| Message ID | 20190104183726.GA6374@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: memcontrol: use struct_size() in kmalloc() | expand |
Cc Andrew (original patch is here http://lkml.kernel.org/r/20190104183726.GA6374@embeddedor) On Fri 04-01-19 12:37:26, Gustavo A. R. Silva wrote: > 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 looks indeed neater > This code was detected with the help of Coccinelle. > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Acked-by: Michal Hocko <mhocko@suse.com> Thanks > --- > mm/memcontrol.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index af7f18b32389..ad256cf7da47 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -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; > -- > 2.20.1
> On Jan 4, 2019, at 11:37 AM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote: > > 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 <gustavo@embeddedor.com> > --- > mm/memcontrol.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index af7f18b32389..ad256cf7da47 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -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; > -- > 2.20.1 > Reviewed-by: William Kucharski <william.kucharski@oracle.com>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index af7f18b32389..ad256cf7da47 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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;
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 <gustavo@embeddedor.com> --- mm/memcontrol.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)