drm,i915: Introduce drm_malloc_gfp()

I have instances where I want to use drm_malloc_ab() but with a custom
gfp mask. And with those, where I want a temporary allocation, I want to
try a high-order kmalloc() before using a vmalloc().

So refactor my usage into drm_malloc_gfp().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460113874-17366-6-git-send-email-chris@chris-wilson.co.uk

include/drm/drm_mem_util.h

@@ -54,6 +54,25 @@ static __inline__ void *drm_malloc_ab(size_t nmemb, size_t size)
 			 GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 }
 
+static __inline__ void *drm_malloc_gfp(size_t nmemb, size_t size, gfp_t gfp)
+{
+	if (size != 0 && nmemb > SIZE_MAX / size)
+		return NULL;
+
+	if (size * nmemb <= PAGE_SIZE)
+		return kmalloc(nmemb * size, gfp);
+
+	if (gfp & __GFP_RECLAIMABLE) {
+		void *ptr = kmalloc(nmemb * size,
+				    gfp | __GFP_NOWARN | __GFP_NORETRY);
+		if (ptr)
+			return ptr;
+	}
+
+	return __vmalloc(size * nmemb,
+			 gfp | __GFP_HIGHMEM, PAGE_KERNEL);
+}
+
 static __inline void drm_free_large(void *ptr)
 {
 	kvfree(ptr);