From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: linux-media@vger.kernel.org, sakari.ailus@linux.intel.com,
Jacopo Mondi <jacopo+renesas@jmondi.org>,
niklas.soderlund+renesas@ragnatech.se,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Pratyush Yadav <p.yadav@ti.com>
Subject: Re: [PATCH v2 4/6] media: subdev: add subdev state locking
Date: Tue, 21 Dec 2021 10:11:11 +0200 [thread overview]
Message-ID: <YcGMH2icrC3aCjZz@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20211217135022.364954-5-tomi.valkeinen@ideasonboard.com>
Hi Tomi,
Thank you for the patch.
On Fri, Dec 17, 2021 at 03:50:20PM +0200, Tomi Valkeinen wrote:
> The V4L2 subdevs have managed without centralized locking for the state
> (previously pad_config), as the try-state is supposedly safe (although I
> believe two TRY ioctls for the same fd would race), and the
> active-state, and its locking, is managed by the drivers internally.
>
> We now have active-state in a centralized position, and need locking.
> Strictly speaking the locking is only needed for new drivers that use
> the new state, as the current drivers continue behaving as they used to.
>
> Add a mutex to the struct v4l2_subdev_state, along with a few helper
> functions for locking/unlocking.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> ---
> drivers/media/platform/rcar-vin/rcar-v4l2.c | 7 ++-
> drivers/media/platform/vsp1/vsp1_entity.c | 8 +++-
> drivers/media/v4l2-core/v4l2-subdev.c | 38 +++++++++++++---
> drivers/staging/media/tegra-video/vi.c | 8 +++-
> include/media/v4l2-subdev.h | 50 ++++++++++++++++++++-
> 5 files changed, 101 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> index 5aae01456c04..3759f4619a77 100644
> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> @@ -255,6 +255,7 @@ static int rvin_try_format(struct rvin_dev *vin, u32 which,
> {
> struct v4l2_subdev *sd = vin_to_source(vin);
> struct v4l2_subdev_state *sd_state;
> + static struct lock_class_key key;
> struct v4l2_subdev_format format = {
> .which = which,
> .pad = vin->parallel.source_pad,
> @@ -263,7 +264,11 @@ static int rvin_try_format(struct rvin_dev *vin, u32 which,
> u32 width, height;
> int ret;
>
> - sd_state = __v4l2_subdev_state_alloc(sd);
> + /*
> + * FIXME: Drop this call, drivers are not supposed to use
> + * __v4l2_subdev_state_alloc().
> + */
> + sd_state = __v4l2_subdev_state_alloc(sd, "rvin:state->lock", &key);
> if (IS_ERR(sd_state))
> return PTR_ERR(sd_state);
>
> diff --git a/drivers/media/platform/vsp1/vsp1_entity.c b/drivers/media/platform/vsp1/vsp1_entity.c
> index 869cadc1468d..a116a3362f9e 100644
> --- a/drivers/media/platform/vsp1/vsp1_entity.c
> +++ b/drivers/media/platform/vsp1/vsp1_entity.c
> @@ -613,6 +613,7 @@ int vsp1_entity_init(struct vsp1_device *vsp1, struct vsp1_entity *entity,
> const char *name, unsigned int num_pads,
> const struct v4l2_subdev_ops *ops, u32 function)
> {
> + static struct lock_class_key key;
> struct v4l2_subdev *subdev;
> unsigned int i;
> int ret;
> @@ -675,7 +676,12 @@ int vsp1_entity_init(struct vsp1_device *vsp1, struct vsp1_entity *entity,
> * Allocate the pad configuration to store formats and selection
> * rectangles.
> */
> - entity->config = __v4l2_subdev_state_alloc(&entity->subdev);
> + /*
> + * FIXME: Drop this call, drivers are not supposed to use
> + * __v4l2_subdev_state_alloc().
> + */
Feel free to remind me to fix this once the series lands :-)
> + entity->config = __v4l2_subdev_state_alloc(&entity->subdev,
> + "vsp1:config->lock", &key);
> if (IS_ERR(entity->config)) {
> media_entity_cleanup(&entity->subdev.entity);
> return PTR_ERR(entity->config);
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 779d7ae2262d..5322329d396f 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -27,8 +27,9 @@
> static int subdev_fh_init(struct v4l2_subdev_fh *fh, struct v4l2_subdev *sd)
> {
> struct v4l2_subdev_state *state;
> + static struct lock_class_key key;
>
> - state = __v4l2_subdev_state_alloc(sd);
> + state = __v4l2_subdev_state_alloc(sd, "fh->state->lock", &key);
> if (IS_ERR(state))
> return PTR_ERR(state);
>
> @@ -914,7 +915,9 @@ int v4l2_subdev_link_validate(struct media_link *link)
> }
> EXPORT_SYMBOL_GPL(v4l2_subdev_link_validate);
>
> -struct v4l2_subdev_state *__v4l2_subdev_state_alloc(struct v4l2_subdev *sd)
> +struct v4l2_subdev_state *
> +__v4l2_subdev_state_alloc(struct v4l2_subdev *sd, const char *lock_name,
> + struct lock_class_key *lock_key)
> {
> struct v4l2_subdev_state *state;
> int ret;
> @@ -923,6 +926,8 @@ struct v4l2_subdev_state *__v4l2_subdev_state_alloc(struct v4l2_subdev *sd)
> if (!state)
> return ERR_PTR(-ENOMEM);
>
> + __mutex_init(&state->lock, lock_name, lock_key);
> +
> if (sd->entity.num_pads) {
> state->pads = kvmalloc_array(sd->entity.num_pads,
> sizeof(*state->pads),
> @@ -954,6 +959,8 @@ void __v4l2_subdev_state_free(struct v4l2_subdev_state *state)
> if (!state)
> return;
>
> + mutex_destroy(&state->lock);
> +
> kvfree(state->pads);
> kfree(state);
> }
> @@ -988,11 +995,12 @@ void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
> }
> EXPORT_SYMBOL_GPL(v4l2_subdev_notify_event);
>
> -int v4l2_subdev_init_finalize(struct v4l2_subdev *sd)
> +int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
> + struct lock_class_key *key)
> {
> struct v4l2_subdev_state *state;
>
> - state = __v4l2_subdev_state_alloc(sd);
> + state = __v4l2_subdev_state_alloc(sd, name, key);
> if (IS_ERR(state))
> return PTR_ERR(state);
>
> @@ -1000,7 +1008,7 @@ int v4l2_subdev_init_finalize(struct v4l2_subdev *sd)
>
> return 0;
> }
> -EXPORT_SYMBOL_GPL(v4l2_subdev_init_finalize);
> +EXPORT_SYMBOL_GPL(__v4l2_subdev_init_finalize);
>
> void v4l2_subdev_cleanup(struct v4l2_subdev *sd)
> {
> @@ -1008,3 +1016,23 @@ void v4l2_subdev_cleanup(struct v4l2_subdev *sd)
> sd->active_state = NULL;
> }
> EXPORT_SYMBOL_GPL(v4l2_subdev_cleanup);
> +
> +struct v4l2_subdev_state *v4l2_subdev_lock_active_state(struct v4l2_subdev *sd)
> +{
> + mutex_lock(&sd->active_state->lock);
> +
> + return sd->active_state;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_lock_active_state);
> +
> +void v4l2_subdev_lock_state(struct v4l2_subdev_state *state)
> +{
> + mutex_lock(&state->lock);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_lock_state);
> +
> +void v4l2_subdev_unlock_state(struct v4l2_subdev_state *state)
> +{
> + mutex_unlock(&state->lock);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_unlock_state);
> diff --git a/drivers/staging/media/tegra-video/vi.c b/drivers/staging/media/tegra-video/vi.c
> index b01f19e0f332..b366b56df15c 100644
> --- a/drivers/staging/media/tegra-video/vi.c
> +++ b/drivers/staging/media/tegra-video/vi.c
> @@ -491,6 +491,7 @@ static int __tegra_channel_try_format(struct tegra_vi_channel *chan,
> struct v4l2_pix_format *pix)
> {
> const struct tegra_video_format *fmtinfo;
> + static struct lock_class_key key;
> struct v4l2_subdev *subdev;
> struct v4l2_subdev_format fmt;
> struct v4l2_subdev_state *sd_state;
> @@ -507,7 +508,12 @@ static int __tegra_channel_try_format(struct tegra_vi_channel *chan,
> if (!subdev)
> return -ENODEV;
>
> - sd_state = __v4l2_subdev_state_alloc(subdev);
> + /*
> + * FIXME: Drop this call, drivers are not supposed to use
> + * __v4l2_subdev_state_alloc().
> + */
> + sd_state = __v4l2_subdev_state_alloc(subdev, "tegra:state->lock",
> + &key);
> if (IS_ERR(sd_state))
> return PTR_ERR(sd_state);
> /*
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index eddf72768e10..867e19ef80bd 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -658,6 +658,7 @@ struct v4l2_subdev_pad_config {
> /**
> * struct v4l2_subdev_state - Used for storing subdev state information.
> *
> + * @lock: mutex for the state
> * @pads: &struct v4l2_subdev_pad_config array
> *
> * This structure only needs to be passed to the pad op if the 'which' field
> @@ -665,6 +666,8 @@ struct v4l2_subdev_pad_config {
> * %V4L2_SUBDEV_FORMAT_ACTIVE it is safe to pass %NULL.
> */
> struct v4l2_subdev_state {
> + /* lock for the struct v4l2_subdev_state fields */
> + struct mutex lock;
> struct v4l2_subdev_pad_config *pads;
> };
>
> @@ -1157,10 +1160,14 @@ int v4l2_subdev_link_validate(struct media_link *link);
> * __v4l2_subdev_state_alloc - allocate v4l2_subdev_state
> *
> * @sd: pointer to &struct v4l2_subdev for which the state is being allocated.
> + * @lock_name: name of the state lock
> + * @key: lock_class_key for the lock
> *
> * Must call __v4l2_subdev_state_free() when state is no longer needed.
> */
> -struct v4l2_subdev_state *__v4l2_subdev_state_alloc(struct v4l2_subdev *sd);
> +struct v4l2_subdev_state *__v4l2_subdev_state_alloc(struct v4l2_subdev *sd,
> + const char *lock_name,
> + struct lock_class_key *key);
>
> /**
> * __v4l2_subdev_state_free - free a v4l2_subdev_state
> @@ -1250,7 +1257,16 @@ void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
> *
> * The user must call v4l2_subdev_cleanup() when the subdev is being removed.
> */
> -int v4l2_subdev_init_finalize(struct v4l2_subdev *sd);
> +#define v4l2_subdev_init_finalize(sd) \
> + ({ \
> + static struct lock_class_key __key; \
> + const char *name = KBUILD_BASENAME \
> + ":" __stringify(__LINE__) ":sd->active_state->lock"; \
> + __v4l2_subdev_init_finalize(sd, name, &__key); \
> + })
> +
> +int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
> + struct lock_class_key *key);
>
> /**
> * v4l2_subdev_cleanup() - Releases the resources needed by the subdevice
> @@ -1275,4 +1291,34 @@ v4l2_subdev_get_active_state(struct v4l2_subdev *sd)
> return sd->active_state;
> }
>
> +/**
> + * v4l2_subdev_lock_active_state() - Locks and returns the active subdev state
> + * for the subdevice
> + * @sd: The subdevice
> + *
> + * Returns the locked active state for the subdevice, or NULL if the subdev
> + * does not support active state.
> + *
> + * The state must be unlocked with v4l2_subdev_unlock_state() after use.
> + */
> +struct v4l2_subdev_state *v4l2_subdev_lock_active_state(struct v4l2_subdev *sd);
> +
> +/**
> + * v4l2_subdev_lock_state() - Locks the subdev state
> + * @state: The subdevice state
> + *
> + * Locks the given subdev state.
> + *
> + * The state must be unlocked with v4l2_subdev_unlock_state() after use.
> + */
> +void v4l2_subdev_lock_state(struct v4l2_subdev_state *state);
> +
> +/**
> + * v4l2_subdev_unlock_state() - Unlocks the subdev state
> + * @state: The subdevice state
> + *
> + * Unlocks the given subdev state.
> + */
> +void v4l2_subdev_unlock_state(struct v4l2_subdev_state *state);
> +
> #endif
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2021-12-21 8:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-17 13:50 [PATCH v2 0/6] v4l: subdev active state Tomi Valkeinen
2021-12-17 13:50 ` [PATCH v2 1/6] media: subdev: rename subdev-state alloc & free Tomi Valkeinen
2021-12-17 13:50 ` [PATCH v2 2/6] media: subdev: add active state to struct v4l2_subdev Tomi Valkeinen
2021-12-21 8:05 ` Laurent Pinchart
2021-12-17 13:50 ` [PATCH v2 3/6] media: subdev: pass also the active state to subdevs from ioctls Tomi Valkeinen
2021-12-17 13:50 ` [PATCH v2 4/6] media: subdev: add subdev state locking Tomi Valkeinen
2021-12-21 8:11 ` Laurent Pinchart [this message]
2021-12-17 13:50 ` [PATCH v2 5/6] media: subdev: Add v4l2_subdev_lock_and_return_state() Tomi Valkeinen
2021-12-20 12:51 ` Sakari Ailus
2021-12-20 17:25 ` Sakari Ailus
2021-12-17 13:50 ` [PATCH v2 6/6] media: Documentation: add documentation about subdev state Tomi Valkeinen
2021-12-17 14:35 ` Hans Verkuil
2021-12-20 17:56 ` Sakari Ailus
2021-12-21 8:36 ` Laurent Pinchart
2021-12-21 10:27 ` Sakari Ailus
2021-12-21 10:33 ` Laurent Pinchart
2021-12-21 11:10 ` Sakari Ailus
2021-12-22 0:00 ` Laurent Pinchart
2022-02-07 9:19 ` Tomi Valkeinen
2022-02-07 20:31 ` Laurent Pinchart
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