From: Hans Verkuil <hans.verk...@cisco.com>
Add helper functions to prevent a completed request from being
re-inited while it is being accessed.
Signed-off-by: Hans Verkuil <hans.verk...@cisco.com>
Reviewed-by: Tomasz Figa <tf...@chromium.org>
---
drivers/media/media-request.c | 10 +++++++
include/media/media-request.h | 56 +++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)
diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
index 4cee67e6657e..414197645e09 100644
--- a/drivers/media/media-request.c
+++ b/drivers/media/media-request.c
@@ -43,6 +43,7 @@ static void media_request_clean(struct media_request *req)
/* Just a sanity check. No other code path is allowed to change this. */
WARN_ON(req->state != MEDIA_REQUEST_STATE_CLEANING);
WARN_ON(req->updating_count);
+ WARN_ON(req->access_count);
list_for_each_entry_safe(obj, obj_safe, &req->objects, list) {
media_request_object_unbind(obj);
@@ -50,6 +51,7 @@ static void media_request_clean(struct media_request *req)
}
req->updating_count = 0;
+ req->access_count = 0;
WARN_ON(req->num_incomplete_objects);
req->num_incomplete_objects = 0;
wake_up_interruptible_all(&req->poll_wait);
@@ -198,6 +200,13 @@ static long media_request_ioctl_reinit(struct
media_request *req)
spin_unlock_irqrestore(&req->lock, flags);
return -EBUSY;
}
+ if (req->access_count) {
+ dev_dbg(mdev->dev,
+ "request: %s is being accessed, cannot reinit\n",
+ req->debug_str);
+ spin_unlock_irqrestore(&req->lock, flags);
+ return -EBUSY;
+ }
req->state = MEDIA_REQUEST_STATE_CLEANING;
spin_unlock_irqrestore(&req->lock, flags);
@@ -313,6 +322,7 @@ int media_request_alloc(struct media_device *mdev, int
*alloc_fd)
spin_lock_init(&req->lock);
init_waitqueue_head(&req->poll_wait);
req->updating_count = 0;
+ req->access_count = 0;
*alloc_fd = fd;
diff --git a/include/media/media-request.h b/include/media/media-request.h
index ac02019c1d77..d8c8db89dbde 100644
--- a/include/media/media-request.h
+++ b/include/media/media-request.h
@@ -53,6 +53,7 @@ struct media_request_object;
* @debug_str: Prefix for debug messages (process name:fd)
* @state: The state of the request
* @updating_count: count the number of request updates that are in progress
+ * @access_count: count the number of request accesses that are in progress
* @objects: List of @struct media_request_object request objects
* @num_incomplete_objects: The number of incomplete objects in the request
* @poll_wait: Wait queue for poll
@@ -64,6 +65,7 @@ struct media_request {
char debug_str[TASK_COMM_LEN + 11];
enum media_request_state state;
unsigned int updating_count;
+ unsigned int access_count;
struct list_head objects;
unsigned int num_incomplete_objects;
struct wait_queue_head poll_wait;
@@ -72,6 +74,50 @@ struct media_request {
#ifdef CONFIG_MEDIA_CONTROLLER
+/**
+ * media_request_lock_for_access - Lock the request to access its objects
+ *
+ * @req: The media request
+ *
+ * Use before accessing a completed request. A reference to the request must
+ * be held during the access. This usually takes place automatically through
+ * a file handle. Use @media_request_unlock_for_access when done.
+ */
+static inline int __must_check
+media_request_lock_for_access(struct media_request *req)
+{
+ unsigned long flags;
+ int ret = -EBUSY;
+
+ spin_lock_irqsave(&req->lock, flags);
+ if (req->state == MEDIA_REQUEST_STATE_COMPLETE) {
+ req->access_count++;
+ ret = 0;
+ }
+ spin_unlock_irqrestore(&req->lock, flags);
+
+ return ret;
+}
+
+/**
+ * media_request_unlock_for_access - Unlock a request previously locked for
+ * access
+ *
+ * @req: The media request
+ *
+ * Unlock a request that has previously been locked using
+ * @media_request_lock_for_access.
+ */
+static inline void media_request_unlock_for_access(struct media_request *req)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&req->lock, flags);
+ if (!WARN_ON(!req->access_count))
+ req->access_count--;
+ spin_unlock_irqrestore(&req->lock, flags);
+}
+
/**
* media_request_lock_for_update - Lock the request for updating its objects
*
@@ -333,6 +379,16 @@ void media_request_object_complete(struct
media_request_object *obj);
#else
+static inline int __must_check
+media_request_lock_for_access(struct media_request *req)
+{
+ return -EINVAL;
+}
+
+static inline void media_request_unlock_for_access(struct media_request *req)
+{
+}
+
static inline int __must_check
media_request_lock_for_update(struct media_request *req)
{
--
2.18.0
