From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Add media_request_get_by_fd() to find a request based on the file
descriptor.
The caller has to call media_request_put() for the returned
request since this function increments the refcount.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
drivers/media/media-request.c | 40 +++++++++++++++++++++++++++++++++++
include/media/media-request.h | 24 +++++++++++++++++++++
2 files changed, 64 insertions(+)
diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
index 253068f51a1f..4b523f3a03a3 100644
--- a/drivers/media/media-request.c
+++ b/drivers/media/media-request.c
@@ -231,6 +231,46 @@ static const struct file_operations request_fops = {
.release = media_request_close,
};
+struct media_request *
+media_request_get_by_fd(struct media_device *mdev, int request_fd)
+{
+ struct file *filp;
+ struct media_request *req;
+
+ if (!mdev || !mdev->ops ||
+ !mdev->ops->req_validate || !mdev->ops->req_queue)
+ return ERR_PTR(-EPERM);
+
+ filp = fget(request_fd);
+ if (!filp)
+ return ERR_PTR(-ENOENT);
+
+ if (filp->f_op != &request_fops)
+ goto err_fput;
+ req = filp->private_data;
+ if (req->mdev != mdev)
+ goto err_fput;
+
+ /*
+ * Note: as long as someone has an open filehandle of the request,
+ * the request can never be released. The fget() above ensures that
+ * even if userspace closes the request filehandle, the release()
+ * fop won't be called, so the media_request_get() always succeeds
+ * and there is no race condition where the request was released
+ * before media_request_get() is called.
+ */
+ media_request_get(req);
+ fput(filp);
+
+ return req;
+
+err_fput:
+ fput(filp);
+
+ return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL_GPL(media_request_get_by_fd);
+
int media_request_alloc(struct media_device *mdev,
struct media_request_alloc *alloc)
{
diff --git a/include/media/media-request.h b/include/media/media-request.h
index fe5a04fb970c..66ec9d09fcd8 100644
--- a/include/media/media-request.h
+++ b/include/media/media-request.h
@@ -143,6 +143,24 @@ static inline void media_request_get(struct media_request *req)
*/
void media_request_put(struct media_request *req);
+/**
+ * media_request_get_by_fd - Get a media request by fd
+ *
+ * @mdev: Media device this request belongs to
+ * @request_fd: The file descriptor of the request
+ *
+ * Get the request represented by @request_fd that is owned
+ * by the media device.
+ *
+ * Return a -EPERM error pointer if requests are not supported
+ * by this driver. Return -ENOENT if the request was not found.
+ * Return the pointer to the request if found: the caller will
+ * have to call @media_request_put when it finished using the
+ * request.
+ */
+struct media_request *
+media_request_get_by_fd(struct media_device *mdev, int request_fd);
+
/**
* media_request_alloc - Allocate the media request
*
@@ -164,6 +182,12 @@ static inline void media_request_put(struct media_request *req)
{
}
+static inline struct media_request *
+media_request_get_by_fd(struct media_device *mdev, int request_fd)
+{
+ return ERR_PTR(-EPERM);
+}
+
#endif
/**
--
2.18.0
