[REVIEWv4 PATCH 00/18] vb2: fixes, balancing callbacks (PART 1)

[REVIEWv4 PATCH 00/18] vb2: fixes, balancing callbacks (PART 1)

[Hans Verkuil]

The fourth version, hopefully the last as well.

Changes since REVIEWv3:

- Split off the pwc patch into the buf_finish return type change and
  the patch that only decompresses the image if the buffer state is
  DONE.

- Extend the comments in patch 07/18: explain that the buf_finish call in
  queue_cancel shouldn't be moved to __vb2_dqbuf, or we'll get the same
  bug that I introduced in an earlier version of this patch series.

The actual code has been unchanged since v3.

If there are no more comments, then I'll plan on making a pull request on
Friday.

Regards,

	Hans

[REVIEWv4 PATCH 01/18] vb2: Check if there are buffers before streamon

[Hans Verkuil]

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

This patch adds a test preventing streamon() if there is no buffer
ready.

Without this patch, a user could call streamon() before
preparing any buffer. This leads to a situation where if he calls
close() before calling streamoff() the device is kept streaming.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 5a5fb7f..a127925 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1776,6 +1776,11 @@ static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
 		return 0;
 	}
 
+	if (!q->num_buffers) {
+		dprintk(1, "streamon: no buffers have been allocated\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * If any buffers were queued before streamon,
 	 * we can now pass them to driver for processing.
-- 
1.9.0

[REVIEWv4 PATCH 02/18] vb2: fix read/write regression

[Hans Verkuil]

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

Commit 88e268702bfba78448abd20a31129458707383aa ("vb2: Improve file I/O
emulation to handle buffers in any order") broke read/write support if
the size of the buffer being read/written is less than the size of the
image.

When the commit was tested originally I used qv4l2, which calls read()
with exactly the size of the image. But if you try 'cat /dev/video0'
then it will fail and typically hang after reading two buffers.

This patch fixes the behavior by adding a new cur_index field that
contains the index of the field currently being filled/read, or it
is num_buffers in which case a new buffer needs to be dequeued.

The old index field has been renamed to initial_index in order to be
a bit more descriptive.

This has been tested with both read and write.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Andy Walls <awalls@md.metrocast.net>
---
 drivers/media/v4l2-core/videobuf2-core.c | 46 +++++++++++++++++++++++++++-----
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index a127925..f1a2857c 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2251,6 +2251,22 @@ struct vb2_fileio_buf {
 /**
  * struct vb2_fileio_data - queue context used by file io emulator
  *
+ * @cur_index:	the index of the buffer currently being read from or
+ *		written to. If equal to q->num_buffers then a new buffer
+ *		must be dequeued.
+ * @initial_index: in the read() case all buffers are queued up immediately
+ *		in __vb2_init_fileio() and __vb2_perform_fileio() just cycles
+ *		buffers. However, in the write() case no buffers are initially
+ *		queued, instead whenever a buffer is full it is queued up by
+ *		__vb2_perform_fileio(). Only once all available buffers have
+ *		been queued up will __vb2_perform_fileio() start to dequeue
+ *		buffers. This means that initially __vb2_perform_fileio()
+ *		needs to know what buffer index to use when it is queuing up
+ *		the buffers for the first time. That initial index is stored
+ *		in this field. Once it is equal to q->num_buffers all
+ *		available buffers have been queued and __vb2_perform_fileio()
+ *		should start the normal dequeue/queue cycle.
+ *
  * vb2 provides a compatibility layer and emulator of file io (read and
  * write) calls on top of streaming API. For proper operation it required
  * this structure to save the driver state between each call of the read
@@ -2260,7 +2276,8 @@ struct vb2_fileio_data {
 	struct v4l2_requestbuffers req;
 	struct v4l2_buffer b;
 	struct vb2_fileio_buf bufs[VIDEO_MAX_FRAME];
-	unsigned int index;
+	unsigned int cur_index;
+	unsigned int initial_index;
 	unsigned int q_count;
 	unsigned int dq_count;
 	unsigned int flags;
@@ -2360,7 +2377,12 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
 				goto err_reqbufs;
 			fileio->bufs[i].queued = 1;
 		}
-		fileio->index = q->num_buffers;
+		/*
+		 * All buffers have been queued, so mark that by setting
+		 * initial_index to q->num_buffers
+		 */
+		fileio->initial_index = q->num_buffers;
+		fileio->cur_index = q->num_buffers;
 	}
 
 	/*
@@ -2439,7 +2461,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
 	/*
 	 * Check if we need to dequeue the buffer.
 	 */
-	index = fileio->index;
+	index = fileio->cur_index;
 	if (index >= q->num_buffers) {
 		/*
 		 * Call vb2_dqbuf to get buffer back.
@@ -2453,7 +2475,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
 			return ret;
 		fileio->dq_count += 1;
 
-		index = fileio->b.index;
+		fileio->cur_index = index = fileio->b.index;
 		buf = &fileio->bufs[index];
 
 		/*
@@ -2529,8 +2551,20 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
 		buf->queued = 1;
 		buf->size = vb2_plane_size(q->bufs[index], 0);
 		fileio->q_count += 1;
-		if (fileio->index < q->num_buffers)
-			fileio->index++;
+		/*
+		 * If we are queuing up buffers for the first time, then
+		 * increase initial_index by one.
+		 */
+		if (fileio->initial_index < q->num_buffers)
+			fileio->initial_index++;
+		/*
+		 * The next buffer to use is either a buffer that's going to be
+		 * queued for the first time (initial_index < q->num_buffers)
+		 * or it is equal to q->num_buffers, meaning that the next
+		 * time we need to dequeue a buffer since we've now queued up
+		 * all the 'first time' buffers.
+		 */
+		fileio->cur_index = fileio->initial_index;
 	}
 
 	/*
-- 
1.9.0

[REVIEWv4 PATCH 03/18] vb2: fix PREPARE_BUF regression

[Hans Verkuil]

Fix an incorrect test in vb2_internal_qbuf() where only DEQUEUED buffers
are allowed. But PREPARED buffers are also OK.

Introduced by commit 4138111a27859dcc56a5592c804dd16bb12a23d1
("vb2: simplify qbuf/prepare_buf by removing callback").

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index f1a2857c..909f367 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1420,11 +1420,6 @@ static int vb2_internal_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
 		return ret;
 
 	vb = q->bufs[b->index];
-	if (vb->state != VB2_BUF_STATE_DEQUEUED) {
-		dprintk(1, "%s(): invalid buffer state %d\n", __func__,
-			vb->state);
-		return -EINVAL;
-	}
 
 	switch (vb->state) {
 	case VB2_BUF_STATE_DEQUEUED:
@@ -1438,7 +1433,8 @@ static int vb2_internal_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
 		dprintk(1, "qbuf: buffer still being prepared\n");
 		return -EINVAL;
 	default:
-		dprintk(1, "qbuf: buffer already in use\n");
+		dprintk(1, "%s(): invalid buffer state %d\n", __func__,
+			vb->state);
 		return -EINVAL;
 	}
 
-- 
1.9.0

[REVIEWv4 PATCH 04/18] vb2: add debugging code to check for unbalanced ops

[Hans Verkuil]

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>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.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 909f367..8f1578b 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
@@ -1635,7 +1765,7 @@ 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;
 		}
 }
@@ -1653,7 +1783,7 @@ 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;
@@ -1946,10 +2076,11 @@ 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;
 	}
 
@@ -2041,9 +2172,11 @@ 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);
-- 
1.9.0

[REVIEWv4 PATCH 05/18] vb2: change result code of buf_finish to void

[Hans Verkuil]

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

The buf_finish op should always work, so change the return type to void.
Update the few drivers that use it.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Reviewed-by: Pawel Osciak <pawel@osciak.com>
---
 drivers/media/parport/bw-qcam.c                 | 3 +--
 drivers/media/pci/sta2x11/sta2x11_vip.c         | 4 +---
 drivers/media/platform/marvell-ccic/mcam-core.c | 3 +--
 drivers/media/usb/pwc/pwc-if.c                  | 4 ++--
 drivers/media/usb/uvc/uvc_queue.c               | 3 +--
 drivers/media/v4l2-core/videobuf2-core.c        | 6 +-----
 drivers/staging/media/go7007/go7007-v4l2.c      | 3 +--
 include/media/videobuf2-core.h                  | 2 +-
 8 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/drivers/media/parport/bw-qcam.c b/drivers/media/parport/bw-qcam.c
index d12bd33..0166aef 100644
--- a/drivers/media/parport/bw-qcam.c
+++ b/drivers/media/parport/bw-qcam.c
@@ -667,7 +667,7 @@ static void buffer_queue(struct vb2_buffer *vb)
 	vb2_buffer_done(vb, VB2_BUF_STATE_DONE);
 }
 
-static int buffer_finish(struct vb2_buffer *vb)
+static void buffer_finish(struct vb2_buffer *vb)
 {
 	struct qcam *qcam = vb2_get_drv_priv(vb->vb2_queue);
 	void *vbuf = vb2_plane_vaddr(vb, 0);
@@ -691,7 +691,6 @@ static int buffer_finish(struct vb2_buffer *vb)
 	if (len != size)
 		vb->state = VB2_BUF_STATE_ERROR;
 	vb2_set_plane_payload(vb, 0, len);
-	return 0;
 }
 
 static struct vb2_ops qcam_video_qops = {
diff --git a/drivers/media/pci/sta2x11/sta2x11_vip.c b/drivers/media/pci/sta2x11/sta2x11_vip.c
index e5cfb6c..e66556c 100644
--- a/drivers/media/pci/sta2x11/sta2x11_vip.c
+++ b/drivers/media/pci/sta2x11/sta2x11_vip.c
@@ -327,7 +327,7 @@ static void buffer_queue(struct vb2_buffer *vb)
 	}
 	spin_unlock(&vip->lock);
 }
-static int buffer_finish(struct vb2_buffer *vb)
+static void buffer_finish(struct vb2_buffer *vb)
 {
 	struct sta2x11_vip *vip = vb2_get_drv_priv(vb->vb2_queue);
 	struct vip_buffer *vip_buf = to_vip_buffer(vb);
@@ -338,8 +338,6 @@ static int buffer_finish(struct vb2_buffer *vb)
 	spin_unlock(&vip->lock);
 
 	vip_active_buf_next(vip);
-
-	return 0;
 }
 
 static int start_streaming(struct vb2_queue *vq, unsigned int count)
diff --git a/drivers/media/platform/marvell-ccic/mcam-core.c b/drivers/media/platform/marvell-ccic/mcam-core.c
index 32fab30..8b34c48 100644
--- a/drivers/media/platform/marvell-ccic/mcam-core.c
+++ b/drivers/media/platform/marvell-ccic/mcam-core.c
@@ -1238,7 +1238,7 @@ static int mcam_vb_sg_buf_prepare(struct vb2_buffer *vb)
 	return 0;
 }
 
-static int mcam_vb_sg_buf_finish(struct vb2_buffer *vb)
+static void mcam_vb_sg_buf_finish(struct vb2_buffer *vb)
 {
 	struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
 	struct sg_table *sg_table = vb2_dma_sg_plane_desc(vb, 0);
@@ -1246,7 +1246,6 @@ static int mcam_vb_sg_buf_finish(struct vb2_buffer *vb)
 	if (sg_table)
 		dma_unmap_sg(cam->dev, sg_table->sgl,
 				sg_table->nents, DMA_FROM_DEVICE);
-	return 0;
 }
 
 static void mcam_vb_sg_buf_cleanup(struct vb2_buffer *vb)
diff --git a/drivers/media/usb/pwc/pwc-if.c b/drivers/media/usb/pwc/pwc-if.c
index abf365a..619121f 100644
--- a/drivers/media/usb/pwc/pwc-if.c
+++ b/drivers/media/usb/pwc/pwc-if.c
@@ -614,7 +614,7 @@ static int buffer_prepare(struct vb2_buffer *vb)
 	return 0;
 }
 
-static int buffer_finish(struct vb2_buffer *vb)
+static void buffer_finish(struct vb2_buffer *vb)
 {
 	struct pwc_device *pdev = vb2_get_drv_priv(vb->vb2_queue);
 	struct pwc_frame_buf *buf = container_of(vb, struct pwc_frame_buf, vb);
@@ -624,7 +624,7 @@ static int buffer_finish(struct vb2_buffer *vb)
 	 * filled, take the pwc data we've stored in buf->data and decompress
 	 * it into a usable format, storing the result in the vb2_buffer
 	 */
-	return pwc_decompress(pdev, buf);
+	pwc_decompress(pdev, buf);
 }
 
 static void buffer_cleanup(struct vb2_buffer *vb)
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index cd962be..cca2c6e 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -104,7 +104,7 @@ static void uvc_buffer_queue(struct vb2_buffer *vb)
 	spin_unlock_irqrestore(&queue->irqlock, flags);
 }
 
-static int uvc_buffer_finish(struct vb2_buffer *vb)
+static void uvc_buffer_finish(struct vb2_buffer *vb)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
 	struct uvc_streaming *stream =
@@ -112,7 +112,6 @@ static int uvc_buffer_finish(struct vb2_buffer *vb)
 	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
 
 	uvc_video_clock_update(stream, &vb->v4l2_buf, buf);
-	return 0;
 }
 
 static void uvc_wait_prepare(struct vb2_queue *vq)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 8f1578b..59bfd85 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1783,11 +1783,7 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
 	if (ret < 0)
 		return ret;
 
-	ret = call_vb_qop(vb, buf_finish, vb);
-	if (ret) {
-		dprintk(1, "dqbuf: buffer finish failed\n");
-		return ret;
-	}
+	call_vb_qop(vb, buf_finish, vb);
 
 	switch (vb->state) {
 	case VB2_BUF_STATE_DONE:
diff --git a/drivers/staging/media/go7007/go7007-v4l2.c b/drivers/staging/media/go7007/go7007-v4l2.c
index edc52e2..3a01576 100644
--- a/drivers/staging/media/go7007/go7007-v4l2.c
+++ b/drivers/staging/media/go7007/go7007-v4l2.c
@@ -470,7 +470,7 @@ static int go7007_buf_prepare(struct vb2_buffer *vb)
 	return 0;
 }
 
-static int go7007_buf_finish(struct vb2_buffer *vb)
+static void go7007_buf_finish(struct vb2_buffer *vb)
 {
 	struct vb2_queue *vq = vb->vb2_queue;
 	struct go7007 *go = vb2_get_drv_priv(vq);
@@ -483,7 +483,6 @@ static int go7007_buf_finish(struct vb2_buffer *vb)
 			V4L2_BUF_FLAG_PFRAME);
 	buf->flags |= frame_type_flag;
 	buf->field = V4L2_FIELD_NONE;
-	return 0;
 }
 
 static int go7007_start_streaming(struct vb2_queue *q, unsigned int count)
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index f04eb28..f443ce0 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -311,7 +311,7 @@ struct vb2_ops {
 
 	int (*buf_init)(struct vb2_buffer *vb);
 	int (*buf_prepare)(struct vb2_buffer *vb);
-	int (*buf_finish)(struct vb2_buffer *vb);
+	void (*buf_finish)(struct vb2_buffer *vb);
 	void (*buf_cleanup)(struct vb2_buffer *vb);
 
 	int (*start_streaming)(struct vb2_queue *q, unsigned int count);
-- 
1.9.0

[REVIEWv4 PATCH 06/18] pwc: do not decompress the image unless the state is DONE

[Hans Verkuil]

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

There is no point in trying to decompress a captured frame unless
the buffer state is OK. It won't be used in any other state, and
in fact the contents of the buffer might well be corrupt.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/usb/pwc/pwc-if.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/media/usb/pwc/pwc-if.c b/drivers/media/usb/pwc/pwc-if.c
index 619121f..d13e7c9 100644
--- a/drivers/media/usb/pwc/pwc-if.c
+++ b/drivers/media/usb/pwc/pwc-if.c
@@ -619,12 +619,15 @@ static void buffer_finish(struct vb2_buffer *vb)
 	struct pwc_device *pdev = vb2_get_drv_priv(vb->vb2_queue);
 	struct pwc_frame_buf *buf = container_of(vb, struct pwc_frame_buf, vb);
 
-	/*
-	 * Application has called dqbuf and is getting back a buffer we've
-	 * filled, take the pwc data we've stored in buf->data and decompress
-	 * it into a usable format, storing the result in the vb2_buffer
-	 */
-	pwc_decompress(pdev, buf);
+	if (vb->state == VB2_BUF_STATE_DONE) {
+		/*
+		 * Application has called dqbuf and is getting back a buffer
+		 * we've filled, take the pwc data we've stored in buf->data
+		 * and decompress it into a usable format, storing the result
+		 * in the vb2_buffer.
+		 */
+		pwc_decompress(pdev, buf);
+	}
 }
 
 static void buffer_cleanup(struct vb2_buffer *vb)
-- 
1.9.0

[REVIEWv4 PATCH 07/18] vb2: call buf_finish from __queue_cancel.

[Hans Verkuil]

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

If a queue was canceled, then the buf_finish op was never called for the
pending buffers. So add this call to queue_cancel. Before calling buf_finish
set the buffer state to PREPARED, which is the correct state. That way the
states DONE and ERROR will only be seen in buf_finish if streaming is in
progress.

Since buf_finish can now be called from non-streaming state we need to
adapt the handful of drivers that actually need to know this.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/parport/bw-qcam.c          |  3 +++
 drivers/media/pci/sta2x11/sta2x11_vip.c  |  3 ++-
 drivers/media/usb/uvc/uvc_queue.c        |  3 ++-
 drivers/media/v4l2-core/videobuf2-core.c | 17 +++++++++++++++--
 include/media/videobuf2-core.h           | 10 +++++++++-
 5 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/media/parport/bw-qcam.c b/drivers/media/parport/bw-qcam.c
index 0166aef..8d69bfb 100644
--- a/drivers/media/parport/bw-qcam.c
+++ b/drivers/media/parport/bw-qcam.c
@@ -674,6 +674,9 @@ static void buffer_finish(struct vb2_buffer *vb)
 	int size = vb->vb2_queue->plane_sizes[0];
 	int len;
 
+	if (!vb2_is_streaming(vb->vb2_queue))
+		return;
+
 	mutex_lock(&qcam->lock);
 	parport_claim_or_block(qcam->pdev);
 
diff --git a/drivers/media/pci/sta2x11/sta2x11_vip.c b/drivers/media/pci/sta2x11/sta2x11_vip.c
index e66556c..bb11443 100644
--- a/drivers/media/pci/sta2x11/sta2x11_vip.c
+++ b/drivers/media/pci/sta2x11/sta2x11_vip.c
@@ -337,7 +337,8 @@ static void buffer_finish(struct vb2_buffer *vb)
 	list_del_init(&vip_buf->list);
 	spin_unlock(&vip->lock);
 
-	vip_active_buf_next(vip);
+	if (vb2_is_streaming(vb->vb2_queue))
+		vip_active_buf_next(vip);
 }
 
 static int start_streaming(struct vb2_queue *vq, unsigned int count)
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index cca2c6e..ab9f96e 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -111,7 +111,8 @@ static void uvc_buffer_finish(struct vb2_buffer *vb)
 			container_of(queue, struct uvc_streaming, queue);
 	struct uvc_buffer *buf = container_of(vb, struct uvc_buffer, buf);
 
-	uvc_video_clock_update(stream, &vb->v4l2_buf, buf);
+	if (vb->state == VB2_BUF_STATE_DONE)
+		uvc_video_clock_update(stream, &vb->v4l2_buf, buf);
 }
 
 static void uvc_wait_prepare(struct vb2_queue *vq)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 59bfd85..f42520b 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1878,9 +1878,22 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
 
 	/*
 	 * Reinitialize all buffers for next use.
+	 * Make sure to call buf_finish for any queued buffers. Normally
+	 * that's done in dqbuf, but that's not going to happen when we
+	 * cancel the whole queue. Note: this code belongs here, not in
+	 * __vb2_dqbuf() since in vb2_internal_dqbuf() there is a critical
+	 * call to __fill_v4l2_buffer() after buf_finish(). That order can't
+	 * be changed, so we can't move the buf_finish() to __vb2_dqbuf().
 	 */
-	for (i = 0; i < q->num_buffers; ++i)
-		__vb2_dqbuf(q->bufs[i]);
+	for (i = 0; i < q->num_buffers; ++i) {
+		struct vb2_buffer *vb = q->bufs[i];
+
+		if (vb->state != VB2_BUF_STATE_DEQUEUED) {
+			vb->state = VB2_BUF_STATE_PREPARED;
+			call_vb_qop(vb, buf_finish, vb);
+		}
+		__vb2_dqbuf(vb);
+	}
 }
 
 static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index f443ce0..3cb0bcf 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -276,7 +276,15 @@ struct vb2_buffer {
  *			in driver; optional
  * @buf_finish:		called before every dequeue of the buffer back to
  *			userspace; drivers may perform any operations required
- *			before userspace accesses the buffer; optional
+ *			before userspace accesses the buffer; optional. The
+ *			buffer state can be one of the following: DONE and
+ *			ERROR occur while streaming is in progress, and the
+ *			PREPARED state occurs when the queue has been canceled
+ *			and all pending buffers are being returned to their
+ *			default DEQUEUED state. Typically you only have to do
+ *			something if the state is VB2_BUF_STATE_DONE, since in
+ *			all other cases the buffer contents will be ignored
+ *			anyway.
  * @buf_cleanup:	called once before the buffer is freed; drivers may
  *			perform any additional cleanup; optional
  * @start_streaming:	called once to enter 'streaming' state; the driver may
-- 
1.9.0

[REVIEWv4 PATCH 08/18] vb2: consistent usage of periods in videobuf2-core.h

[Hans Verkuil]

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

Sometimes sentences in comments ended with a period, and sometimes they
didn't. Add periods. No other changes.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 include/media/videobuf2-core.h | 40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 3cb0bcf..06efa4a 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -34,49 +34,49 @@ struct vb2_fileio_data;
  *		usually will result in the allocator freeing the buffer (if
  *		no other users of this buffer are present); the buf_priv
  *		argument is the allocator private per-buffer structure
- *		previously returned from the alloc callback
+ *		previously returned from the alloc callback.
  * @get_userptr: acquire userspace memory for a hardware operation; used for
  *		 USERPTR memory types; vaddr is the address passed to the
  *		 videobuf layer when queuing a video buffer of USERPTR type;
  *		 should return an allocator private per-buffer structure
  *		 associated with the buffer on success, NULL on failure;
  *		 the returned private structure will then be passed as buf_priv
- *		 argument to other ops in this structure
+ *		 argument to other ops in this structure.
  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
- *		 be used
+ *		 be used.
  * @attach_dmabuf: attach a shared struct dma_buf for a hardware operation;
  *		   used for DMABUF memory types; alloc_ctx is the alloc context
  *		   dbuf is the shared dma_buf; returns NULL on failure;
  *		   allocator private per-buffer structure on success;
- *		   this needs to be used for further accesses to the buffer
+ *		   this needs to be used for further accesses to the buffer.
  * @detach_dmabuf: inform the exporter of the buffer that the current DMABUF
  *		   buffer is no longer used; the buf_priv argument is the
  *		   allocator private per-buffer structure previously returned
- *		   from the attach_dmabuf callback
+ *		   from the attach_dmabuf callback.
  * @map_dmabuf: request for access to the dmabuf from allocator; the allocator
  *		of dmabuf is informed that this driver is going to use the
- *		dmabuf
+ *		dmabuf.
  * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified
- *		  that this driver is done using the dmabuf for now
+ *		  that this driver is done using the dmabuf for now.
  * @prepare:	called every time the buffer is passed from userspace to the
- *		driver, useful for cache synchronisation, optional
+ *		driver, useful for cache synchronisation, optional.
  * @finish:	called every time the buffer is passed back from the driver
- *		to the userspace, also optional
+ *		to the userspace, also optional.
  * @vaddr:	return a kernel virtual address to a given memory buffer
  *		associated with the passed private structure or NULL if no
- *		such mapping exists
+ *		such mapping exists.
  * @cookie:	return allocator specific cookie for a given memory buffer
  *		associated with the passed private structure or NULL if not
- *		available
+ *		available.
  * @num_users:	return the current number of users of a memory buffer;
  *		return 1 if the videobuf layer (or actually the driver using
- *		it) is the only user
+ *		it) is the only user.
  * @mmap:	setup a userspace mapping for a given memory buffer under
- *		the provided virtual memory region
+ *		the provided virtual memory region.
  *
  * Required ops for USERPTR types: get_userptr, put_userptr.
  * Required ops for MMAP types: alloc, put, num_users, mmap.
- * Required ops for read/write access types: alloc, put, num_users, vaddr
+ * Required ops for read/write access types: alloc, put, num_users, vaddr.
  * Required ops for DMABUF types: attach_dmabuf, detach_dmabuf, map_dmabuf,
  *				  unmap_dmabuf.
  */
@@ -258,22 +258,22 @@ struct vb2_buffer {
  * @wait_prepare:	release any locks taken while calling vb2 functions;
  *			it is called before an ioctl needs to wait for a new
  *			buffer to arrive; required to avoid a deadlock in
- *			blocking access type
+ *			blocking access type.
  * @wait_finish:	reacquire all locks released in the previous callback;
  *			required to continue operation after sleeping while
- *			waiting for a new buffer to arrive
+ *			waiting for a new buffer to arrive.
  * @buf_init:		called once after allocating a buffer (in MMAP case)
  *			or after acquiring a new USERPTR buffer; drivers may
  *			perform additional buffer-related initialization;
  *			initialization failure (return != 0) will prevent
- *			queue setup from completing successfully; optional
+ *			queue setup from completing successfully; optional.
  * @buf_prepare:	called every time the buffer is queued from userspace
  *			and from the VIDIOC_PREPARE_BUF ioctl; drivers may
  *			perform any initialization required before each hardware
  *			operation in this callback; drivers that support
  *			VIDIOC_CREATE_BUFS must also validate the buffer size;
  *			if an error is returned, the buffer will not be queued
- *			in driver; optional
+ *			in driver; optional.
  * @buf_finish:		called before every dequeue of the buffer back to
  *			userspace; drivers may perform any operations required
  *			before userspace accesses the buffer; optional. The
@@ -286,7 +286,7 @@ struct vb2_buffer {
  *			all other cases the buffer contents will be ignored
  *			anyway.
  * @buf_cleanup:	called once before the buffer is freed; drivers may
- *			perform any additional cleanup; optional
+ *			perform any additional cleanup; optional.
  * @start_streaming:	called once to enter 'streaming' state; the driver may
  *			receive buffers with @buf_queue callback before
  *			@start_streaming is called; the driver gets the number
@@ -307,7 +307,7 @@ struct vb2_buffer {
  *			the buffer back by calling vb2_buffer_done() function;
  *			it is allways called after calling STREAMON ioctl;
  *			might be called before start_streaming callback if user
- *			pre-queued buffers before calling STREAMON
+ *			pre-queued buffers before calling STREAMON.
  */
 struct vb2_ops {
 	int (*queue_setup)(struct vb2_queue *q, const struct v4l2_format *fmt,
-- 
1.9.0

[REVIEWv4 PATCH 09/18] vb2: fix buf_init/buf_cleanup call sequences

[Hans Verkuil]

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

Ensure that these ops are properly balanced.

There are two scenarios:

1) for MMAP buf_init is called when the buffers are created and buf_cleanup
   must be called when the queue is finally freed. This scenario was always
   working.

2) for USERPTR and DMABUF it is more complicated. When a buffer is queued
   the code checks if all planes of this buffer have been acquired before.
   If that's the case, then only buf_prepare has to be called. Otherwise
   buf_cleanup needs to be called if the buffer was acquired before, then,
   once all changed planes have been (re)acquired, buf_init has to be
   called followed by buf_prepare. Should buf_prepare fail, then buf_cleanup
   must be called on the newly acquired planes to release them in.

Finally, in __vb2_queue_free we have to check if the buffer was actually
acquired before calling buf_cleanup. While that it always true for MMAP
mode, it is not necessarily true for the other modes. E.g. if you just
call REQBUFS and close the file handle, then buffers were never queued and
so no buf_init was ever called.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 100 +++++++++++++++++++++----------
 1 file changed, 67 insertions(+), 33 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index f42520b..7753abe 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -373,8 +373,10 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 	/* Call driver-provided cleanup function for each buffer, if provided */
 	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]);
+		struct vb2_buffer *vb = q->bufs[buffer];
+
+		if (vb && vb->planes[0].mem_priv)
+			call_vb_qop(vb, buf_cleanup, vb);
 	}
 
 	/* Release video buffer memory */
@@ -1161,6 +1163,7 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	unsigned int plane;
 	int ret;
 	int write = !V4L2_TYPE_IS_OUTPUT(q->type);
+	bool reacquired = vb->planes[0].mem_priv == NULL;
 
 	/* Copy relevant information provided by the userspace */
 	__fill_vb2_buffer(vb, b, planes);
@@ -1186,12 +1189,16 @@ 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)
+		if (vb->planes[plane].mem_priv) {
+			if (!reacquired) {
+				reacquired = true;
+				call_vb_qop(vb, buf_cleanup, vb);
+			}
 			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;
+		memset(&vb->v4l2_planes[plane], 0, sizeof(struct v4l2_plane));
 
 		/* Acquire each plane's memory */
 		mem_priv = call_memop(vb, get_userptr, q->alloc_ctx[plane],
@@ -1208,23 +1215,34 @@ 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_vb_qop(vb, buf_init, vb);
-	if (ret) {
-		dprintk(1, "qbuf: buffer initialization failed\n");
-		fail_vb_qop(vb, buf_init);
-		goto err;
-	}
-
-	/*
 	 * Now that everything is in order, copy relevant information
 	 * provided by userspace.
 	 */
 	for (plane = 0; plane < vb->num_planes; ++plane)
 		vb->v4l2_planes[plane] = planes[plane];
 
+	if (reacquired) {
+		/*
+		 * One or more planes changed, so we must call buf_init to do
+		 * the driver-specific initialization on the newly acquired
+		 * buffer, if provided.
+		 */
+		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;
+		}
+	}
+
+	ret = call_vb_qop(vb, buf_prepare, vb);
+	if (ret) {
+		dprintk(1, "qbuf: buffer preparation failed\n");
+		fail_vb_qop(vb, buf_prepare);
+		call_vb_qop(vb, buf_cleanup, vb);
+		goto err;
+	}
+
 	return 0;
 err:
 	/* In case of errors, release planes that were already acquired */
@@ -1244,8 +1262,13 @@ err:
  */
 static int __qbuf_mmap(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 {
+	int ret;
+
 	__fill_vb2_buffer(vb, b, vb->v4l2_planes);
-	return 0;
+	ret = call_vb_qop(vb, buf_prepare, vb);
+	if (ret)
+		fail_vb_qop(vb, buf_prepare);
+	return ret;
 }
 
 /**
@@ -1259,6 +1282,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 	unsigned int plane;
 	int ret;
 	int write = !V4L2_TYPE_IS_OUTPUT(q->type);
+	bool reacquired = vb->planes[0].mem_priv == NULL;
 
 	/* Copy relevant information provided by the userspace */
 	__fill_vb2_buffer(vb, b, planes);
@@ -1294,6 +1318,11 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 
 		dprintk(1, "qbuf: buffer for plane %d changed\n", plane);
 
+		if (!reacquired) {
+			reacquired = true;
+			call_vb_qop(vb, buf_cleanup, vb);
+		}
+
 		/* Release previously acquired memory if present */
 		__vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
 		memset(&vb->v4l2_planes[plane], 0, sizeof(struct v4l2_plane));
@@ -1329,23 +1358,33 @@ 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_vb_qop(vb, buf_init, vb);
-	if (ret) {
-		dprintk(1, "qbuf: buffer initialization failed\n");
-		fail_vb_qop(vb, buf_init);
-		goto err;
-	}
-
-	/*
 	 * Now that everything is in order, copy relevant information
 	 * provided by userspace.
 	 */
 	for (plane = 0; plane < vb->num_planes; ++plane)
 		vb->v4l2_planes[plane] = planes[plane];
 
+	if (reacquired) {
+		/*
+		 * Call driver-specific initialization on the newly acquired buffer,
+		 * if provided.
+		 */
+		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;
+		}
+	}
+
+	ret = call_vb_qop(vb, buf_prepare, vb);
+	if (ret) {
+		dprintk(1, "qbuf: buffer preparation failed\n");
+		fail_vb_qop(vb, buf_prepare);
+		call_vb_qop(vb, buf_cleanup, vb);
+		goto err;
+	}
+
 	return 0;
 err:
 	/* In case of errors, release planes that were already acquired */
@@ -1420,11 +1459,6 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 		ret = -EINVAL;
 	}
 
-	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;
-- 
1.9.0

[REVIEWv4 PATCH 10/18] vb2: rename queued_count to owned_by_drv_count

[Hans Verkuil]

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

'queued_count' is a bit vague since it is not clear to which queue it
refers to: the vb2 internal list of buffers or the driver-owned list
of buffers.

Rename to make it explicit.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 10 +++++-----
 include/media/videobuf2-core.h           |  4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 7753abe..018a132 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1071,7 +1071,7 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 	spin_lock_irqsave(&q->done_lock, flags);
 	vb->state = state;
 	list_add_tail(&vb->done_entry, &q->done_list);
-	atomic_dec(&q->queued_count);
+	atomic_dec(&q->owned_by_drv_count);
 	spin_unlock_irqrestore(&q->done_lock, flags);
 
 	/* Inform any processes that may be waiting for buffers */
@@ -1402,7 +1402,7 @@ static void __enqueue_in_driver(struct vb2_buffer *vb)
 	unsigned int plane;
 
 	vb->state = VB2_BUF_STATE_ACTIVE;
-	atomic_inc(&q->queued_count);
+	atomic_inc(&q->owned_by_drv_count);
 
 	/* sync buffers */
 	for (plane = 0; plane < vb->num_planes; ++plane)
@@ -1554,7 +1554,7 @@ static int vb2_start_streaming(struct vb2_queue *q)
 	int ret;
 
 	/* Tell the driver to start streaming */
-	ret = call_qop(q, start_streaming, q, atomic_read(&q->queued_count));
+	ret = call_qop(q, start_streaming, q, atomic_read(&q->owned_by_drv_count));
 	if (ret)
 		fail_qop(q, start_streaming);
 
@@ -1775,7 +1775,7 @@ int vb2_wait_for_all_buffers(struct vb2_queue *q)
 	}
 
 	if (!q->retry_start_streaming)
-		wait_event(q->done_wq, !atomic_read(&q->queued_count));
+		wait_event(q->done_wq, !atomic_read(&q->owned_by_drv_count));
 	return 0;
 }
 EXPORT_SYMBOL_GPL(vb2_wait_for_all_buffers);
@@ -1907,7 +1907,7 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
 	 * has not already dequeued before initiating cancel.
 	 */
 	INIT_LIST_HEAD(&q->done_list);
-	atomic_set(&q->queued_count, 0);
+	atomic_set(&q->owned_by_drv_count, 0);
 	wake_up_all(&q->done_wq);
 
 	/*
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 06efa4a..4f8dce2 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -359,7 +359,7 @@ struct v4l2_fh;
  * @bufs:	videobuf buffer structures
  * @num_buffers: number of allocated/used buffers
  * @queued_list: list of buffers currently queued from userspace
- * @queued_count: number of buffers owned by the driver
+ * @owned_by_drv_count: number of buffers owned by the driver
  * @done_list:	list of buffers ready to be dequeued to userspace
  * @done_lock:	lock to protect done_list list
  * @done_wq:	waitqueue for processes waiting for buffers ready to be dequeued
@@ -391,7 +391,7 @@ struct vb2_queue {
 
 	struct list_head		queued_list;
 
-	atomic_t			queued_count;
+	atomic_t			owned_by_drv_count;
 	struct list_head		done_list;
 	spinlock_t			done_lock;
 	wait_queue_head_t		done_wq;
-- 
1.9.0

[REVIEWv4 PATCH 11/18] vb2: don't init the list if there are still buffers

[Hans Verkuil]

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

__vb2_queue_free() would init the queued_list at all times, even if
q->num_buffers > 0. This should only happen if num_buffers == 0.

This situation can happen if a CREATE_BUFFERS call couldn't allocate
enough buffers and had to free those it did manage to allocate before
returning an error.

While we're at it: __vb2_queue_alloc() returns the number of buffers
allocated, not an error code. So stick the result in allocated_buffers
instead of ret as that's very confusing.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 018a132..07cce7f 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -452,9 +452,10 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 	}
 
 	q->num_buffers -= buffers;
-	if (!q->num_buffers)
+	if (!q->num_buffers) {
 		q->memory = 0;
-	INIT_LIST_HEAD(&q->queued_list);
+		INIT_LIST_HEAD(&q->queued_list);
+	}
 	return 0;
 }
 
@@ -820,14 +821,12 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	}
 
 	/* Finally, allocate buffers and video memory */
-	ret = __vb2_queue_alloc(q, req->memory, num_buffers, num_planes);
-	if (ret == 0) {
+	allocated_buffers = __vb2_queue_alloc(q, req->memory, num_buffers, num_planes);
+	if (allocated_buffers == 0) {
 		dprintk(1, "Memory allocation failed\n");
 		return -ENOMEM;
 	}
 
-	allocated_buffers = ret;
-
 	/*
 	 * Check if driver can handle the allocated number of buffers.
 	 */
@@ -851,6 +850,10 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	q->num_buffers = allocated_buffers;
 
 	if (ret < 0) {
+		/*
+		 * Note: __vb2_queue_free() will subtract 'allocated_buffers'
+		 * from q->num_buffers.
+		 */
 		__vb2_queue_free(q, allocated_buffers);
 		return ret;
 	}
@@ -924,20 +927,18 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
 	}
 
 	/* Finally, allocate buffers and video memory */
-	ret = __vb2_queue_alloc(q, create->memory, num_buffers,
+	allocated_buffers = __vb2_queue_alloc(q, create->memory, num_buffers,
 				num_planes);
-	if (ret == 0) {
+	if (allocated_buffers == 0) {
 		dprintk(1, "Memory allocation failed\n");
 		return -ENOMEM;
 	}
 
-	allocated_buffers = ret;
-
 	/*
 	 * Check if driver can handle the so far allocated number of buffers.
 	 */
-	if (ret < num_buffers) {
-		num_buffers = ret;
+	if (allocated_buffers < num_buffers) {
+		num_buffers = allocated_buffers;
 
 		/*
 		 * q->num_buffers contains the total number of buffers, that the
@@ -960,6 +961,10 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
 	q->num_buffers += allocated_buffers;
 
 	if (ret < 0) {
+		/*
+		 * Note: __vb2_queue_free() will subtract 'allocated_buffers'
+		 * from q->num_buffers.
+		 */
 		__vb2_queue_free(q, allocated_buffers);
 		return -ENOMEM;
 	}
-- 
1.9.0

[REVIEWv4 PATCH 12/18] vb2: only call start_streaming if sufficient buffers are queued

[Hans Verkuil]

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

In commit 02f142ecd24aaf891324ffba8527284c1731b561 support was added to
start_streaming to return -ENOBUFS if insufficient buffers were queued
for the DMA engine to start. The vb2 core would attempt calling
start_streaming again if another buffer would be queued up.

Later analysis uncovered problems with the queue management if start_streaming
would return an error: the buffers are enqueued to the driver before the
start_streaming op is called, so after an error they are never returned to
the vb2 core. The solution for this is to let the driver return them to
the vb2 core in case of an error while starting the DMA engine. However,
in the case of -ENOBUFS that would be weird: it is not a real error, it
just says that more buffers are needed. Requiring start_streaming to give
them back only to have them requeued again the next time the application
calls QBUF is inefficient.

This patch changes this mechanism: it adds a 'min_buffers_needed' field
to vb2_queue that drivers can set with the minimum number of buffers
required to start the DMA engine. The start_streaming op is only called
if enough buffers are queued. The -ENOBUFS handling has been dropped in
favor of this new method.

Drivers are expected to return buffers back to vb2 core with state QUEUED
if start_streaming would return an error. The vb2 core checks for this
and produces a warning if that didn't happen and it will forcefully
reclaim such buffers to ensure that the internal vb2 core state remains
consistent and all buffer-related resources have been correctly freed
and all op calls have been balanced.

__reqbufs() has been updated to check that at least min_buffers_needed
buffers could be allocated. If fewer buffers were allocated then __reqbufs
will free what was allocated and return -ENOMEM. Based on a suggestion from
Pawel Osciak.

__create_bufs() doesn't do that check, since the use of __create_bufs
assumes some advance scenario where the user might want more control.
Instead streamon will check if enough buffers were allocated to prevent
streaming with fewer than the minimum required number of buffers.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/platform/davinci/vpbe_display.c   |   6 +-
 drivers/media/platform/davinci/vpif_capture.c   |   7 +-
 drivers/media/platform/davinci/vpif_display.c   |   7 +-
 drivers/media/platform/s5p-tv/mixer_video.c     |   6 +-
 drivers/media/v4l2-core/videobuf2-core.c        | 146 ++++++++++++++++--------
 drivers/staging/media/davinci_vpfe/vpfe_video.c |   3 +-
 include/media/videobuf2-core.h                  |  14 ++-
 7 files changed, 116 insertions(+), 73 deletions(-)

diff --git a/drivers/media/platform/davinci/vpbe_display.c b/drivers/media/platform/davinci/vpbe_display.c
index b02aba4..9231e48 100644
--- a/drivers/media/platform/davinci/vpbe_display.c
+++ b/drivers/media/platform/davinci/vpbe_display.c
@@ -344,11 +344,6 @@ static int vpbe_start_streaming(struct vb2_queue *vq, unsigned int count)
 	struct vpbe_device *vpbe_dev = fh->disp_dev->vpbe_dev;
 	int ret;
 
-	/* If buffer queue is empty, return error */
-	if (list_empty(&layer->dma_queue)) {
-		v4l2_err(&vpbe_dev->v4l2_dev, "buffer queue is empty\n");
-		return -ENOBUFS;
-	}
 	/* Get the next frame from the buffer queue */
 	layer->next_frm = layer->cur_frm = list_entry(layer->dma_queue.next,
 				struct vpbe_disp_buffer, list);
@@ -1416,6 +1411,7 @@ static int vpbe_display_reqbufs(struct file *file, void *priv,
 	q->mem_ops = &vb2_dma_contig_memops;
 	q->buf_struct_size = sizeof(struct vpbe_disp_buffer);
 	q->timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+	q->min_buffers_needed = 1;
 
 	ret = vb2_queue_init(q);
 	if (ret) {
diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
index 735ec47..9731ad4 100644
--- a/drivers/media/platform/davinci/vpif_capture.c
+++ b/drivers/media/platform/davinci/vpif_capture.c
@@ -272,13 +272,7 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count)
 	unsigned long flags;
 	int ret;
 
-	/* If buffer queue is empty, return error */
 	spin_lock_irqsave(&common->irqlock, flags);
-	if (list_empty(&common->dma_queue)) {
-		spin_unlock_irqrestore(&common->irqlock, flags);
-		vpif_dbg(1, debug, "buffer queue is empty\n");
-		return -ENOBUFS;
-	}
 
 	/* Get the next frame from the buffer queue */
 	common->cur_frm = common->next_frm = list_entry(common->dma_queue.next,
@@ -1024,6 +1018,7 @@ static int vpif_reqbufs(struct file *file, void *priv,
 	q->mem_ops = &vb2_dma_contig_memops;
 	q->buf_struct_size = sizeof(struct vpif_cap_buffer);
 	q->timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+	q->min_buffers_needed = 1;
 
 	ret = vb2_queue_init(q);
 	if (ret) {
diff --git a/drivers/media/platform/davinci/vpif_display.c b/drivers/media/platform/davinci/vpif_display.c
index 9d115cd..af660f5 100644
--- a/drivers/media/platform/davinci/vpif_display.c
+++ b/drivers/media/platform/davinci/vpif_display.c
@@ -234,13 +234,7 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count)
 	unsigned long flags;
 	int ret;
 
-	/* If buffer queue is empty, return error */
 	spin_lock_irqsave(&common->irqlock, flags);
-	if (list_empty(&common->dma_queue)) {
-		spin_unlock_irqrestore(&common->irqlock, flags);
-		vpif_err("buffer queue is empty\n");
-		return -ENOBUFS;
-	}
 
 	/* Get the next frame from the buffer queue */
 	common->next_frm = common->cur_frm =
@@ -984,6 +978,7 @@ static int vpif_reqbufs(struct file *file, void *priv,
 	q->mem_ops = &vb2_dma_contig_memops;
 	q->buf_struct_size = sizeof(struct vpif_disp_buffer);
 	q->timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+	q->min_buffers_needed = 1;
 
 	ret = vb2_queue_init(q);
 	if (ret) {
diff --git a/drivers/media/platform/s5p-tv/mixer_video.c b/drivers/media/platform/s5p-tv/mixer_video.c
index c5059ba..a1ce55f 100644
--- a/drivers/media/platform/s5p-tv/mixer_video.c
+++ b/drivers/media/platform/s5p-tv/mixer_video.c
@@ -946,11 +946,6 @@ static int start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	mxr_dbg(mdev, "%s\n", __func__);
 
-	if (count == 0) {
-		mxr_dbg(mdev, "no output buffers queued\n");
-		return -ENOBUFS;
-	}
-
 	/* block any changes in output configuration */
 	mxr_output_get(mdev);
 
@@ -1124,6 +1119,7 @@ struct mxr_layer *mxr_base_layer_create(struct mxr_device *mdev,
 		.drv_priv = layer,
 		.buf_struct_size = sizeof(struct mxr_buffer),
 		.ops = &mxr_video_qops,
+		.min_buffers_needed = 1,
 		.mem_ops = &vb2_dma_contig_memops,
 	};
 
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 07cce7f..1f6eccf 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -805,6 +805,7 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	 * Make sure the requested values and current defaults are sane.
 	 */
 	num_buffers = min_t(unsigned int, req->count, VIDEO_MAX_FRAME);
+	num_buffers = max_t(unsigned int, req->count, q->min_buffers_needed);
 	memset(q->plane_sizes, 0, sizeof(q->plane_sizes));
 	memset(q->alloc_ctx, 0, sizeof(q->alloc_ctx));
 	q->memory = req->memory;
@@ -828,9 +829,16 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 	}
 
 	/*
+	 * There is no point in continuing if we can't allocate the minimum
+	 * number of buffers needed by this vb2_queue.
+	 */
+	if (allocated_buffers < q->min_buffers_needed)
+		ret = -ENOMEM;
+
+	/*
 	 * Check if driver can handle the allocated number of buffers.
 	 */
-	if (allocated_buffers < num_buffers) {
+	if (!ret && allocated_buffers < num_buffers) {
 		num_buffers = allocated_buffers;
 
 		ret = call_qop(q, queue_setup, q, NULL, &num_buffers,
@@ -1038,13 +1046,20 @@ EXPORT_SYMBOL_GPL(vb2_plane_cookie);
  * vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
  * @vb:		vb2_buffer returned from the driver
  * @state:	either VB2_BUF_STATE_DONE if the operation finished successfully
- *		or VB2_BUF_STATE_ERROR if the operation finished with an error
+ *		or VB2_BUF_STATE_ERROR if the operation finished with an error.
+ *		If start_streaming fails then it should return buffers with state
+ *		VB2_BUF_STATE_QUEUED to put them back into the queue.
  *
  * This function should be called by the driver after a hardware operation on
  * a buffer is finished and the buffer may be returned to userspace. The driver
  * cannot use this buffer anymore until it is queued back to it by videobuf
  * by the means of buf_queue callback. Only buffers previously queued to the
  * driver by buf_queue can be passed to this function.
+ *
+ * While streaming a buffer can only be returned in state DONE or ERROR.
+ * The start_streaming op can also return them in case the DMA engine cannot
+ * be started for some reason. In that case the buffers should be returned with
+ * state QUEUED.
  */
 void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 {
@@ -1052,11 +1067,17 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 	unsigned long flags;
 	unsigned int plane;
 
-	if (vb->state != VB2_BUF_STATE_ACTIVE)
+	if (WARN_ON(vb->state != VB2_BUF_STATE_ACTIVE))
 		return;
 
-	if (state != VB2_BUF_STATE_DONE && state != VB2_BUF_STATE_ERROR)
-		return;
+	if (!q->start_streaming_called) {
+		if (WARN_ON(state != VB2_BUF_STATE_QUEUED))
+			state = VB2_BUF_STATE_QUEUED;
+	} else if (!WARN_ON(!q->start_streaming_called)) {
+		if (WARN_ON(state != VB2_BUF_STATE_DONE &&
+			    state != VB2_BUF_STATE_ERROR))
+			state = VB2_BUF_STATE_ERROR;
+	}
 
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	/*
@@ -1075,10 +1096,14 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
 	/* Add the buffer to the done buffers list */
 	spin_lock_irqsave(&q->done_lock, flags);
 	vb->state = state;
-	list_add_tail(&vb->done_entry, &q->done_list);
+	if (state != VB2_BUF_STATE_QUEUED)
+		list_add_tail(&vb->done_entry, &q->done_list);
 	atomic_dec(&q->owned_by_drv_count);
 	spin_unlock_irqrestore(&q->done_lock, flags);
 
+	if (state == VB2_BUF_STATE_QUEUED)
+		return;
+
 	/* Inform any processes that may be waiting for buffers */
 	wake_up(&q->done_wq);
 }
@@ -1549,34 +1574,49 @@ EXPORT_SYMBOL_GPL(vb2_prepare_buf);
  * vb2_start_streaming() - Attempt to start streaming.
  * @q:		videobuf2 queue
  *
- * If there are not enough buffers, then retry_start_streaming is set to
- * 1 and 0 is returned. The next time a buffer is queued and
- * retry_start_streaming is 1, this function will be called again to
- * retry starting the DMA engine.
+ * Attempt to start streaming. When this function is called there must be
+ * at least q->min_buffers_needed buffers queued up (i.e. the minimum
+ * number of buffers required for the DMA engine to function). If the
+ * @start_streaming op fails it is supposed to return all the driver-owned
+ * buffers back to vb2 in state QUEUED. Check if that happened and if
+ * not warn and reclaim them forcefully.
  */
 static int vb2_start_streaming(struct vb2_queue *q)
 {
+	struct vb2_buffer *vb;
 	int ret;
 
-	/* Tell the driver to start streaming */
-	ret = call_qop(q, start_streaming, q, atomic_read(&q->owned_by_drv_count));
-	if (ret)
-		fail_qop(q, start_streaming);
-
 	/*
-	 * If there are not enough buffers queued to start streaming, then
-	 * the start_streaming operation will return -ENOBUFS and you have to
-	 * retry when the next buffer is queued.
+	 * If any buffers were queued before streamon,
+	 * we can now pass them to driver for processing.
 	 */
-	if (ret == -ENOBUFS) {
-		dprintk(1, "qbuf: not enough buffers, retry when more buffers are queued.\n");
-		q->retry_start_streaming = 1;
+	list_for_each_entry(vb, &q->queued_list, queued_entry)
+		__enqueue_in_driver(vb);
+
+	/* Tell the driver to start streaming */
+	ret = call_qop(q, start_streaming, q,
+		       atomic_read(&q->owned_by_drv_count));
+	q->start_streaming_called = ret == 0;
+	if (!ret)
 		return 0;
+
+	fail_qop(q, start_streaming);
+	dprintk(1, "qbuf: driver refused to start streaming\n");
+	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
+		unsigned i;
+
+		/*
+		 * Forcefully reclaim buffers if the driver did not
+		 * correctly return them to vb2.
+		 */
+		for (i = 0; i < q->num_buffers; ++i) {
+			vb = q->bufs[i];
+			if (vb->state == VB2_BUF_STATE_ACTIVE)
+				vb2_buffer_done(vb, VB2_BUF_STATE_QUEUED);
+		}
+		/* Must be zero now */
+		WARN_ON(atomic_read(&q->owned_by_drv_count));
 	}
-	if (ret)
-		dprintk(1, "qbuf: driver refused to start streaming\n");
-	else
-		q->retry_start_streaming = 0;
 	return ret;
 }
 
@@ -1612,19 +1652,27 @@ static int vb2_internal_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
 	 * dequeued in dqbuf.
 	 */
 	list_add_tail(&vb->queued_entry, &q->queued_list);
+	q->queued_count++;
 	vb->state = VB2_BUF_STATE_QUEUED;
 
 	/*
 	 * If already streaming, give the buffer to driver for processing.
 	 * If not, the buffer will be given to driver on next streamon.
 	 */
-	if (q->streaming)
+	if (q->start_streaming_called)
 		__enqueue_in_driver(vb);
 
 	/* Fill buffer information for the userspace */
 	__fill_v4l2_buffer(vb, b);
 
-	if (q->retry_start_streaming) {
+	/*
+	 * If streamon has been called, and we haven't yet called
+	 * start_streaming() since not enough buffers were queued, and
+	 * we now have reached the minimum number of queued buffers,
+	 * then we can finally call start_streaming().
+	 */
+	if (q->streaming && !q->start_streaming_called &&
+	    q->queued_count >= q->min_buffers_needed) {
 		ret = vb2_start_streaming(q);
 		if (ret)
 			return ret;
@@ -1779,7 +1827,7 @@ int vb2_wait_for_all_buffers(struct vb2_queue *q)
 		return -EINVAL;
 	}
 
-	if (!q->retry_start_streaming)
+	if (q->start_streaming_called)
 		wait_event(q->done_wq, !atomic_read(&q->owned_by_drv_count));
 	return 0;
 }
@@ -1840,6 +1888,7 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
 	__fill_v4l2_buffer(vb, b);
 	/* Remove from videobuf queue */
 	list_del(&vb->queued_entry);
+	q->queued_count--;
 	/* go back to dequeued state */
 	__vb2_dqbuf(vb);
 
@@ -1890,18 +1939,23 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
 {
 	unsigned int i;
 
-	if (q->retry_start_streaming) {
-		q->retry_start_streaming = 0;
-		q->streaming = 0;
-	}
-
 	/*
 	 * Tell driver to stop all transactions and release all queued
 	 * buffers.
 	 */
-	if (q->streaming)
+	if (q->start_streaming_called)
 		call_qop(q, stop_streaming, q);
 	q->streaming = 0;
+	q->start_streaming_called = 0;
+	q->queued_count = 0;
+
+	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
+		for (i = 0; i < q->num_buffers; ++i)
+			if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
+				vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
+		/* Must be zero now */
+		WARN_ON(atomic_read(&q->owned_by_drv_count));
+	}
 
 	/*
 	 * Remove all buffers from videobuf's list...
@@ -1937,7 +1991,6 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
 
 static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
 {
-	struct vb2_buffer *vb;
 	int ret;
 
 	if (type != q->type) {
@@ -1954,19 +2007,22 @@ static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
 		dprintk(1, "streamon: no buffers have been allocated\n");
 		return -EINVAL;
 	}
+	if (q->num_buffers < q->min_buffers_needed) {
+		dprintk(1, "streamon: need at least %u allocated buffers\n",
+				q->min_buffers_needed);
+		return -EINVAL;
+	}
 
 	/*
-	 * If any buffers were queued before streamon,
-	 * we can now pass them to driver for processing.
+	 * Tell driver to start streaming provided sufficient buffers
+	 * are available.
 	 */
-	list_for_each_entry(vb, &q->queued_list, queued_entry)
-		__enqueue_in_driver(vb);
-
-	/* Tell driver to start streaming. */
-	ret = vb2_start_streaming(q);
-	if (ret) {
-		__vb2_queue_cancel(q);
-		return ret;
+	if (q->queued_count >= q->min_buffers_needed) {
+		ret = vb2_start_streaming(q);
+		if (ret) {
+			__vb2_queue_cancel(q);
+			return ret;
+		}
 	}
 
 	q->streaming = 1;
diff --git a/drivers/staging/media/davinci_vpfe/vpfe_video.c b/drivers/staging/media/davinci_vpfe/vpfe_video.c
index 1f3b0f9..8c101cb 100644
--- a/drivers/staging/media/davinci_vpfe/vpfe_video.c
+++ b/drivers/staging/media/davinci_vpfe/vpfe_video.c
@@ -1201,8 +1201,6 @@ static int vpfe_start_streaming(struct vb2_queue *vq, unsigned int count)
 	unsigned long addr;
 	int ret;
 
-	if (count == 0)
-		return -ENOBUFS;
 	ret = mutex_lock_interruptible(&video->lock);
 	if (ret)
 		goto streamoff;
@@ -1327,6 +1325,7 @@ static int vpfe_reqbufs(struct file *file, void *priv,
 	q->type = req_buf->type;
 	q->io_modes = VB2_MMAP | VB2_USERPTR;
 	q->drv_priv = fh;
+	q->min_buffers_needed = 1;
 	q->ops = &video_qops;
 	q->mem_ops = &vb2_dma_contig_memops;
 	q->buf_struct_size = sizeof(struct vpfe_cap_buffer);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 4f8dce2..8c9ab55 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -354,20 +354,24 @@ struct v4l2_fh;
  * @gfp_flags:	additional gfp flags used when allocating the buffers.
  *		Typically this is 0, but it may be e.g. GFP_DMA or __GFP_DMA32
  *		to force the buffer allocation to a specific memory zone.
+ * @min_buffers_needed: the minimum number of buffers needed before
+ *		start_streaming() can be called. Used when a DMA engine
+ *		cannot be started unless at least this number of buffers
+ *		have been queued into the driver.
  *
  * @memory:	current memory type used
  * @bufs:	videobuf buffer structures
  * @num_buffers: number of allocated/used buffers
  * @queued_list: list of buffers currently queued from userspace
+ * @queued_count: number of buffers queued and ready for streaming.
  * @owned_by_drv_count: number of buffers owned by the driver
  * @done_list:	list of buffers ready to be dequeued to userspace
  * @done_lock:	lock to protect done_list list
  * @done_wq:	waitqueue for processes waiting for buffers ready to be dequeued
  * @alloc_ctx:	memory type/allocator-specific contexts for each plane
  * @streaming:	current streaming state
- * @retry_start_streaming: start_streaming() was called, but there were not enough
- *		buffers queued. If set, then retry calling start_streaming when
- *		queuing a new buffer.
+ * @start_streaming_called: start_streaming() was called successfully and we
+ *		started streaming.
  * @fileio:	file io emulator internal data, used only if emulator is active
  */
 struct vb2_queue {
@@ -383,6 +387,7 @@ struct vb2_queue {
 	unsigned int			buf_struct_size;
 	u32				timestamp_type;
 	gfp_t				gfp_flags;
+	u32				min_buffers_needed;
 
 /* private: internal use only */
 	enum v4l2_memory		memory;
@@ -390,6 +395,7 @@ struct vb2_queue {
 	unsigned int			num_buffers;
 
 	struct list_head		queued_list;
+	unsigned int			queued_count;
 
 	atomic_t			owned_by_drv_count;
 	struct list_head		done_list;
@@ -400,7 +406,7 @@ struct vb2_queue {
 	unsigned int			plane_sizes[VIDEO_MAX_PLANES];
 
 	unsigned int			streaming:1;
-	unsigned int			retry_start_streaming:1;
+	unsigned int			start_streaming_called:1;
 
 	struct vb2_fileio_data		*fileio;
 
-- 
1.9.0

Re: [REVIEWv4 PATCH 12/18] vb2: only call start_streaming if sufficient buffers are queued

[Laurent Pinchart]

Hi Hans,

On Tuesday 04 March 2014 11:42:20 Hans Verkuil wrote:
> From: Hans Verkuil <hans.verkuil@cisco.com>
> 
> In commit 02f142ecd24aaf891324ffba8527284c1731b561 support was added to
> start_streaming to return -ENOBUFS if insufficient buffers were queued
> for the DMA engine to start. The vb2 core would attempt calling
> start_streaming again if another buffer would be queued up.
> 
> Later analysis uncovered problems with the queue management if
> start_streaming would return an error: the buffers are enqueued to the
> driver before the start_streaming op is called, so after an error they are
> never returned to the vb2 core. The solution for this is to let the driver
> return them to the vb2 core in case of an error while starting the DMA
> engine. However, in the case of -ENOBUFS that would be weird: it is not a
> real error, it just says that more buffers are needed. Requiring
> start_streaming to give them back only to have them requeued again the next
> time the application calls QBUF is inefficient.
> 
> This patch changes this mechanism: it adds a 'min_buffers_needed' field
> to vb2_queue that drivers can set with the minimum number of buffers
> required to start the DMA engine. The start_streaming op is only called
> if enough buffers are queued. The -ENOBUFS handling has been dropped in
> favor of this new method.
> 
> Drivers are expected to return buffers back to vb2 core with state QUEUED
> if start_streaming would return an error. The vb2 core checks for this
> and produces a warning if that didn't happen and it will forcefully
> reclaim such buffers to ensure that the internal vb2 core state remains
> consistent and all buffer-related resources have been correctly freed
> and all op calls have been balanced.
> 
> __reqbufs() has been updated to check that at least min_buffers_needed
> buffers could be allocated. If fewer buffers were allocated then __reqbufs
> will free what was allocated and return -ENOMEM. Based on a suggestion from
> Pawel Osciak.
> 
> __create_bufs() doesn't do that check, since the use of __create_bufs
> assumes some advance scenario where the user might want more control.
> Instead streamon will check if enough buffers were allocated to prevent
> streaming with fewer than the minimum required number of buffers.
> 
> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> ---
>  drivers/media/platform/davinci/vpbe_display.c   |   6 +-
>  drivers/media/platform/davinci/vpif_capture.c   |   7 +-
>  drivers/media/platform/davinci/vpif_display.c   |   7 +-
>  drivers/media/platform/s5p-tv/mixer_video.c     |   6 +-
>  drivers/media/v4l2-core/videobuf2-core.c        | 146 ++++++++++++++-------
>  drivers/staging/media/davinci_vpfe/vpfe_video.c |   3 +-
>  include/media/videobuf2-core.h                  |  14 ++-
>  7 files changed, 116 insertions(+), 73 deletions(-)

[snip]

> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
> b/drivers/media/v4l2-core/videobuf2-core.c index 07cce7f..1f6eccf 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c

[snip]

> @@ -1890,18 +1939,23 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>  {
>  	unsigned int i;
> 
> -	if (q->retry_start_streaming) {
> -		q->retry_start_streaming = 0;
> -		q->streaming = 0;
> -	}
> -
>  	/*
>  	 * Tell driver to stop all transactions and release all queued
>  	 * buffers.
>  	 */
> -	if (q->streaming)
> +	if (q->start_streaming_called)
>  		call_qop(q, stop_streaming, q);
>  	q->streaming = 0;
> +	q->start_streaming_called = 0;
> +	q->queued_count = 0;
> +
> +	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {

What's the rationale for a WARN_ON() here ? Wouldn't it simplify drivers to 
handle buffer completion inside vb2 when stopping the stream ?

> +		for (i = 0; i < q->num_buffers; ++i)
> +			if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
> +				vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
> +		/* Must be zero now */
> +		WARN_ON(atomic_read(&q->owned_by_drv_count));
> +	}
> 
>  	/*
>  	 * Remove all buffers from videobuf's list...

-- 
Regards,

Laurent Pinchart

Re: [REVIEWv4 PATCH 12/18] vb2: only call start_streaming if sufficient buffers are queued

[Hans Verkuil]

On 04/21/2014 02:02 AM, Laurent Pinchart wrote:
> Hi Hans,
> 
> On Tuesday 04 March 2014 11:42:20 Hans Verkuil wrote:
>> From: Hans Verkuil <hans.verkuil@cisco.com>
>>
>> In commit 02f142ecd24aaf891324ffba8527284c1731b561 support was added to
>> start_streaming to return -ENOBUFS if insufficient buffers were queued
>> for the DMA engine to start. The vb2 core would attempt calling
>> start_streaming again if another buffer would be queued up.
>>
>> Later analysis uncovered problems with the queue management if
>> start_streaming would return an error: the buffers are enqueued to the
>> driver before the start_streaming op is called, so after an error they are
>> never returned to the vb2 core. The solution for this is to let the driver
>> return them to the vb2 core in case of an error while starting the DMA
>> engine. However, in the case of -ENOBUFS that would be weird: it is not a
>> real error, it just says that more buffers are needed. Requiring
>> start_streaming to give them back only to have them requeued again the next
>> time the application calls QBUF is inefficient.
>>
>> This patch changes this mechanism: it adds a 'min_buffers_needed' field
>> to vb2_queue that drivers can set with the minimum number of buffers
>> required to start the DMA engine. The start_streaming op is only called
>> if enough buffers are queued. The -ENOBUFS handling has been dropped in
>> favor of this new method.
>>
>> Drivers are expected to return buffers back to vb2 core with state QUEUED
>> if start_streaming would return an error. The vb2 core checks for this
>> and produces a warning if that didn't happen and it will forcefully
>> reclaim such buffers to ensure that the internal vb2 core state remains
>> consistent and all buffer-related resources have been correctly freed
>> and all op calls have been balanced.
>>
>> __reqbufs() has been updated to check that at least min_buffers_needed
>> buffers could be allocated. If fewer buffers were allocated then __reqbufs
>> will free what was allocated and return -ENOMEM. Based on a suggestion from
>> Pawel Osciak.
>>
>> __create_bufs() doesn't do that check, since the use of __create_bufs
>> assumes some advance scenario where the user might want more control.
>> Instead streamon will check if enough buffers were allocated to prevent
>> streaming with fewer than the minimum required number of buffers.
>>
>> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
>> ---
>>  drivers/media/platform/davinci/vpbe_display.c   |   6 +-
>>  drivers/media/platform/davinci/vpif_capture.c   |   7 +-
>>  drivers/media/platform/davinci/vpif_display.c   |   7 +-
>>  drivers/media/platform/s5p-tv/mixer_video.c     |   6 +-
>>  drivers/media/v4l2-core/videobuf2-core.c        | 146 ++++++++++++++-------
>>  drivers/staging/media/davinci_vpfe/vpfe_video.c |   3 +-
>>  include/media/videobuf2-core.h                  |  14 ++-
>>  7 files changed, 116 insertions(+), 73 deletions(-)
> 
> [snip]
> 
>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
>> b/drivers/media/v4l2-core/videobuf2-core.c index 07cce7f..1f6eccf 100644
>> --- a/drivers/media/v4l2-core/videobuf2-core.c
>> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> 
> [snip]
> 
>> @@ -1890,18 +1939,23 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>>  {
>>  	unsigned int i;
>>
>> -	if (q->retry_start_streaming) {
>> -		q->retry_start_streaming = 0;
>> -		q->streaming = 0;
>> -	}
>> -
>>  	/*
>>  	 * Tell driver to stop all transactions and release all queued
>>  	 * buffers.
>>  	 */
>> -	if (q->streaming)
>> +	if (q->start_streaming_called)
>>  		call_qop(q, stop_streaming, q);
>>  	q->streaming = 0;
>> +	q->start_streaming_called = 0;
>> +	q->queued_count = 0;
>> +
>> +	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
> 
> What's the rationale for a WARN_ON() here ? Wouldn't it simplify drivers to 
> handle buffer completion inside vb2 when stopping the stream ?

No.

The deal is that vb2 hands the buffer over to the driver via the buf_queue op
and the driver hands it back via the vb2_buffer_done call. In between the driver
owns the buffer. Typically the driver adds the buffer to an internal list in
the buf_queue op and deletes it from that list before calling vb2_buffer_done.

If vb2 cleans up 'dangling' buffers, then that means that that internal list
gets out of sync. That can cause all sorts of nasty problems. It is the reason
why so many drivers struggle with where that internal list should be initialized.

By warning when buf_queue and vb2_buffer_done are no longer balanced this driver
error is now detected properly and the driver can be fixed. By keeping these
calls balanced the buffer list in the driver will always be consistent with the
internal vb2 state.

This error is pretty nasty since it will only show up in corner cases such as
queuing buffers without ever calling STREAMON, or if start_streaming fails,
etc.

These days v4l2-compliance tests for the first corner case (QBUF without STREAMON),
so together with the WARN_ON we have a reasonable detection of this.

Regards,

	Hans

>> +		for (i = 0; i < q->num_buffers; ++i)
>> +			if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
>> +				vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
>> +		/* Must be zero now */
>> +		WARN_ON(atomic_read(&q->owned_by_drv_count));
>> +	}
>>
>>  	/*
>>  	 * Remove all buffers from videobuf's list...
> 

[REVIEWv4 PATCH 13/18] vb2: properly clean up PREPARED and QUEUED buffers

[Hans Verkuil]

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

If __reqbufs was called then existing buffers are freed. However, if that
happens without ever having started STREAMON, but if buffers have been queued,
then the buf_finish op is never called.

Add a call to __vb2_queue_cancel in __reqbufs so that these buffers are
cleaned up there as well.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 1f6eccf..8dc8d50 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -96,6 +96,8 @@ module_param(debug, int, 0644);
 				 V4L2_BUF_FLAG_PREPARED | \
 				 V4L2_BUF_FLAG_TIMESTAMP_MASK)
 
+static void __vb2_queue_cancel(struct vb2_queue *q);
+
 /**
  * __vb2_buf_mem_alloc() - allocate video memory for the given buffer
  */
@@ -789,6 +791,12 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 			return -EBUSY;
 		}
 
+		/*
+		 * Call queue_cancel to clean up any buffers in the PREPARED or
+		 * QUEUED state which is possible if buffers were prepared or
+		 * queued without ever calling STREAMON.
+		 */
+		__vb2_queue_cancel(q);
 		ret = __vb2_queue_free(q, q->num_buffers);
 		if (ret)
 			return ret;
-- 
1.9.0

[REVIEWv4 PATCH 14/18] vb2: replace BUG by WARN_ON

[Hans Verkuil]

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

No need to oops for this, WARN_ON is good enough.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 8dc8d50..e750769 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2538,9 +2538,9 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
 	/*
 	 * Sanity check
 	 */
-	if ((read && !(q->io_modes & VB2_READ)) ||
-	   (!read && !(q->io_modes & VB2_WRITE)))
-		BUG();
+	if (WARN_ON((read && !(q->io_modes & VB2_READ)) ||
+		    (!read && !(q->io_modes & VB2_WRITE))))
+		return -EINVAL;
 
 	/*
 	 * Check if device supports mapping buffers to kernel virtual space.
-- 
1.9.0

[REVIEWv4 PATCH 15/18] vb2: fix streamoff handling if streamon wasn't called.

[Hans Verkuil]

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

If you request buffers, then queue buffers and then call STREAMOFF
those buffers are not returned to their dequeued state because streamoff
will just return if q->streaming was 0.

This means that afterwards you can never QBUF that same buffer again unless
you do STREAMON, REQBUFS or close the filehandle first.

It is clear that if you do STREAMOFF even if no STREAMON was called before,
you still want to have all buffers returned to their proper dequeued state.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index e750769..3c00e22 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2069,14 +2069,14 @@ static int vb2_internal_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
 		return -EINVAL;
 	}
 
-	if (!q->streaming) {
-		dprintk(3, "streamoff successful: not streaming\n");
-		return 0;
-	}
-
 	/*
 	 * Cancel will pause streaming and remove all buffers from the driver
 	 * and videobuf, effectively returning control over them to userspace.
+	 *
+	 * Note that we do this even if q->streaming == 0: if you prepare or
+	 * queue buffers, and then call streamoff without ever having called
+	 * streamon, you would still expect those buffers to be returned to
+	 * their normal dequeued state.
 	 */
 	__vb2_queue_cancel(q);
 
-- 
1.9.0

[REVIEWv4 PATCH 16/18] vb2: call buf_finish after the state check.

[Hans Verkuil]

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

Don't call buf_finish unless we know that the buffer is in a valid state.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 3c00e22..54cea42 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1878,8 +1878,6 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
 	if (ret < 0)
 		return ret;
 
-	call_vb_qop(vb, buf_finish, vb);
-
 	switch (vb->state) {
 	case VB2_BUF_STATE_DONE:
 		dprintk(3, "dqbuf: Returning done buffer\n");
@@ -1892,6 +1890,8 @@ static int vb2_internal_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool n
 		return -EINVAL;
 	}
 
+	call_vb_qop(vb, buf_finish, vb);
+
 	/* Fill buffer information for the userspace */
 	__fill_v4l2_buffer(vb, b);
 	/* Remove from videobuf queue */
-- 
1.9.0

[REVIEWv4 PATCH 17/18] vivi: correctly cleanup after a start_streaming failure

[Hans Verkuil]

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

If start_streaming fails then any queued buffers must be given back
to the vb2 core.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/platform/vivi.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/vivi.c b/drivers/media/platform/vivi.c
index e9cd96e..643937b 100644
--- a/drivers/media/platform/vivi.c
+++ b/drivers/media/platform/vivi.c
@@ -889,10 +889,20 @@ static void buffer_queue(struct vb2_buffer *vb)
 static int start_streaming(struct vb2_queue *vq, unsigned int count)
 {
 	struct vivi_dev *dev = vb2_get_drv_priv(vq);
+	int err;
 
 	dprintk(dev, 1, "%s\n", __func__);
 	dev->seq_count = 0;
-	return vivi_start_generating(dev);
+	err = vivi_start_generating(dev);
+	if (err) {
+		struct vivi_buffer *buf, *tmp;
+
+		list_for_each_entry_safe(buf, tmp, &dev->vidq.active, list) {
+			list_del(&buf->list);
+			vb2_buffer_done(&buf->vb, VB2_BUF_STATE_QUEUED);
+		}
+	}
+	return err;
 }
 
 /* abort streaming and wait for last buffer */
-- 
1.9.0

[REVIEWv4 PATCH 18/18] vivi: fix ENUM_FRAMEINTERVALS implementation

[Hans Verkuil]

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

This function never checked if width and height are correct. Add such
a check so the v4l2-compliance tool returns OK again for vivi.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/platform/vivi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/vivi.c b/drivers/media/platform/vivi.c
index 643937b..7360a84 100644
--- a/drivers/media/platform/vivi.c
+++ b/drivers/media/platform/vivi.c
@@ -1121,7 +1121,11 @@ static int vidioc_enum_frameintervals(struct file *file, void *priv,
 	if (!fmt)
 		return -EINVAL;
 
-	/* regarding width & height - we support any */
+	/* check for valid width/height */
+	if (fival->width < 48 || fival->width > MAX_WIDTH || (fival->width & 3))
+		return -EINVAL;
+	if (fival->height < 32 || fival->height > MAX_HEIGHT)
+		return -EINVAL;
 
 	fival->type = V4L2_FRMIVAL_TYPE_CONTINUOUS;
 
-- 
1.9.0