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) + count * sizeof(struct boo), 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 gustavo@embeddedor.com --- drivers/gpu/drm/vc4/vc4_perfmon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_perfmon.c b/drivers/gpu/drm/vc4/vc4_perfmon.c index 437e7a27f21d..495150415020 100644 --- a/drivers/gpu/drm/vc4/vc4_perfmon.c +++ b/drivers/gpu/drm/vc4/vc4_perfmon.c @@ -117,7 +117,7 @@ int vc4_perfmon_create_ioctl(struct drm_device *dev, void *data, return -EINVAL; }

- perfmon = kzalloc(sizeof(*perfmon) + (req->ncounters * sizeof(u64)), + perfmon = kzalloc(struct_size(perfmon, counters, req->ncounters), GFP_KERNEL); if (!perfmon) return -ENOMEM;