[PATCHv8 06/26] v4l: vb2-dma-contig: remove reference of alloc_ctx from a buffer

[Tomasz Stanislawski]

This patch removes a reference to alloc_ctx from an instance of a DMA
contiguous buffer. It helps to avoid a risk of a dangling pointer if the
context is released while the buffer is still valid. Moreover it removes one
dereference step while accessing a device structure.

Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
---
 drivers/media/video/videobuf2-dma-contig.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c
index a05784f..20c95da 100644
--- a/drivers/media/video/videobuf2-dma-contig.c
+++ b/drivers/media/video/videobuf2-dma-contig.c
@@ -23,7 +23,7 @@ struct vb2_dc_conf {
 };
 
 struct vb2_dc_buf {
-	struct vb2_dc_conf		*conf;
+	struct device			*dev;
 	void				*vaddr;
 	dma_addr_t			dma_addr;
 	unsigned long			size;
@@ -37,22 +37,21 @@ static void vb2_dc_put(void *buf_priv);
 static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
 {
 	struct vb2_dc_conf *conf = alloc_ctx;
+	struct device *dev = conf->dev;
 	struct vb2_dc_buf *buf;
 
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
 		return ERR_PTR(-ENOMEM);
 
-	buf->vaddr = dma_alloc_coherent(conf->dev, size, &buf->dma_addr,
-					GFP_KERNEL);
+	buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr, GFP_KERNEL);
 	if (!buf->vaddr) {
-		dev_err(conf->dev, "dma_alloc_coherent of size %ld failed\n",
-			size);
+		dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 		kfree(buf);
 		return ERR_PTR(-ENOMEM);
 	}
 
-	buf->conf = conf;
+	buf->dev = dev;
 	buf->size = size;
 
 	buf->handler.refcount = &buf->refcount;
@@ -69,7 +68,7 @@ static void vb2_dc_put(void *buf_priv)
 	struct vb2_dc_buf *buf = buf_priv;
 
 	if (atomic_dec_and_test(&buf->refcount)) {
-		dma_free_coherent(buf->conf->dev, buf->size, buf->vaddr,
+		dma_free_coherent(buf->dev, buf->size, buf->vaddr,
 				  buf->dma_addr);
 		kfree(buf);
 	}
-- 
1.7.9.5