[PATCH v4 3/5] drm/i915/gem: Pull out size validation into a separate function

shmem_sg_alloc_table is a very large and hard to read function,
so reduce the number of operations it is responsible for by
placing "size" validation ind "page_count" assignment n a new
helper.

Signed-off-by: Krzysztof Karas <[email protected]>
---
v4:
 * Changed helper function to validate size and set page_count
  (Janusz);

 drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 30 +++++++++++++++--------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index af195db63038..f35b7efa1fc2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -62,6 +62,23 @@ void shmem_sg_free_table(struct sg_table *st, struct address_space *mapping,
 	sg_free_table(st);
 }
 
+static int set_page_count_from_size(size_t size, unsigned int *page_count,
+			 struct intel_memory_region *mr)
+{
+	if (overflows_type(size / PAGE_SIZE, *page_count))
+		return -E2BIG;
+
+	/*
+	 * If there's no chance of allocating enough pages for the whole
+	 * object, bail early.
+	 */
+	if (size > resource_size(&mr->region))
+		return -ENOMEM;
+
+	*page_count = size / PAGE_SIZE;
+	return 0;
+}
+
 int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 			 size_t size, struct intel_memory_region *mr,
 			 struct address_space *mapping,
@@ -77,16 +94,9 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 	unsigned long i;
 	int ret;
 
-	if (overflows_type(size / PAGE_SIZE, page_count))
-		return -E2BIG;
-
-	page_count = size / PAGE_SIZE;
-	/*
-	 * If there's no chance of allocating enough pages for the whole
-	 * object, bail early.
-	 */
-	if (size > resource_size(&mr->region))
-		return -ENOMEM;
+	ret = set_page_count_from_size(size, &page_count, mr);
+	if (ret < 0)
+		return ret;
 
 	if (sg_alloc_table(st, page_count, GFP_KERNEL | __GFP_NOWARN))
 		return -ENOMEM;
-- 
2.34.1