On 04/08/18 14:44, Hans Verkuil wrote:
> From: Hans Verkuil <[email protected]>
>
> Add initial media request support:
>
> 1) Add MEDIA_IOC_REQUEST_ALLOC ioctl support to media-device.c
> 2) Add struct media_request to store request objects.
> 3) Add struct media_request_object to represent a request object.
> 4) Add MEDIA_REQUEST_IOC_QUEUE/REINIT ioctl support.
>
> Basic lifecycle: the application allocates a request, adds
> objects to it, queues the request, polls until it is completed
> and can then read the final values of the objects at the time
> of completion. When it closes the file descriptor the request
> memory will be freed (actually, when the last user of that request
> releases the request).
>
> Drivers will bind an object to a request (the 'adds objects to it'
> phase), when MEDIA_REQUEST_IOC_QUEUE is called the request is
> validated (req_validate op), then queued (the req_queue op).
>
> When done with an object it can either be unbound from the request
> (e.g. when the driver has finished with a vb2 buffer) or marked as
> completed (e.g. for controls associated with a buffer). When all
> objects in the request are completed (or unbound), then the request
> fd will signal an exception (poll).
>
> Signed-off-by: Hans Verkuil <[email protected]>
> Co-developed-by: Sakari Ailus <[email protected]>
> Signed-off-by: Sakari Ailus <[email protected]>
> Co-developed-by: Laurent Pinchart <[email protected]>
> Co-developed-by: Alexandre Courbot <[email protected]>
> ---
> drivers/media/Makefile | 3 +-
> drivers/media/media-device.c | 14 ++
> drivers/media/media-request.c | 423 ++++++++++++++++++++++++++++++++++
> include/media/media-device.h | 21 ++
> include/media/media-request.h | 327 ++++++++++++++++++++++++++
> 5 files changed, 787 insertions(+), 1 deletion(-)
> create mode 100644 drivers/media/media-request.c
> create mode 100644 include/media/media-request.h
>
<snip>
> +static long media_request_ioctl_queue(struct media_request *req)
> +{
> + struct media_device *mdev = req->mdev;
> + enum media_request_state state;
> + unsigned long flags;
> + int ret;
> +
> + dev_dbg(mdev->dev, "request: queue %s\n", req->debug_str);
> +
> + /*
> + * Ensure the request that is validated will be the one that gets queued
> + * next by serialising the queueing process. This mutex is also used
> + * to serialize with canceling a vb2 queue and with setting values such
> + * as controls in a request.
> + */
> + mutex_lock(&mdev->req_queue_mutex);
> +
> + media_request_get(req);
Here we get a reference to the request...
> +
> + spin_lock_irqsave(&req->lock, flags);
> + if (req->state == MEDIA_REQUEST_STATE_IDLE)
> + req->state = MEDIA_REQUEST_STATE_VALIDATING;
> + state = req->state;
> + spin_unlock_irqrestore(&req->lock, flags);
> + if (state != MEDIA_REQUEST_STATE_VALIDATING) {
> + dev_dbg(mdev->dev,
> + "request: unable to queue %s, request in state %s\n",
> + req->debug_str, media_request_state_str(state));
...but we didn't put it again in this error path. Thus this request is never
released.
Fixed by adding a media_request_put(req) here.
Found with v4l2-compliance.
> + mutex_unlock(&mdev->req_queue_mutex);
> + return -EBUSY;
> + }
> +
> + ret = mdev->ops->req_validate(req);
> +
> + /*
> + * If the req_validate was successful, then we mark the state as QUEUED
> + * and call req_queue. The reason we set the state first is that this
> + * allows req_queue to unbind or complete the queued objects in case
> + * they are immediately 'consumed'. State changes from QUEUED to another
> + * state can only happen if either the driver changes the state or if
> + * the user cancels the vb2 queue. The driver can only change the state
> + * after each object is queued through the req_queue op (and note that
> + * that op cannot fail), so setting the state to QUEUED up front is
> + * safe.
> + *
> + * The other reason for changing the state is if the vb2 queue is
> + * canceled, and that uses the req_queue_mutex which is still locked
> + * while req_queue is called, so that's safe as well.
> + */
> + spin_lock_irqsave(&req->lock, flags);
> + req->state = ret ? MEDIA_REQUEST_STATE_IDLE
> + : MEDIA_REQUEST_STATE_QUEUED;
> + spin_unlock_irqrestore(&req->lock, flags);
> +
> + if (!ret)
> + mdev->ops->req_queue(req);
> +
> + mutex_unlock(&mdev->req_queue_mutex);
> +
> + if (ret) {
> + dev_dbg(mdev->dev, "request: can't queue %s (%d)\n",
> + req->debug_str, ret);
> + media_request_put(req);
> + }
> +
> + return ret;
> +}
Regards,
Hans
