[media] ivtv: Convert to get_user_pages_unlocked()

Convert ivtv_yuv_prep_user_dma() to use get_user_pages_unlocked() so
that we don't unnecessarily leak knowledge about mm locking into drivers
code.

CC: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/pci/ivtv/ivtv-yuv.c

@@ -75,15 +75,15 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
 	ivtv_udma_get_page_info (&uv_dma, (unsigned long)args->uv_source, 360 * uv_decode_height);
 
 	/* Get user pages for DMA Xfer */
-	down_read(&current->mm->mmap_sem);
-	y_pages = get_user_pages(current, current->mm, y_dma.uaddr, y_dma.page_count, 0, 1, &dma->map[0], NULL);
+	y_pages = get_user_pages_unlocked(current, current->mm,
+				y_dma.uaddr, y_dma.page_count, 0, 1,
+				&dma->map[0]);
 	uv_pages = 0; /* silence gcc. value is set and consumed only if: */
 	if (y_pages == y_dma.page_count) {
-		uv_pages = get_user_pages(current, current->mm,
-					  uv_dma.uaddr, uv_dma.page_count, 0, 1,
-					  &dma->map[y_pages], NULL);
+		uv_pages = get_user_pages_unlocked(current, current->mm,
+					uv_dma.uaddr, uv_dma.page_count, 0, 1,
+					&dma->map[y_pages]);
 	}
-	up_read(&current->mm->mmap_sem);
 
 	if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {
 		int rc = -EFAULT;