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Subject[RFCv3 08/17] v4l2-ctrls: add core request API
Date
From: Hans Verkuil <hans.verkuil@cisco.com>

Add the four core request functions:

v4l2_ctrl_request_init() initializes a new (empty) request.
v4l2_ctrl_request_clone() resets a request based on another request
(or clears it if that request is NULL).
v4l2_ctrl_request_get(): increase refcount
v4l2_ctrl_request_put(): decrease refcount and delete if it reaches 0.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[acourbot@chromium.org: turn v4l2_ctrl_request_alloc into init function]
Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
---
drivers/media/v4l2-core/v4l2-ctrls.c | 106 ++++++++++++++++++++++++++++++++++-
include/media/v4l2-ctrls.h | 7 +++
2 files changed, 110 insertions(+), 3 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index 1ff8fc59fff5..c692a6d925c6 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -1878,6 +1878,7 @@ EXPORT_SYMBOL(v4l2_ctrl_find);
/* Allocate a new v4l2_ctrl_ref and hook it into the handler. */
static int handler_new_ref(struct v4l2_ctrl_handler *hdl,
struct v4l2_ctrl *ctrl,
+ struct v4l2_ctrl_ref **ctrl_ref,
bool from_other_dev)
{
struct v4l2_ctrl_ref *ref;
@@ -1885,6 +1886,10 @@ static int handler_new_ref(struct v4l2_ctrl_handler *hdl,
u32 id = ctrl->id;
u32 class_ctrl = V4L2_CTRL_ID2WHICH(id) | 1;
int bucket = id % hdl->nr_of_buckets; /* which bucket to use */
+ unsigned int sz_extra = 0;
+
+ if (ctrl_ref)
+ *ctrl_ref = NULL;

/*
* Automatically add the control class if it is not yet present and
@@ -1898,11 +1903,16 @@ static int handler_new_ref(struct v4l2_ctrl_handler *hdl,
if (hdl->error)
return hdl->error;

- new_ref = kzalloc(sizeof(*new_ref), GFP_KERNEL);
+ if (hdl->is_request)
+ sz_extra = ctrl->elems * ctrl->elem_size;
+ new_ref = kzalloc(sizeof(*new_ref) + sz_extra, GFP_KERNEL);
if (!new_ref)
return handler_set_err(hdl, -ENOMEM);
new_ref->ctrl = ctrl;
new_ref->from_other_dev = from_other_dev;
+ if (sz_extra)
+ new_ref->p_req.p = &new_ref[1];
+
if (ctrl->handler == hdl) {
/* By default each control starts in a cluster of its own.
new_ref->ctrl is basically a cluster array with one
@@ -1942,6 +1952,8 @@ static int handler_new_ref(struct v4l2_ctrl_handler *hdl,
/* Insert the control node in the hash */
new_ref->next = hdl->buckets[bucket];
hdl->buckets[bucket] = new_ref;
+ if (ctrl_ref)
+ *ctrl_ref = new_ref;

unlock:
mutex_unlock(hdl->lock);
@@ -2083,7 +2095,7 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
ctrl->type_ops->init(ctrl, idx, ctrl->p_new);
}

- if (handler_new_ref(hdl, ctrl, false)) {
+ if (handler_new_ref(hdl, ctrl, NULL, false)) {
kvfree(ctrl);
return NULL;
}
@@ -2276,7 +2288,7 @@ int v4l2_ctrl_add_handler(struct v4l2_ctrl_handler *hdl,
/* Filter any unwanted controls */
if (filter && !filter(ctrl))
continue;
- ret = handler_new_ref(hdl, ctrl, from_other_dev);
+ ret = handler_new_ref(hdl, ctrl, NULL, from_other_dev);
if (ret)
break;
}
@@ -2685,6 +2697,94 @@ int v4l2_querymenu(struct v4l2_ctrl_handler *hdl, struct v4l2_querymenu *qm)
}
EXPORT_SYMBOL(v4l2_querymenu);

+int v4l2_ctrl_request_init(struct v4l2_ctrl_handler *hdl)
+{
+ int err;
+
+ err = v4l2_ctrl_handler_init(hdl, 0);
+ if (err)
+ return err;
+ hdl->is_request = true;
+ kref_init(&hdl->ref);
+
+ return 0;
+}
+EXPORT_SYMBOL(v4l2_ctrl_request_init);
+
+int v4l2_ctrl_request_clone(struct v4l2_ctrl_handler *hdl,
+ const struct v4l2_ctrl_handler *from,
+ bool (*filter)(const struct v4l2_ctrl *ctrl))
+{
+ struct v4l2_ctrl_ref *ref;
+ int err;
+
+ if (WARN_ON(!hdl || hdl == from))
+ return -EINVAL;
+
+ if (hdl->error)
+ return hdl->error;
+
+ WARN_ON(hdl->lock != &hdl->_lock);
+ v4l2_ctrl_handler_free(hdl);
+ err = v4l2_ctrl_handler_init(hdl, (from->nr_of_buckets - 1) * 8);
+ hdl->is_request = true;
+ if (err)
+ return err;
+ if (!from)
+ return 0;
+
+ mutex_lock(from->lock);
+ list_for_each_entry(ref, &from->ctrl_refs, node) {
+ struct v4l2_ctrl *ctrl = ref->ctrl;
+ struct v4l2_ctrl_ref *new_ref;
+
+ /* Skip refs inherited from other devices */
+ if (ref->from_other_dev)
+ continue;
+ /* And buttons and control classes */
+ if (ctrl->type == V4L2_CTRL_TYPE_BUTTON ||
+ ctrl->type == V4L2_CTRL_TYPE_CTRL_CLASS)
+ continue;
+ /* Filter any unwanted controls */
+ if (filter && !filter(ctrl))
+ continue;
+ err = handler_new_ref(hdl, ctrl, &new_ref, false);
+ if (err)
+ break;
+ if (from->is_request)
+ ptr_to_ptr(ctrl, ref->p_req, new_ref->p_req);
+ else
+ ptr_to_ptr(ctrl, ctrl->p_cur, new_ref->p_req);
+ }
+ mutex_unlock(from->lock);
+ return err;
+}
+EXPORT_SYMBOL(v4l2_ctrl_request_clone);
+
+void v4l2_ctrl_request_get(struct v4l2_ctrl_handler *hdl)
+{
+ if (WARN_ON(!hdl->is_request))
+ return;
+ kref_get(&hdl->ref);
+}
+EXPORT_SYMBOL(v4l2_ctrl_request_get);
+
+static void v4l2_ctrl_request_release(struct kref *kref)
+{
+ struct v4l2_ctrl_handler *hdl =
+ container_of(kref, struct v4l2_ctrl_handler, ref);
+
+ v4l2_ctrl_handler_free(hdl);
+ kfree(hdl);
+}
+
+void v4l2_ctrl_request_put(struct v4l2_ctrl_handler *hdl)
+{
+ if (WARN_ON(!hdl->is_request))
+ return;
+ kref_put(&hdl->ref, v4l2_ctrl_request_release);
+}
+EXPORT_SYMBOL(v4l2_ctrl_request_put);

/* Some general notes on the atomic requirements of VIDIOC_G/TRY/S_EXT_CTRLS:

diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 22b6be78057f..bddceb794961 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -1052,6 +1052,13 @@ int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
*/
unsigned int v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait);

+int v4l2_ctrl_request_init(struct v4l2_ctrl_handler *hdl);
+int v4l2_ctrl_request_clone(struct v4l2_ctrl_handler *hdl,
+ const struct v4l2_ctrl_handler *from,
+ bool (*filter)(const struct v4l2_ctrl *ctrl));
+void v4l2_ctrl_request_get(struct v4l2_ctrl_handler *hdl);
+void v4l2_ctrl_request_put(struct v4l2_ctrl_handler *hdl);
+
/* Helpers for ioctl_ops */

/**
--
2.16.0.rc1.238.g530d649a79-goog
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