Re: [PATCH -next 2/3] cgroup/cpuset: remove fetch_xcpus

[Saket Kumar Bhaskar <skb99@linux.ibm.com>]

On Fri, Aug 16, 2024 at 08:27:26AM +0000, Chen Ridong wrote:
> Both fetch_xcpus and user_xcpus functions are used to retrieve the value
> of exclusive_cpus. If exclusive_cpus is not set, cpus_allowed is the
> implicit value used as exclusive in a local partition. I can not imagine
> a scenario where effective_xcpus is not empty when exclusive_cpus is
> empty. Therefore, I suggest removing the fetch_xcpus function.
> 
> Signed-off-by: Chen Ridong <chenridong@huawei.com>
> ---
>  kernel/cgroup/cpuset.c | 13 +++----------
>  1 file changed, 3 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index fdd5346616d3..8be0259065f5 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -771,13 +771,6 @@ static inline bool xcpus_empty(struct cpuset *cs)
>  	       cpumask_empty(cs->exclusive_cpus);
>  }
>  
> -static inline struct cpumask *fetch_xcpus(struct cpuset *cs)
> -{
> -	return !cpumask_empty(cs->exclusive_cpus) ? cs->exclusive_cpus :
> -	       cpumask_empty(cs->effective_xcpus) ? cs->cpus_allowed
> -						  : cs->effective_xcpus;
> -}
> -
>  /*
>   * cpusets_are_exclusive() - check if two cpusets are exclusive
>   *
> @@ -785,8 +778,8 @@ static inline struct cpumask *fetch_xcpus(struct cpuset *cs)
>   */
>  static inline bool cpusets_are_exclusive(struct cpuset *cs1, struct cpuset *cs2)
>  {
> -	struct cpumask *xcpus1 = fetch_xcpus(cs1);
> -	struct cpumask *xcpus2 = fetch_xcpus(cs2);
> +	struct cpumask *xcpus1 = user_xcpus(cs1);
> +	struct cpumask *xcpus2 = user_xcpus(cs2);
>  
>  	if (cpumask_intersects(xcpus1, xcpus2))
>  		return false;
> @@ -2585,7 +2578,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>  		invalidate = true;
>  		rcu_read_lock();
>  		cpuset_for_each_child(cp, css, parent) {
> -			struct cpumask *xcpus = fetch_xcpus(trialcs);
> +			struct cpumask *xcpus = user_xcpus(trialcs);
>  
>  			if (is_partition_valid(cp) &&
>  			    cpumask_intersects(xcpus, cp->effective_xcpus)) {
> -- 
> 2.34.1
> 

Hi,

In update_cpumask too fetch_xcpus is used. You may want to remove it from there too.

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 40ec4abaf440..1b4ee6403de6 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2587,7 +2587,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
                invalidate = true;
                rcu_read_lock();
                cpuset_for_each_child(cp, css, parent) {
-                       struct cpumask *xcpus = fetch_xcpus(trialcs);
+                       struct cpumask *xcpus = user_xcpus(trialcs);

                        if (is_partition_valid(cp) &&
                            cpumask_intersects(xcpus, cp->effective_xcpus)) {


Reviewed-by: Saket Kumar Bhaskar <skb99@linux.ibm.com> 

Thanks,
Saket