[PATCH] qxl: Use struct_size() in kzalloc()

[Gustavo A. R. Silva]

One of the more common cases of allocation size calculations is finding the
size of a structure that has a zero-sized array at the end, along with memory
for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now
use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
---
 drivers/gpu/drm/qxl/qxl_display.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_display.c 
b/drivers/gpu/drm/qxl/qxl_display.c
index ce0b9c40fc21..c8642712412e 100644
--- a/drivers/gpu/drm/qxl/qxl_display.c
+++ b/drivers/gpu/drm/qxl/qxl_display.c
@@ -48,8 +48,8 @@ static int qxl_alloc_client_monitors_config(struct qxl_device 
*qdev,
        }
        if (!qdev->client_monitors_config) {
                qdev->client_monitors_config = kzalloc(
-                               sizeof(struct qxl_monitors_config) +
-                               sizeof(struct qxl_head) * count, GFP_KERNEL);
+                               struct_size(qdev->client_monitors_config,
+                               heads, count), GFP_KERNEL);
                if (!qdev->client_monitors_config)
                        return -ENOMEM;
        }
-- 
2.20.1