V4L/DVB (11840): change kmalloc to vmalloc for sglist allocation in videobuf_dma_map/unmap

Change kmalloc()/kfree() to vmalloc()/vfree() for sglist allocation
during videobuf_dma_map() and videobuf_dma_unmap()

High resolution sensors might require too many contiguous pages
to be allocated for sglist by kmalloc() during videobuf_dma_map()
(i.e. 256Kib for 8MP sensor).
In such situations, kmalloc() could face some problem to find the
required free memory. vmalloc() is a safer solution instead, as the
allocated memory does not need to be contiguous.
Signed-off-by: David Cohen <david.cohen@nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/video4linux/CARDLIST.em28xx

@@ -62,3 +62,5 @@
  64 -> Easy Cap Capture DC-60                   (em2860)
  65 -> IO-DATA GV-MVP/SZ                        (em2820/em2840) [04bb:0515]
  66 -> Empire dual TV                           (em2880)
+ 67 -> Terratec Grabby                          (em2860)        [0ccd:0096]
+ 68 -> Terratec AV350                           (em2860)        [0ccd:0084]

drivers/media/video/videobuf-dma-sg.c

@@ -58,9 +58,10 @@ videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
 	struct page *pg;
 	int i;
 
-	sglist = kcalloc(nr_pages, sizeof(struct scatterlist), GFP_KERNEL);
+	sglist = vmalloc(nr_pages * sizeof(*sglist));
 	if (NULL == sglist)
 		return NULL;
+	memset(sglist, 0, nr_pages * sizeof(*sglist));
 	sg_init_table(sglist, nr_pages);
 	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
 		pg = vmalloc_to_page(virt);
@@ -72,7 +73,7 @@ videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
 	return sglist;
 
  err:
-	kfree(sglist);
+	vfree(sglist);
 	return NULL;
 }
 
@@ -84,7 +85,7 @@ videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
 
 	if (NULL == pages[0])
 		return NULL;
-	sglist = kmalloc(nr_pages * sizeof(*sglist), GFP_KERNEL);
+	sglist = vmalloc(nr_pages * sizeof(*sglist));
 	if (NULL == sglist)
 		return NULL;
 	sg_init_table(sglist, nr_pages);
@@ -104,12 +105,12 @@ videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
 
  nopage:
 	dprintk(2,"sgl: oops - no page\n");
-	kfree(sglist);
+	vfree(sglist);
 	return NULL;
 
  highmem:
 	dprintk(2,"sgl: oops - highmem page\n");
-	kfree(sglist);
+	vfree(sglist);
 	return NULL;
 }
 
@@ -230,7 +231,7 @@ int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
 						(dma->vmalloc,dma->nr_pages);
 	}
 	if (dma->bus_addr) {
-		dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
+		dma->sglist = vmalloc(sizeof(*dma->sglist));
 		if (NULL != dma->sglist) {
 			dma->sglen  = 1;
 			sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
@@ -248,7 +249,7 @@ int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
 		if (0 == dma->sglen) {
 			printk(KERN_WARNING
 			       "%s: videobuf_map_sg failed\n",__func__);
-			kfree(dma->sglist);
+			vfree(dma->sglist);
 			dma->sglist = NULL;
 			dma->sglen = 0;
 			return -EIO;
@@ -274,7 +275,7 @@ int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
 
 	dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 
-	kfree(dma->sglist);
+	vfree(dma->sglist);
 	dma->sglist = NULL;
 	dma->sglen = 0;
 	return 0;