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Subject[PATCH v4 3/6] media: uvcvideo: Protect queue internals with helper
Date
The URB completion operation obtains the current buffer by reading
directly into the queue internal interface.

Protect this queue abstraction by providing a helper
uvc_queue_get_current_buffer() which can be used by both the decode
task, and the uvc_queue_next_buffer() functions.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

---

v2:
- Fix coding style of conditional statements

v3:
- No change

v4:
- Rebase on top of linux-media/master (v4.16-rc4, metadata additions)

drivers/media/usb/uvc/uvc_queue.c | 33 +++++++++++++++++++++++++++-----
drivers/media/usb/uvc/uvc_video.c | 6 +-----
drivers/media/usb/uvc/uvcvideo.h | 1 +-
3 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index fecccb5e7628..adcc4928fae4 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -429,6 +429,33 @@ void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect)
spin_unlock_irqrestore(&queue->irqlock, flags);
}

+/*
+ * uvc_queue_get_current_buffer: Obtain the current working output buffer
+ *
+ * Buffers may span multiple packets, and even URBs, therefore the active buffer
+ * remains on the queue until the EOF marker.
+ */
+static struct uvc_buffer *
+__uvc_queue_get_current_buffer(struct uvc_video_queue *queue)
+{
+ if (list_empty(&queue->irqqueue))
+ return NULL;
+
+ return list_first_entry(&queue->irqqueue, struct uvc_buffer, queue);
+}
+
+struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue)
+{
+ struct uvc_buffer *nextbuf;
+ unsigned long flags;
+
+ spin_lock_irqsave(&queue->irqlock, flags);
+ nextbuf = __uvc_queue_get_current_buffer(queue);
+ spin_unlock_irqrestore(&queue->irqlock, flags);
+
+ return nextbuf;
+}
+
struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
struct uvc_buffer *buf)
{
@@ -445,11 +472,7 @@ struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,

spin_lock_irqsave(&queue->irqlock, flags);
list_del(&buf->queue);
- if (!list_empty(&queue->irqqueue))
- nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
- queue);
- else
- nextbuf = NULL;
+ nextbuf = __uvc_queue_get_current_buffer(queue);
spin_unlock_irqrestore(&queue->irqlock, flags);

buf->state = buf->error ? UVC_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 0f6d488ab66b..7dd0dcb457f3 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1434,11 +1434,7 @@ static void uvc_video_complete(struct urb *urb)
return;
}

- spin_lock_irqsave(&queue->irqlock, flags);
- if (!list_empty(&queue->irqqueue))
- buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
- queue);
- spin_unlock_irqrestore(&queue->irqlock, flags);
+ buf = uvc_queue_get_current_buffer(queue);

if (vb2_qmeta) {
spin_lock_irqsave(&qmeta->irqlock, flags);
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index fcf3b0fa1ca9..ba792d91dad7 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -704,6 +704,7 @@ int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
struct uvc_buffer *buf);
+struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
int uvc_queue_mmap(struct uvc_video_queue *queue,
struct vm_area_struct *vma);
__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
--
git-series 0.9.1
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