diff mbox series

cgroup/cpuset: no need to explicitly init a global static variable

Message ID 20221220151415.856093-1-neelx@redhat.com
State New
Headers
Series cgroup/cpuset: no need to explicitly init a global static variable |

Commit Message

Daniel Vacek Dec. 20, 2022, 3:14 p.m. UTC 
  cpuset_rwsem is a static variable. It's initialized at build time and so
there's no need for explicit runtime init leaking one percpu int.

Signed-off-by: Daniel Vacek <neelx@redhat.com>
---
 kernel/cgroup/cpuset.c | 2 --
 1 file changed, 2 deletions(-)

Comments

Waiman Long Dec. 20, 2022, 4:59 p.m. UTC | #1 
On 12/20/22 10:14, Daniel Vacek wrote:
> cpuset_rwsem is a static variable. It's initialized at build time and so
> there's no need for explicit runtime init leaking one percpu int.
>
> Signed-off-by: Daniel Vacek <neelx@redhat.com>
> ---
>   kernel/cgroup/cpuset.c | 2 --
>   1 file changed, 2 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index a29c0b13706bb..87fe410361b3d 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -3281,8 +3281,6 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
>   
>   int __init cpuset_init(void)
>   {
> -	BUG_ON(percpu_init_rwsem(&cpuset_rwsem));
> -
>   	BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
>   	BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
>   	BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));

It will be clearer if you mention that DEFINE_STATIC_PERCPU_RWSEM() is 
used to set up cpuset_rwsem at build time. Other than that, the patch 
looks good to me.

Cheers,
Longman
Aaron Tomlin Dec. 20, 2022, 5:32 p.m. UTC | #2 
On Tue 2022-12-20 16:14 +0100, Daniel Vacek wrote:
> cpuset_rwsem is a static variable. It's initialized at build time and so
> there's no need for explicit runtime init leaking one percpu int.
> 
> Signed-off-by: Daniel Vacek <neelx@redhat.com>
> ---
>  kernel/cgroup/cpuset.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index a29c0b13706bb..87fe410361b3d 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -3281,8 +3281,6 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
>  
>  int __init cpuset_init(void)
>  {
> -	BUG_ON(percpu_init_rwsem(&cpuset_rwsem));
> -
>  	BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
>  	BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
>  	BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));
> -- 
> 2.38.1

Good catch.

Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Mukesh Ojha Dec. 21, 2022, 6:19 a.m. UTC | #3 
Hi,

On 12/20/2022 8:44 PM, Daniel Vacek wrote:
> cpuset_rwsem is a static variable. It's initialized at build time and so
> there's no need for explicit runtime init leaking one percpu int.
> 
> Signed-off-by: Daniel Vacek <neelx@redhat.com>
> ---
>   kernel/cgroup/cpuset.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index a29c0b13706bb..87fe410361b3d 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -3281,8 +3281,6 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
>   
>   int __init cpuset_init(void)
>   {
> -	BUG_ON(percpu_init_rwsem(&cpuset_rwsem));
> -
>   	BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
>   	BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
>   	BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));

Acked-by: Mukesh Ojha <quic_mojha@quicinc.com>

-Mukesh
Daniel Vacek Dec. 21, 2022, 8:49 a.m. UTC | #4 
On Tue, Dec 20, 2022 at 5:59 PM Waiman Long <longman@redhat.com> wrote:
>
> On 12/20/22 10:14, Daniel Vacek wrote:
> > cpuset_rwsem is a static variable. It's initialized at build time and so
> > there's no need for explicit runtime init leaking one percpu int.
>
> It will be clearer if you mention that DEFINE_STATIC_PERCPU_RWSEM() is
> used to set up cpuset_rwsem at build time. Other than that, the patch
> looks good to me.

That's true. I only figured later.
Whoever is going to apply it, feel free to amend the message if you like.

--nX

> Cheers,
> Longman
>
Tejun Heo Jan. 4, 2023, 10:21 p.m. UTC | #5 
On Tue, Dec 20, 2022 at 04:14:15PM +0100, Daniel Vacek wrote:
> cpuset_rwsem is a static variable. It's initialized at build time and so
> there's no need for explicit runtime init leaking one percpu int.
> 
> Signed-off-by: Daniel Vacek <neelx@redhat.com>

Applied to cgroup/for-6.2-fixes with the following description:

    cgroup/cpuset: no need to explicitly init a global static variable
    
    cpuset_rwsem is a static variable defined with DEFINE_STATIC_PERCPU_RWSEM().
    It's initialized at build time and so there's no need for explicit runtime
    init leaking one percpu int.
    
    Signed-off-by: Daniel Vacek <neelx@redhat.com>
    Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
    Acked-by: Mukesh Ojha <quic_mojha@quicinc.com>
    Signed-off-by: Tejun Heo <tj@kernel.org>

Thanks.
diff mbox series

Patch

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index a29c0b13706bb..87fe410361b3d 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3281,8 +3281,6 @@  struct cgroup_subsys cpuset_cgrp_subsys = {
 
 int __init cpuset_init(void)
 {
-	BUG_ON(percpu_init_rwsem(&cpuset_rwsem));
-
 	BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL));
 	BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL));
 	BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL));