[media] v4l: vb2-dma-contig: remove reference of alloc_ctx from a buffer

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@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index a05784ffe271..20c95da7aa77 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/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);
         }