Re: [PATCH RESEND] sched: Convert paravirt_steal to new static key APIs

[Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>]

Hi Hongyan.

On 8/19/26 1:42 PM, Hongyan Xia wrote:
> From: Hongyan Xia <hongyan.xia@xxxxxxxxxxxxx>
>
> paravirt_steal_rq_enabled and paravirt_steal_enabled use raw static_key
> APIs which are now deprecated. Use the new API instead.
>
> No functional change.
FWIW, looks good to me. One minor nit.

Reviewed-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>

> Signed-off-by: Hongyan Xia <hongyan.xia@xxxxxxxxxxxxx>
> Acked-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> Changed in RESEND:
> - Separate the original series into individual patches. They aren't easy
>    to review as a series.
>
>   arch/arm64/kernel/paravirt.c           | 4 ++--
>   arch/loongarch/kernel/paravirt.c       | 4 ++--
>   arch/powerpc/platforms/pseries/setup.c | 4 ++--
>   arch/riscv/kernel/paravirt.c           | 4 ++--
>   arch/x86/kernel/cpu/vmware.c           | 4 ++--
>   arch/x86/kernel/kvm.c                  | 4 ++--
>   drivers/xen/time.c                     | 4 ++--
>   include/linux/sched/cputime.h          | 6 +++---
>   kernel/sched/core.c                    | 4 ++--
>   kernel/sched/cputime.c                 | 4 ++--
>   10 files changed, 21 insertions(+), 21 deletions(-)
>
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> index 572efb96b23f..30bf61d031eb 100644
> --- a/arch/arm64/kernel/paravirt.c
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -157,9 +157,9 @@ int __init pv_time_init(void)
>   
>   	static_call_update(pv_steal_clock, para_steal_clock);
>   
> -	static_key_slow_inc(&paravirt_steal_enabled);
> +       static_branch_inc(&paravirt_steal_enabled);
>         if (steal_acc)
> -               static_key_slow_inc(&paravirt_steal_rq_enabled);
> +               static_branch_inc(&paravirt_steal_rq_enabled);
>   
>   	pr_info("using stolen time PV\n");
>   
> diff --git a/arch/loongarch/kernel/paravirt.c b/arch/loongarch/kernel/paravirt.c
> index 10821cce554c..e8965a3f8082 100644
> --- a/arch/loongarch/kernel/paravirt.c
> +++ b/arch/loongarch/kernel/paravirt.c
> @@ -308,10 +308,10 @@ int __init pv_time_init(void)
>   
>   	static_call_update(pv_steal_clock, paravt_steal_clock);
>   
> -	static_key_slow_inc(&paravirt_steal_enabled);
> +       static_branch_inc(&paravirt_steal_enabled);
>   #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
>         if (steal_acc)
> -               static_key_slow_inc(&paravirt_steal_rq_enabled);
> +               static_branch_inc(&paravirt_steal_rq_enabled);
>   #endif
>   
>   	if (static_key_enabled(&virt_preempt_key))
> diff --git a/arch/powerpc/platforms/pseries/setup.c 
> b/arch/powerpc/platforms/pseries/setup.c
> index 1223dc961242..8dcbc4bb7025 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -852,9 +852,9 @@ static void __init pSeries_setup_arch(void)
>                         static_branch_enable(&shared_processor);
>                         pv_spinlocks_init();
>   #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
> -                       static_key_slow_inc(&paravirt_steal_enabled);
> +                       static_branch_inc(&paravirt_steal_enabled);
>                         if (steal_acc)
> -                               static_key_slow_inc(&paravirt_steal_rq_enabled);
> +                               static_branch_inc(&paravirt_steal_rq_enabled);
>   #endif
>                 }
>   
> diff --git a/arch/riscv/kernel/paravirt.c b/arch/riscv/kernel/paravirt.c
> index 5f56be79cd06..9c13a6f1ea2a 100644
> --- a/arch/riscv/kernel/paravirt.c
> +++ b/arch/riscv/kernel/paravirt.c
> @@ -116,9 +116,9 @@ int __init pv_time_init(void)
>   
>   	static_call_update(pv_steal_clock, pv_time_steal_clock);
>   
> -	static_key_slow_inc(&paravirt_steal_enabled);
> +       static_branch_inc(&paravirt_steal_enabled);
>         if (steal_acc)
> -               static_key_slow_inc(&paravirt_steal_rq_enabled);
> +               static_branch_inc(&paravirt_steal_rq_enabled);
>   
>   	pr_info("Computing paravirt steal-time\n");
>   
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index 34b73573b108..f7ab9e7902cf 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -328,9 +328,9 @@ static int vmware_cpu_down_prepare(unsigned int cpu)
>   static __init int activate_jump_labels(void)
>   {
>         if (has_steal_clock) {
> -               static_key_slow_inc(&paravirt_steal_enabled);
> +               static_branch_inc(&paravirt_steal_enabled);
>                 if (steal_acc)
> -                       static_key_slow_inc(&paravirt_steal_rq_enabled);
> +                       static_branch_inc(&paravirt_steal_rq_enabled);
>         }
>   
>   	return 0;
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index dcef84da304b..d3dcd64f22c2 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -1052,9 +1052,9 @@ const __initconst struct hypervisor_x86 x86_hyper_kvm = {
>   static __init int activate_jump_labels(void)
>   {
>         if (has_steal_clock) {
> -               static_key_slow_inc(&paravirt_steal_enabled);
> +               static_branch_inc(&paravirt_steal_enabled);
>                 if (steal_acc)
> -                       static_key_slow_inc(&paravirt_steal_rq_enabled);
> +                       static_branch_inc(&paravirt_steal_rq_enabled);
>         }
>   
>   	return 0;
> diff --git a/drivers/xen/time.c b/drivers/xen/time.c
> index a2be0a4d45b0..a02d48a2aa68 100644
> --- a/drivers/xen/time.c
> +++ b/drivers/xen/time.c
> @@ -169,7 +169,7 @@ void __init xen_time_setup_guest(void)
>   
>   	static_call_update(pv_steal_clock, xen_steal_clock);
>   
> -	static_key_slow_inc(&paravirt_steal_enabled);
> +       static_branch_inc(&paravirt_steal_enabled);
>         if (xen_runstate_remote)
> -               static_key_slow_inc(&paravirt_steal_rq_enabled);
> +               static_branch_inc(&paravirt_steal_rq_enabled);
>   }
> diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h
> index e90efaf6d26e..694126411dfe 100644
> --- a/include/linux/sched/cputime.h
> +++ b/include/linux/sched/cputime.h
> @@ -182,9 +182,9 @@ extern unsigned long long
>   task_sched_runtime(struct task_struct *task);
>   
>   #ifdef CONFIG_PARAVIRT
> -struct static_key;
> -extern struct static_key paravirt_steal_enabled;
> -extern struct static_key paravirt_steal_rq_enabled;
> +#include <linux/jump_label.h>
nit:

This looks bit odd to see includes in the middle. I know it is including
only if necessary.
maybe worth an unconditional include in the beginning?

> +DECLARE_STATIC_KEY_FALSE(paravirt_steal_enabled);
> +DECLARE_STATIC_KEY_FALSE(paravirt_steal_rq_enabled);
>   
>   #ifdef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
>   u64 dummy_steal_clock(int cpu);
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 5c07d53e43b5..84d090581a08 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -795,7 +795,7 @@ struct rq *_task_rq_lock(struct task_struct *p, struct 
> rq_flags *rf)
>   
>   /* Use CONFIG_PARAVIRT as this will avoid more #ifdef in arch code. */
>   #ifdef CONFIG_PARAVIRT
> -struct static_key paravirt_steal_rq_enabled;
> +DEFINE_STATIC_KEY_FALSE(paravirt_steal_rq_enabled);
>   #endif
>   
>   static void update_rq_clock_task(struct rq *rq, s64 delta)
> @@ -834,7 +834,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
>         }
>   #endif
>   #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
> -       if (static_key_false((&paravirt_steal_rq_enabled))) {
> +       if (static_branch_unlikely(&paravirt_steal_rq_enabled)) {
>                 u64 prev_steal;
>   
>   		steal = prev_steal = paravirt_steal_clock(cpu_of(rq));
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 06bddaa738e5..f16970ca81d0 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -255,7 +255,7 @@ void __account_forceidle_time(struct task_struct *p, u64 
> delta)
>    * occasion account more time than the calling functions think elapsed.
>    */
>   #ifdef CONFIG_PARAVIRT
> -struct static_key paravirt_steal_enabled;
> +DEFINE_STATIC_KEY_FALSE(paravirt_steal_enabled);
>   
>   #ifdef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
>   static u64 native_steal_clock(int cpu)
> @@ -270,7 +270,7 @@ DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
>   static __always_inline u64 steal_account_process_time(u64 maxtime)
>   {
>   #ifdef CONFIG_PARAVIRT
> -       if (static_key_false(&paravirt_steal_enabled)) {
> +       if (static_branch_unlikely(&paravirt_steal_enabled)) {
>                 u64 steal;
>   
>   		steal = paravirt_steal_clock(smp_processor_id());