[PATCH] DRM: exynos: return NULL if exynos_pages_to_sg fails

[Subash Patel]

From: Subash Patel <subash.rp at samsung.com>

exynos_pages_to_sg() internally calls sg_kmalloc() which can return
no pages when the system is under high memory crunch. One such instance
is chromeos-install in the chromeos. This patch adds check for the return
value of the function in subject to return NULL on failure.

BUG=chrome-os-partner:9481
TEST=built, ran on snow and tried chromeos-install without a crash

Change-Id: I0abda74beaedae002a17de9962d7a462a2a7c2fb
Signed-off-by: Subash Patel <subash.rp at samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_dmabuf.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
index 97325c1..c908a29 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
@@ -87,6 +87,10 @@ static struct sg_table *
 	npages = buf->size / buf->page_size;
 
 	sgt = exynos_pages_to_sg(buf->pages, npages, buf->page_size);
+	if (!sgt) {
+		DRM_DEBUG_PRIME("exynos_pages_to_sg returned NULL!\n");
+		goto err_unlock;
+	}
 	nents = dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);
 
 	DRM_DEBUG_PRIME("npages = %d buffer size = 0x%lx page_size = 0x%lx\n",
@@ -241,7 +245,7 @@ struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
 
 
 	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
-	if (IS_ERR(sgt)) {
+	if (IS_ERR_OR_NULL(sgt)) {
 		ret = PTR_ERR(sgt);
 		goto err_buf_detach;
 	}
-- 
1.7.9.5