[RFCv3 PATCH 01/10] vb2: add debugging code to check for unbalanced ops.

[Hans Verkuil <hverkuil@xs4all.nl>]

From: Hans Verkuil <hans.verkuil@cisco.com>

When a vb2_queue is freed check if all the mem_ops and queue ops were balanced.
So the number of calls to e.g. buf_finish has to match the number of calls to
buf_prepare, etc.

This code is only enabled if CONFIG_VIDEO_ADV_DEBUG is set.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 233 ++++++++++++++++++++++++-------
 include/media/videobuf2-core.h           |  43 ++++++
 2 files changed, 226 insertions(+), 50 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 5a5fb7f..07b58bd 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -33,12 +33,63 @@ module_param(debug, int, 0644);
 			printk(KERN_DEBUG "vb2: " fmt, ## arg);		\
 	} while (0)
 
-#define call_memop(q, op, args...)					\
-	(((q)->mem_ops->op) ?						\
-		((q)->mem_ops->op(args)) : 0)
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+
+/*
+ * If advanced debugging is on, then count how often each op is called,
+ * which can either be per-buffer or per-queue.
+ *
+ * If the op failed then the 'fail_' variant is called to decrease the
+ * counter. That makes it easy to check that the 'init' and 'cleanup'
+ * (and variations thereof) stay balanced.
+ */
+
+#define call_memop(vb, op, args...)					\
+({									\
+	struct vb2_queue *_q = (vb)->vb2_queue;				\
+	dprintk(2, "call_memop(%p, %d, %s)%s\n",			\
+		_q, (vb)->v4l2_buf.index, #op,				\
+		_q->mem_ops->op ? "" : " (nop)");			\
+	(vb)->cnt_mem_ ## op++;						\
+	_q->mem_ops->op ? _q->mem_ops->op(args) : 0;			\
+})
+#define fail_memop(vb, op) ((vb)->cnt_mem_ ## op--)
+
+#define call_qop(q, op, args...)					\
+({									\
+	dprintk(2, "call_qop(%p, %s)%s\n", q, #op,			\
+		(q)->ops->op ? "" : " (nop)");				\
+	(q)->cnt_ ## op++;						\
+	(q)->ops->op ? (q)->ops->op(args) : 0;				\
+})
+#define fail_qop(q, op) ((q)->cnt_ ## op--)
+
+#define call_vb_qop(vb, op, args...)					\
+({									\
+	struct vb2_queue *_q = (vb)->vb2_queue;				\
+	dprintk(2, "call_vb_qop(%p, %d, %s)%s\n",			\
+		_q, (vb)->v4l2_buf.index, #op,				\
+		_q->ops->op ? "" : " (nop)");				\
+	(vb)->cnt_ ## op++;						\
+	_q->ops->op ? _q->ops->op(args) : 0;				\
+})
+#define fail_vb_qop(vb, op) ((vb)->cnt_ ## op--)
+
+#else
+
+#define call_memop(vb, op, args...)					\
+	((vb)->vb2_queue->mem_ops->op ? (vb)->vb2_queue->mem_ops->op(args) : 0)
+#define fail_memop(vb, op)
 
 #define call_qop(q, op, args...)					\
-	(((q)->ops->op) ? ((q)->ops->op(args)) : 0)
+	((q)->ops->op ? (q)->ops->op(args) : 0)
+#define fail_qop(q, op)
+
+#define call_vb_qop(vb, op, args...)					\
+	((vb)->vb2_queue->ops->op ? (vb)->vb2_queue->ops->op(args) : 0)
+#define fail_vb_qop(vb, op)
+
+#endif
 
 #define V4L2_BUFFER_MASK_FLAGS	(V4L2_BUF_FLAG_MAPPED | V4L2_BUF_FLAG_QUEUED | \
 				 V4L2_BUF_FLAG_DONE | V4L2_BUF_FLAG_ERROR | \
@@ -61,7 +112,7 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
 	for (plane = 0; plane < vb->num_planes; ++plane) {
 		unsigned long size = PAGE_ALIGN(q->plane_sizes[plane]);
 
-		mem_priv = call_memop(q, alloc, q->alloc_ctx[plane],
+		mem_priv = call_memop(vb, alloc, q->alloc_ctx[plane],
 				      size, q->gfp_flags);
 		if (IS_ERR_OR_NULL(mem_priv))
 			goto free;
@@ -73,9 +124,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
 
 	return 0;
 free:
+	fail_memop(vb, alloc);
 	/* Free already allocated memory if one of the allocations failed */
 	for (; plane > 0; --plane) {
-		call_memop(q, put, vb->planes[plane - 1].mem_priv);
+		call_memop(vb, put, vb->planes[plane - 1].mem_priv);
 		vb->planes[plane - 1].mem_priv = NULL;
 	}
 
@@ -87,11 +139,10 @@ free:
  */
 static void __vb2_buf_mem_free(struct vb2_buffer *vb)
 {
-	struct vb2_queue *q = vb->vb2_queue;
 	unsigned int plane;
 
 	for (plane = 0; plane < vb->num_planes; ++plane) {
-		call_memop(q, put, vb->planes[plane].mem_priv);
+		call_memop(vb, put, vb->planes[plane].mem_priv);
 		vb->planes[plane].mem_priv = NULL;
 		dprintk(3, "Freed plane %d of buffer %d\n", plane,
 			vb->v4l2_buf.index);
@@ -104,12 +155,11 @@ static void __vb2_buf_mem_free(struct vb2_buffer *vb)
  */
 static void __vb2_buf_userptr_put(struct vb2_buffer *vb)
 {
-	struct vb2_queue *q = vb->vb2_queue;
 	unsigned int plane;
 
 	for (plane = 0; plane < vb->num_planes; ++plane) {
 		if (vb->planes[plane].mem_priv)
-			call_memop(q, put_userptr, vb->planes[plane].mem_priv);
+			call_memop(vb, put_userptr, vb->planes[plane].mem_priv);
 		vb->planes[plane].mem_priv = NULL;
 	}
 }
@@ -118,15 +168,15 @@ static void __vb2_buf_userptr_put(struct vb2_buffer *vb)
  * __vb2_plane_dmabuf_put() - release memory associated with
  * a DMABUF shared plane
  */
-static void __vb2_plane_dmabuf_put(struct vb2_queue *q, struct vb2_plane *p)
+static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb, struct vb2_plane *p)
 {
 	if (!p->mem_priv)
 		return;
 
 	if (p->dbuf_mapped)
-		call_memop(q, unmap_dmabuf, p->mem_priv);
+		call_memop(vb, unmap_dmabuf, p->mem_priv);
 
-	call_memop(q, detach_dmabuf, p->mem_priv);
+	call_memop(vb, detach_dmabuf, p->mem_priv);
 	dma_buf_put(p->dbuf);
 	memset(p, 0, sizeof(*p));
 }
@@ -137,11 +187,10 @@ static void __vb2_plane_dmabuf_put(struct vb2_queue *q, struct vb2_plane *p)
  */
 static void __vb2_buf_dmabuf_put(struct vb2_buffer *vb)
 {
-	struct vb2_queue *q = vb->vb2_queue;
 	unsigned int plane;
 
 	for (plane = 0; plane < vb->num_planes; ++plane)
-		__vb2_plane_dmabuf_put(q, &vb->planes[plane]);
+		__vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
 }
 
 /**
@@ -246,10 +295,11 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum v4l2_memory memory,
 			 * callback, if given. An error in initialization
 			 * results in queue setup failure.
 			 */
-			ret = call_qop(q, buf_init, vb);
+			ret = call_vb_qop(vb, buf_init, vb);
 			if (ret) {
 				dprintk(1, "Buffer %d %p initialization"
 					" failed\n", buffer, vb);
+				fail_vb_qop(vb, buf_init);
 				__vb2_buf_mem_free(vb);
 				kfree(vb);
 				break;
@@ -321,18 +371,77 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 	}
 
 	/* Call driver-provided cleanup function for each buffer, if provided */
-	if (q->ops->buf_cleanup) {
-		for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
-		     ++buffer) {
-			if (NULL == q->bufs[buffer])
-				continue;
-			q->ops->buf_cleanup(q->bufs[buffer]);
-		}
+	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
+	     ++buffer) {
+		if (q->bufs[buffer])
+			call_vb_qop(q->bufs[buffer], buf_cleanup, q->bufs[buffer]);
 	}
 
 	/* Release video buffer memory */
 	__vb2_free_mem(q, buffers);
 
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+	/*
+	 * Check that all the calls were balances during the life-time of this
+	 * queue. If not (or if the debug level is 1 or up), then dump the
+	 * counters to the kernel log.
+	 */
+	if (q->num_buffers) {
+		bool unbalanced = q->cnt_start_streaming != q->cnt_stop_streaming ||
+				  q->cnt_wait_prepare != q->cnt_wait_finish;
+
+		if (unbalanced || debug) {
+			pr_info("vb2: counters for queue %p:%s\n", q,
+				unbalanced ? " UNBALANCED!" : "");
+			pr_info("vb2:     setup: %u start_streaming: %u stop_streaming: %u\n",
+				q->cnt_queue_setup, q->cnt_start_streaming,
+				q->cnt_stop_streaming);
+			pr_info("vb2:     wait_prepare: %u wait_finish: %u\n",
+				q->cnt_wait_prepare, q->cnt_wait_finish);
+		}
+		q->cnt_queue_setup = 0;
+		q->cnt_wait_prepare = 0;
+		q->cnt_wait_finish = 0;
+		q->cnt_start_streaming = 0;
+		q->cnt_stop_streaming = 0;
+	}
+	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+		struct vb2_buffer *vb = q->bufs[buffer];
+		bool unbalanced = vb->cnt_mem_alloc != vb->cnt_mem_put ||
+				  vb->cnt_mem_prepare != vb->cnt_mem_finish ||
+				  vb->cnt_mem_get_userptr != vb->cnt_mem_put_userptr ||
+				  vb->cnt_mem_attach_dmabuf != vb->cnt_mem_detach_dmabuf ||
+				  vb->cnt_mem_map_dmabuf != vb->cnt_mem_unmap_dmabuf ||
+				  vb->cnt_buf_queue != vb->cnt_buf_done ||
+				  vb->cnt_buf_prepare != vb->cnt_buf_finish ||
+				  vb->cnt_buf_init != vb->cnt_buf_cleanup;
+
+		if (unbalanced || debug) {
+			pr_info("vb2:   counters for queue %p, buffer %d:%s\n",
+				q, buffer, unbalanced ? " UNBALANCED!" : "");
+			pr_info("vb2:     buf_init: %u buf_cleanup: %u buf_prepare: %u buf_finish: %u\n",
+				vb->cnt_buf_init, vb->cnt_buf_cleanup,
+				vb->cnt_buf_prepare, vb->cnt_buf_finish);
+			pr_info("vb2:     buf_queue: %u buf_done: %u\n",
+				vb->cnt_buf_queue, vb->cnt_buf_done);
+			pr_info("vb2:     alloc: %u put: %u prepare: %u finish: %u mmap: %u\n",
+				vb->cnt_mem_alloc, vb->cnt_mem_put,
+				vb->cnt_mem_prepare, vb->cnt_mem_finish,
+				vb->cnt_mem_mmap);
+			pr_info("vb2:     get_userptr: %u put_userptr: %u\n",
+				vb->cnt_mem_get_userptr, vb->cnt_mem_put_userptr);
+			pr_info("vb2:     attach_dmabuf: %u detach_dmabuf: %u map_dmabuf: %u unmap_dmabuf: %u\n",
+				vb->cnt_mem_attach_dmabuf, vb->cnt_mem_detach_dmabuf,
+				vb->cnt_mem_map_dmabuf, vb->cnt_mem_unmap_dmabuf);
+			pr_info("vb2:     get_dmabuf: %u num_users: %u vaddr: %u cookie: %u\n",
+				vb->cnt_mem_get_dmabuf,
+				vb->cnt_mem_num_users,
+				vb->cnt_mem_vaddr,
+				vb->cnt_mem_cookie);
+		}
+	}
+#endif
+
 	/* Free videobuf buffers */
 	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
 	     ++buffer) {
@@ -424,7 +533,7 @@ static bool __buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb)
 		 * case anyway. If num_users() returns more than 1,
 		 * we are not the only user of the plane's memory.
 		 */
-		if (mem_priv && call_memop(q, num_users, mem_priv) > 1)
+		if (mem_priv && call_memop(vb, num_users, mem_priv) > 1)
 			return true;
 	}
 	return false;
@@ -703,8 +812,10 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	 */
 	ret = call_qop(q, queue_setup, q, NULL, &num_buffers, &num_planes,
 		       q->plane_sizes, q->alloc_ctx);
-	if (ret)
+	if (ret) {
+		fail_qop(q, queue_setup);
 		return ret;
+	}
 
 	/* Finally, allocate buffers and video memory */
 	ret = __vb2_queue_alloc(q, req->memory, num_buffers, num_planes);
@@ -723,6 +834,8 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 
 		ret = call_qop(q, queue_setup, q, NULL, &num_buffers,
 			       &num_planes, q->plane_sizes, q->alloc_ctx);
+		if (ret)
+			fail_qop(q, queue_setup);
 
 		if (!ret && allocated_buffers < num_buffers)
 			ret = -ENOMEM;
@@ -803,8 +916,10 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
 	 */
 	ret = call_qop(q, queue_setup, q, &create->format, &num_buffers,
 		       &num_planes, q->plane_sizes, q->alloc_ctx);
-	if (ret)
+	if (ret) {
+		fail_qop(q, queue_setup);
 		return ret;
+	}
 
 	/* Finally, allocate buffers and video memory */
 	ret = __vb2_queue_alloc(q, create->memory, num_buffers,
@@ -828,6 +943,8 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
 		 */
 		ret = call_qop(q, queue_setup, q, &create->format, &num_buffers,
 			       &num_planes, q->plane_sizes, q->alloc_ctx);
+		if (ret)
+			fail_qop(q, queue_setup);
 
 		if (!ret && allocated_buffers < num_buffers)
 			ret = -ENOMEM;
@@ -882,12 +999,10 @@ EXPORT_SYMBOL_GPL(vb2_create_bufs);
  */
 void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no)
 {
-	struct vb2_queue *q = vb->vb2_queue;
-
 	if (plane_no > vb->num_planes || !vb->planes[plane_no].mem_priv)
 		return NULL;
 
-	return call_memop(q, vaddr, vb->planes[plane_no].mem_priv);
+	return call_memop(vb, vaddr, vb->planes[plane_no].mem_priv);
 
 }
 EXPORT_SYMBOL_GPL(vb2_plane_vaddr);
@@ -905,12 +1020,10 @@ EXPORT_SYMBOL_GPL(vb2_plane_vaddr);
  */
 void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no)
 {
-	struct vb2_queue *q = vb->vb2_queue;
-
 	if (plane_no > vb->num_planes || !vb->planes[plane_no].mem_priv)
 		return NULL;
 
-	return call_memop(q, cookie, vb->planes[plane_no].mem_priv);
+	return call_memop(vb, cookie, vb->planes[plane_no].mem_priv);
 }
 EXPORT_SYMBOL_GPL(vb2_plane_cookie);
 
@@ -938,12 +1051,19 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 	if (state != VB2_BUF_STATE_DONE && state != VB2_BUF_STATE_ERROR)
 		return;
 
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+	/*
+	 * Although this is not a callback, it still does have to balance
+	 * with the buf_queue op. So update this counter manually.
+	 */
+	vb->cnt_buf_done++;
+#endif
 	dprintk(4, "Done processing on buffer %d, state: %d\n",
 			vb->v4l2_buf.index, state);
 
 	/* sync buffers */
 	for (plane = 0; plane < vb->num_planes; ++plane)
-		call_memop(q, finish, vb->planes[plane].mem_priv);
+		call_memop(vb, finish, vb->planes[plane].mem_priv);
 
 	/* Add the buffer to the done buffers list */
 	spin_lock_irqsave(&q->done_lock, flags);
@@ -1067,19 +1187,20 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 
 		/* Release previously acquired memory if present */
 		if (vb->planes[plane].mem_priv)
-			call_memop(q, put_userptr, vb->planes[plane].mem_priv);
+			call_memop(vb, put_userptr, vb->planes[plane].mem_priv);
 
 		vb->planes[plane].mem_priv = NULL;
 		vb->v4l2_planes[plane].m.userptr = 0;
 		vb->v4l2_planes[plane].length = 0;
 
 		/* Acquire each plane's memory */
-		mem_priv = call_memop(q, get_userptr, q->alloc_ctx[plane],
+		mem_priv = call_memop(vb, get_userptr, q->alloc_ctx[plane],
 				      planes[plane].m.userptr,
 				      planes[plane].length, write);
 		if (IS_ERR_OR_NULL(mem_priv)) {
 			dprintk(1, "qbuf: failed acquiring userspace "
 						"memory for plane %d\n", plane);
+			fail_memop(vb, get_userptr);
 			ret = mem_priv ? PTR_ERR(mem_priv) : -EINVAL;
 			goto err;
 		}
@@ -1090,9 +1211,10 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	 * Call driver-specific initialization on the newly acquired buffer,
 	 * if provided.
 	 */
-	ret = call_qop(q, buf_init, vb);
+	ret = call_vb_qop(vb, buf_init, vb);
 	if (ret) {
 		dprintk(1, "qbuf: buffer initialization failed\n");
+		fail_vb_qop(vb, buf_init);
 		goto err;
 	}
 
@@ -1108,7 +1230,7 @@ err:
 	/* In case of errors, release planes that were already acquired */
 	for (plane = 0; plane < vb->num_planes; ++plane) {
 		if (vb->planes[plane].mem_priv)
-			call_memop(q, put_userptr, vb->planes[plane].mem_priv);
+			call_memop(vb, put_userptr, vb->planes[plane].mem_priv);
 		vb->planes[plane].mem_priv = NULL;
 		vb->v4l2_planes[plane].m.userptr = 0;
 		vb->v4l2_planes[plane].length = 0;
@@ -1173,14 +1295,15 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 		dprintk(1, "qbuf: buffer for plane %d changed\n", plane);
 
 		/* Release previously acquired memory if present */
-		__vb2_plane_dmabuf_put(q, &vb->planes[plane]);
+		__vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
 		memset(&vb->v4l2_planes[plane], 0, sizeof(struct v4l2_plane));
 
 		/* Acquire each plane's memory */
-		mem_priv = call_memop(q, attach_dmabuf, q->alloc_ctx[plane],
+		mem_priv = call_memop(vb, attach_dmabuf, q->alloc_ctx[plane],
 			dbuf, planes[plane].length, write);
 		if (IS_ERR(mem_priv)) {
 			dprintk(1, "qbuf: failed to attach dmabuf\n");
+			fail_memop(vb, attach_dmabuf);
 			ret = PTR_ERR(mem_priv);
 			dma_buf_put(dbuf);
 			goto err;
@@ -1195,10 +1318,11 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	 * the buffer(s)..
 	 */
 	for (plane = 0; plane < vb->num_planes; ++plane) {
-		ret = call_memop(q, map_dmabuf, vb->planes[plane].mem_priv);
+		ret = call_memop(vb, map_dmabuf, vb->planes[plane].mem_priv);
 		if (ret) {
 			dprintk(1, "qbuf: failed to map dmabuf for plane %d\n",
 				plane);
+			fail_memop(vb, map_dmabuf);
 			goto err;
 		}
 		vb->planes[plane].dbuf_mapped = 1;
@@ -1208,9 +1332,10 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	 * Call driver-specific initialization on the newly acquired buffer,
 	 * if provided.
 	 */
-	ret = call_qop(q, buf_init, vb);
+	ret = call_vb_qop(vb, buf_init, vb);
 	if (ret) {
 		dprintk(1, "qbuf: buffer initialization failed\n");
+		fail_vb_qop(vb, buf_init);
 		goto err;
 	}
 
@@ -1242,9 +1367,9 @@ static void __enqueue_in_driver(struct vb2_buffer *vb)
 
 	/* sync buffers */
 	for (plane = 0; plane < vb->num_planes; ++plane)
-		call_memop(q, prepare, vb->planes[plane].mem_priv);
+		call_memop(vb, prepare, vb->planes[plane].mem_priv);
 
-	q->ops->buf_queue(vb);
+	call_vb_qop(vb, buf_queue, vb);
 }
 
 static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
@@ -1295,8 +1420,11 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 		ret = -EINVAL;
 	}
 
-	if (!ret)
-		ret = call_qop(q, buf_prepare, vb);
+	if (!ret) {
+		ret = call_vb_qop(vb, buf_prepare, vb);
+		if (ret)
+			fail_vb_qop(vb, buf_prepare);
+	}
 	if (ret)
 		dprintk(1, "qbuf: buffer preparation failed: %d\n", ret);
 	vb->state = ret ? VB2_BUF_STATE_DEQUEUED : VB2_BUF_STATE_PREPARED;
@@ -1393,6 +1521,8 @@ static int vb2_start_streaming(struct vb2_queue *q)
 
 	/* Tell the driver to start streaming */
 	ret = call_qop(q, start_streaming, q, atomic_read(&q->queued_count));
+	if (ret)
+		fail_qop(q, start_streaming);
 
 	/*
 	 * If there are not enough buffers queued to start streaming, then
@@ -1639,7 +1769,7 @@ static void __vb2_dqbuf(struct vb2_buffer *vb)
 		for (i = 0; i < vb->num_planes; ++i) {
 			if (!vb->planes[i].dbuf_mapped)
 				continue;
-			call_memop(q, unmap_dmabuf, vb->planes[i].mem_priv);
+			call_memop(vb, unmap_dmabuf, vb->planes[i].mem_priv);
 			vb->planes[i].dbuf_mapped = 0;
 		}
 }
@@ -1657,7 +1787,7 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
 	if (ret < 0)
 		return ret;
 
-	ret = call_qop(q, buf_finish, vb);
+	ret = call_vb_qop(vb, buf_finish, vb);
 	if (ret) {
 		dprintk(1, "dqbuf: buffer finish failed\n");
 		return ret;
@@ -1945,10 +2075,11 @@ int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb)
 
 	vb_plane = &vb->planes[eb->plane];
 
-	dbuf = call_memop(q, get_dmabuf, vb_plane->mem_priv, eb->flags & O_ACCMODE);
+	dbuf = call_memop(vb, get_dmabuf, vb_plane->mem_priv, eb->flags & O_ACCMODE);
 	if (IS_ERR_OR_NULL(dbuf)) {
 		dprintk(1, "Failed to export buffer %d, plane %d\n",
 			eb->index, eb->plane);
+		fail_memop(vb, get_dmabuf);
 		return -EINVAL;
 	}
 
@@ -2040,9 +2171,11 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
 		return -EINVAL;
 	}
 
-	ret = call_memop(q, mmap, vb->planes[plane].mem_priv, vma);
-	if (ret)
+	ret = call_memop(vb, mmap, vb->planes[plane].mem_priv, vma);
+	if (ret) {
+		fail_memop(vb, mmap);
 		return ret;
+	}
 
 	dprintk(3, "Buffer %d, plane %d successfully mapped\n", buffer, plane);
 	return 0;
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index bef53ce..f04eb28 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -203,6 +203,37 @@ struct vb2_buffer {
 	struct list_head	done_entry;
 
 	struct vb2_plane	planes[VIDEO_MAX_PLANES];
+
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+	/*
+	 * Counters for how often these buffer-related ops are
+	 * called. Used to check for unbalanced ops.
+	 */
+	u32		cnt_mem_alloc;
+	u32		cnt_mem_put;
+	u32		cnt_mem_get_dmabuf;
+	u32		cnt_mem_get_userptr;
+	u32		cnt_mem_put_userptr;
+	u32		cnt_mem_prepare;
+	u32		cnt_mem_finish;
+	u32		cnt_mem_attach_dmabuf;
+	u32		cnt_mem_detach_dmabuf;
+	u32		cnt_mem_map_dmabuf;
+	u32		cnt_mem_unmap_dmabuf;
+	u32		cnt_mem_vaddr;
+	u32		cnt_mem_cookie;
+	u32		cnt_mem_num_users;
+	u32		cnt_mem_mmap;
+
+	u32		cnt_buf_init;
+	u32		cnt_buf_prepare;
+	u32		cnt_buf_finish;
+	u32		cnt_buf_cleanup;
+	u32		cnt_buf_queue;
+
+	/* This counts the number of calls to vb2_buffer_done() */
+	u32		cnt_buf_done;
+#endif
 };
 
 /**
@@ -364,6 +395,18 @@ struct vb2_queue {
 	unsigned int			retry_start_streaming:1;
 
 	struct vb2_fileio_data		*fileio;
+
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+	/*
+	 * Counters for how often these queue-related ops are
+	 * called. Used to check for unbalanced ops.
+	 */
+	u32				cnt_queue_setup;
+	u32				cnt_wait_prepare;
+	u32				cnt_wait_finish;
+	u32				cnt_start_streaming;
+	u32				cnt_stop_streaming;
+#endif
 };
 
 void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
-- 
1.8.4.rc3