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 = devm_kzalloc(dev, 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 = devm_kzalloc(dev, 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>
---
Changes in v2:
 - Fix devm_kzalloc parameter reported by kbuild test robot.

 arch/arm/mach-integrator/impd1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-integrator/impd1.c b/arch/arm/mach-integrator/impd1.c
index eb0149561be2..a0a1e2acdb5e 100644
--- a/arch/arm/mach-integrator/impd1.c
+++ b/arch/arm/mach-integrator/impd1.c
@@ -390,7 +390,7 @@ static int __ref impd1_probe(struct lm_device *dev)
                        char *mmciname;
 
                        lookup = devm_kzalloc(&dev->dev,
-                                             sizeof(*lookup) + 3 * 
sizeof(struct gpiod_lookup),
+                                             struct_size(lookup, table, 3),
                                              GFP_KERNEL);
                        if (!lookup)
                                return -ENOMEM;
-- 
2.20.1

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