. > > > > + > > > + if (!is_media_entity_v4l2_subdev(link->source->entity)) { > > > + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > > link->source->entity->name, link->source->index, > > > link->sink->entity->name, link->sink->index); > > > return 0; >
On Tue, Jun 25, 2024 at 03:46:06PM +0000, Sakari Ailus wrote: > Hi Laurent, > > On Tue, Jun 25, 2024 at 05:02:47PM +0300, Laurent Pinchart wrote: > > On Sat, Jun 22, 2024 at 04:47:33PM +0000, Sakari Ailus wrote: > > > Hi Laurent, > > > > > > Thanks for the patch. > > > > > > On Wed, Jun 19, 2024 at 04:23:52AM +0300, Laurent Pinchart wrote: > > > > The v4l2_subdev_link_validate() function prints a one-time warning if it > > > > gets called on a link whose source or sink is not a subdev. As links get > > > > validated in the context of their sink, a call to the helper when the > > > > link's sink is not a subdev indicates that the driver has set its > > > > .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev > > > > entity, which is a clear driver bug. On the other hand, the link's > > > > source not being a subdev indicates that the helper is used for a subdev > > > > connected to a video output device, which is a lesser issue, if only > > > > because this is currently common practice. > > > > > > > > There are no drivers left in the kernel that use > > > > v4l2_subdev_link_validate() in a context where it may get called on a > > > > non-subdev sink. Replace the pr_warn_once() with a WARN_ON() in this > > > > case to make sure that new offenders won't be introduced. > > > > > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > > > > --- > > > > drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- > > > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > > > > index 4f71199bf592..2d5e39c79620 100644 > > > > --- a/drivers/media/v4l2-core/v4l2-subdev.c > > > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > > > > @@ -1451,11 +1451,15 @@ int v4l2_subdev_link_validate(struct media_link *link) > > > > bool states_locked; > > > > int ret; > > > > > > > > - if (!is_media_entity_v4l2_subdev(link->sink->entity) || > > > > - !is_media_entity_v4l2_subdev(link->source->entity)) { > > > > - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > > > - !is_media_entity_v4l2_subdev(link->sink->entity) ? > > > > - "sink" : "source", > > > > + /* > > > > + * Links are validated in the context of the sink entity. Usage of this > > > > + * helper on a sink that is not a subdev is a clear driver bug. > > > > + */ > > > > + if (WARN_ON(!is_media_entity_v4l2_subdev(link->sink->entity))) > > > > + return -EINVAL; > > > > > > WARN*() is nowadays deprecated. > > > > Why so ? I've followed a recent discussion where some people pointed out > > they disliked WARN*() due to panic-on-warn, but I didn't see any > > conclusion there that deprecated WARN*(). > > Fair enough, there seems to have been more discussion. > > As this is still user-triggerable, this should be WARN_ON_ONCE() to prevent > the user from filling the logs, intentionally or not. It's user-triggerable, but only when the driver is clearly buggy :-) WARN_ON_ONCE() is OK with me though, I don't think warning every time would provide much added value. > > > Could you continue to use pr_warn_once() > > > for this (or dev_warn_one())? > > > > I think a WARN_ON() is the right option here. A failure indicates a > > clear driver bug, we should be as loud as possible to make sure it gets > > noticed during development. > > > > > > + > > > > + if (!is_media_entity_v4l2_subdev(link->source->entity)) { > > > > + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > > > link->source->entity->name, link->source->index, > > > > link->sink->entity->name, link->sink->index); > > > > return 0;
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c index 4f71199bf592..2d5e39c79620 100644 --- a/drivers/media/v4l2-core/v4l2-subdev.c +++ b/drivers/media/v4l2-core/v4l2-subdev.c @@ -1451,11 +1451,15 @@ int v4l2_subdev_link_validate(struct media_link *link) bool states_locked; int ret; - if (!is_media_entity_v4l2_subdev(link->sink->entity) || - !is_media_entity_v4l2_subdev(link->source->entity)) { - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", - !is_media_entity_v4l2_subdev(link->sink->entity) ? - "sink" : "source", + /* + * Links are validated in the context of the sink entity. Usage of this + * helper on a sink that is not a subdev is a clear driver bug. + */ + if (WARN_ON(!is_media_entity_v4l2_subdev(link->sink->entity))) + return -EINVAL; + + if (!is_media_entity_v4l2_subdev(link->source->entity)) { + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", link->source->entity->name, link->source->index, link->sink->entity->name, link->sink->index); return 0;
The v4l2_subdev_link_validate() function prints a one-time warning if it gets called on a link whose source or sink is not a subdev. As links get validated in the context of their sink, a call to the helper when the link's sink is not a subdev indicates that the driver has set its .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev entity, which is a clear driver bug. On the other hand, the link's source not being a subdev indicates that the helper is used for a subdev connected to a video output device, which is a lesser issue, if only because this is currently common practice. There are no drivers left in the kernel that use v4l2_subdev_link_validate() in a context where it may get called on a non-subdev sink. Replace the pr_warn_once() with a WARN_ON() in this case to make sure that new offenders won't be introduced. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> --- drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)