| Message ID | 20190829190605.GA17425@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | percpu: Use struct_size() helper | expand |
On Thu, Aug 29, 2019 at 02:06:05PM -0500, 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 pcpu_alloc_info { > ... > struct pcpu_group_info groups[]; > }; > > Make use of the struct_size() helper instead of an open-coded version > in order to avoid any potential type mistakes. > > So, replace the following form: > > sizeof(*ai) + nr_groups * sizeof(ai->groups[0]) > > with: > > struct_size(ai, groups, nr_groups) > > This code was detected with the help of Coccinelle. > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > mm/percpu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/percpu.c b/mm/percpu.c > index 7e2aa0305c27..7e06a1e58720 100644 > --- a/mm/percpu.c > +++ b/mm/percpu.c > @@ -2125,7 +2125,7 @@ struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups, > void *ptr; > int unit; > > - base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]), > + base_size = ALIGN(struct_size(ai, groups, nr_groups), > __alignof__(ai->groups[0].cpu_map[0])); > ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]); > > -- > 2.23.0 > > Hi Gustavo, Sorry about the delay, I meant to get to this before the holiday. I've applied it to for-5.4. Thanks, Dennis
diff --git a/mm/percpu.c b/mm/percpu.c index 7e2aa0305c27..7e06a1e58720 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -2125,7 +2125,7 @@ struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups, void *ptr; int unit; - base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]), + base_size = ALIGN(struct_size(ai, groups, nr_groups), __alignof__(ai->groups[0].cpu_map[0])); ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
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 pcpu_alloc_info { ... struct pcpu_group_info groups[]; }; Make use of the struct_size() helper instead of an open-coded version in order to avoid any potential type mistakes. So, replace the following form: sizeof(*ai) + nr_groups * sizeof(ai->groups[0]) with: struct_size(ai, groups, nr_groups) This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- mm/percpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)