[v1] sched: Use struct_size() helper in task_numa_group()

[PATCH -next] sched: Use struct_size() helper in task_numa_group()

Posted by Xiu Jianfeng 4 years, 5 months ago

Make use of struct_size() helper instead of an open-coded calculation.
There is no functional change in this patch.

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
---
 kernel/sched/fair.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 095b0aa378df..265e37be0c92 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2437,11 +2437,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
 	int i;
 
 	if (unlikely(!deref_curr_numa_group(p))) {
-		unsigned int size = sizeof(struct numa_group) +
-				    NR_NUMA_HINT_FAULT_STATS *
-				    nr_node_ids * sizeof(unsigned long);
-
-		grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
+		grp = kzalloc(struct_size(grp, faults, NR_NUMA_HINT_FAULT_STATS * nr_node_ids),
+			      GFP_KERNEL | __GFP_NOWARN);
 		if (!grp)
 			return;
 
-- 
2.17.1

Re: [PATCH -next] sched: Use struct_size() helper in task_numa_group()

Posted by Steven Rostedt 4 years, 5 months ago

On Fri, 7 Jan 2022 10:52:12 +0800
Xiu Jianfeng <xiujianfeng@huawei.com> wrote:

> Make use of struct_size() helper instead of an open-coded calculation.
> There is no functional change in this patch.
> 
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
> ---
>  kernel/sched/fair.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 095b0aa378df..265e37be0c92 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2437,11 +2437,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
>  	int i;
>  
>  	if (unlikely(!deref_curr_numa_group(p))) {
> -		unsigned int size = sizeof(struct numa_group) +
> -				    NR_NUMA_HINT_FAULT_STATS *
> -				    nr_node_ids * sizeof(unsigned long);
> -
> -		grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
> +		grp = kzalloc(struct_size(grp, faults, NR_NUMA_HINT_FAULT_STATS * nr_node_ids),
> +			      GFP_KERNEL | __GFP_NOWARN);

I just replied yesterday. Keep the size variable. The above is too much for
a kzalloc().

-- Steve




>  		if (!grp)
>  			return;
>

Re: [PATCH -next] sched: Use struct_size() helper in task_numa_group()

Posted by xiujianfeng 4 years, 5 months ago

在 2022/1/7 22:36, Steven Rostedt 写道:
> On Fri, 7 Jan 2022 10:52:12 +0800
> Xiu Jianfeng <xiujianfeng@huawei.com> wrote:
>
>> Make use of struct_size() helper instead of an open-coded calculation.
>> There is no functional change in this patch.
>>
>> Link: https://github.com/KSPP/linux/issues/160
>> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
>> ---
>>   kernel/sched/fair.c | 7 ++-----
>>   1 file changed, 2 insertions(+), 5 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 095b0aa378df..265e37be0c92 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -2437,11 +2437,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
>>   	int i;
>>   
>>   	if (unlikely(!deref_curr_numa_group(p))) {
>> -		unsigned int size = sizeof(struct numa_group) +
>> -				    NR_NUMA_HINT_FAULT_STATS *
>> -				    nr_node_ids * sizeof(unsigned long);
>> -
>> -		grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
>> +		grp = kzalloc(struct_size(grp, faults, NR_NUMA_HINT_FAULT_STATS * nr_node_ids),
>> +			      GFP_KERNEL | __GFP_NOWARN);
> I just replied yesterday. Keep the size variable. The above is too much for
> a kzalloc().

thanks, I may missed your reply mail, I'll modify and resend this patch.

>
> -- Steve
>
>
>
>
>>   		if (!grp)
>>   			return;
>>   
> .

Re: [PATCH -next] sched: Use struct_size() helper in task_numa_group()

Posted by Peter Zijlstra 4 years, 5 months ago

On Fri, Jan 07, 2022 at 10:52:12AM +0800, Xiu Jianfeng wrote:
> Make use of struct_size() helper instead of an open-coded calculation.
> There is no functional change in this patch.

Why ?!? This makes something that was trivial to read into something
weird.

Re: [PATCH -next] sched: Use struct_size() helper in task_numa_group()

Posted by Steven Rostedt 4 years, 5 months ago

On Mon, 10 Jan 2022 17:06:30 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Fri, Jan 07, 2022 at 10:52:12AM +0800, Xiu Jianfeng wrote:
> > Make use of struct_size() helper instead of an open-coded calculation.
> > There is no functional change in this patch.  
> 
> Why ?!? This makes something that was trivial to read into something
> weird.

Please take his last patch (which only modifies the update to size) and
makes it more robust.

  https://lore.kernel.org/all/20220110012354.144394-1-xiujianfeng@huawei.com/

Which is much easier to read.

We should really replace all open coded struct_size() code.

-- Steve