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dm raid1: use struct_size() with kzalloc()

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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@embeddedor.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Gustavo A. R. Silva 2019-08-05 19:18:25 -05:00 committed by Mike Snitzer
parent 5229b4896e
commit bcd676542c
1 changed files with 2 additions and 5 deletions
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7
drivers/md/dm-raid1.c
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@ -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;
struct mirror_set *ms =
kzalloc(struct_size(ms, mirror, nr_mirrors), GFP_KERNEL);
len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
ms = kzalloc(len, GFP_KERNEL);
if (!ms) {
ti->error = "Cannot allocate mirror context";
return NULL;