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 mirror_set {
...
struct mirror mirror[0];
};
size = sizeof(struct mirror_set) + count * sizeof(struct mirror);
instance = kzalloc(size, 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, mirror, count), GFP_KERNEL)
Notice that, in this case, variable len is not necessary, hence it
is removed.
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
drivers/md/dm-raid1.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 5a51151f680d..f7226ab57fc8 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -878,12 +878,9 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
struct dm_target *ti,
struct dm_dirty_log *dl)
{
- size_t len;
struct mirror_set *ms = NULL;
- len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
-
- ms = kzalloc(len, GFP_KERNEL);
+ ms = kzalloc(struct_size(ms, mirror, nr_mirrors), GFP_KERNEL);
if (!ms) {
ti->error = "Cannot allocate mirror context";
return NULL;
--
2.22.0
--
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