mm: memcontrol: use struct_size() in kmalloc()
Subsystems (3)
PATCH 1/1 mm: memcontrol: 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;
void *entry[];
};instance = kmalloc(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 = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
This code was detected with the help of Coccinelle.
--- mm/memcontrol.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
mm/memcontrol.c +1 -2
@@ -3626,8 +3626,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, size = thresholds->primary ? thresholds->primary->size +1 :1 ;/* Allocate memory for new array of thresholds */ - new =kmalloc (sizeof (*new) + size *sizeof (struct mem_cgroup_threshold ), -GFP_KERNEL ); + new =kmalloc (struct_size (new, entries, size),GFP_KERNEL );if (!new) { ret = -ENOMEM ; goto unlock;
Signature · 1 line
2.20.1
Cc Andrew (original patch is here http://lkml.kernel.org/r/20190104183726.GA6374@embeddedor)
Quoted 9 lines · Gustavo A. R. Silva
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[]; };
Quoted 6 lines
instance =
kmalloc(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 =
kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
This looks indeed neater
Quoted 3 lines
This code was detected with the help of Coccinelle.
Signed-off-by Gustavo A. R. Silva <[email protected]>
Thanks
Quoted 20 lines
--- mm/memcontrol.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)mm/memcontrol.c +1
-2@@ -3626,8 +3626,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, size = thresholds->primary ? thresholds->primary->size +1 :1 ;/* Allocate memory for new array of thresholds */ - new =kmalloc (sizeof (*new) + size *sizeof (struct mem_cgroup_threshold ), -GFP_KERNEL ); + new =kmalloc (struct_size (new, entries, size),GFP_KERNEL );if (!new) { ret = -ENOMEM ; goto unlock;Signature · 1 line
2.20.1
Signature · 2 lines
Michal Hocko SUSE Labs
Quoted 44 lines · Gustavo A. R. Silva
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 =
kmalloc(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 =
kmalloc(struct_size(instance, entry, count), GFP_KERNEL);This code was detected with the help of Coccinelle.
Signed-off-by Gustavo A. R. Silva <[email protected]>---
mm/memcontrol.c| 3 +--1 file changed, 1 insertion(+), 2 deletions(-)mm/memcontrol.c +1
-2@@ -3626,8 +3626,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg, size = thresholds->primary ? thresholds->primary->size +1 :1 ;/* Allocate memory for new array of thresholds */ - new =kmalloc (sizeof (*new) + size *sizeof (struct mem_cgroup_threshold ), -GFP_KERNEL ); + new =kmalloc (struct_size (new, entries, size),GFP_KERNEL );if (!new) { ret = -ENOMEM ; goto unlock;Signature · 1 line
2.20.1