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Subject[PATCH net-next] libceph, ceph: use struct_size() in kmalloc()
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;
struct boo entry[];
};

instance = kmalloc(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 = kmalloc(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>
---
net/ceph/osdmap.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 98c0ff3d6441..48a31dc9161c 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -495,9 +495,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
/ sizeof(struct crush_rule_step))
goto bad;
#endif
- r = c->rules[i] = kmalloc(sizeof(*r) +
- yes*sizeof(struct crush_rule_step),
- GFP_NOFS);
+ r = kmalloc(struct_size(r, steps, yes), GFP_NOFS);
+ c->rules[i] = r;
if (r == NULL)
goto badmem;
dout(" rule %d is at %p\n", i, r);
--
2.20.1
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