[PATCH 0/5] sched/vtime: vtime.h headers cleanup

[PATCH 0/5] sched/vtime: vtime.h headers cleanup

[Alexander Gordeev]

Hi all,

Please find a small cleanup to vtime_task_switch() wiring.
I split it into smaller patches to allow separate PowerPC
vs s390 reviews. Otherwise patches 2+3 and 4+5 could have
been merged.

I tested it on s390 and compile-tested it on 32- and 64-bit
PowerPC and few other major architectures only, but it is
only of concern for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE-capable
ones (AFAICT).

Thanks!

Alexander Gordeev (5):
  sched/vtime: remove confusing arch_vtime_task_switch() declaration
  sched/vtime: get rid of generic vtime_task_switch() implementation
  s390/vtime: remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover
  s390/irq,nmi: do not include <linux/vtime.h> header
  sched/vtime: do not include <asm/vtime.h> header

 arch/powerpc/include/asm/cputime.h | 13 -------------
 arch/powerpc/kernel/time.c         | 22 ++++++++++++++++++++++
 arch/s390/include/asm/vtime.h      |  2 --
 arch/s390/kernel/irq.c             |  1 +
 arch/s390/kernel/nmi.c             |  1 +
 include/asm-generic/vtime.h        |  1 -
 include/linux/vtime.h              |  5 -----
 kernel/sched/cputime.c             | 13 -------------
 8 files changed, 24 insertions(+), 34 deletions(-)
 delete mode 100644 include/asm-generic/vtime.h

-- 
2.40.1

[PATCH 1/5] sched/vtime: remove confusing arch_vtime_task_switch() declaration

[Alexander Gordeev]

Callback arch_vtime_task_switch() is only defined when
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is selected. Yet, the
function prototype forward declaration is present for
CONFIG_VIRT_CPU_ACCOUNTING_GEN variant. Remove it.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 include/linux/vtime.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 3684487d01e1..593466ceebed 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -18,7 +18,6 @@ extern void vtime_account_idle(struct task_struct *tsk);
 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-extern void arch_vtime_task_switch(struct task_struct *tsk);
 extern void vtime_user_enter(struct task_struct *tsk);
 extern void vtime_user_exit(struct task_struct *tsk);
 extern void vtime_guest_enter(struct task_struct *tsk);
-- 
2.40.1

Re: [PATCH 1/5] sched/vtime: remove confusing arch_vtime_task_switch() declaration

[Frederic Weisbecker]

Le Sun, Jan 28, 2024 at 08:58:50PM +0100, Alexander Gordeev a écrit :
> Callback arch_vtime_task_switch() is only defined when
> CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is selected. Yet, the
> function prototype forward declaration is present for
> CONFIG_VIRT_CPU_ACCOUNTING_GEN variant. Remove it.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

[PATCH 2/5] sched/vtime: get rid of generic vtime_task_switch() implementation

[Alexander Gordeev]

The generic vtime_task_switch() implementation gets built only
if __ARCH_HAS_VTIME_TASK_SWITCH is not defined, but requires an
architecture to implement arch_vtime_task_switch() callback at
the same time, which is confusing.

Further, arch_vtime_task_switch() is implemented for 32-bit PowerPC
architecture only and vtime_task_switch() generic variant is rather
superfluous.

Simplify the whole vtime_task_switch() wiring by moving the existing
generic implementation to PowerPC.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 arch/powerpc/include/asm/cputime.h | 13 -------------
 arch/powerpc/kernel/time.c         | 22 ++++++++++++++++++++++
 kernel/sched/cputime.c             | 13 -------------
 3 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 4961fb38e438..aff858ca99c0 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -32,23 +32,10 @@
 #ifdef CONFIG_PPC64
 #define get_accounting(tsk)	(&get_paca()->accounting)
 #define raw_get_accounting(tsk)	(&local_paca->accounting)
-static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
 
 #else
 #define get_accounting(tsk)	(&task_thread_info(tsk)->accounting)
 #define raw_get_accounting(tsk)	get_accounting(tsk)
-/*
- * Called from the context switch with interrupts disabled, to charge all
- * accumulated times to the current process, and to prepare accounting on
- * the next process.
- */
-static inline void arch_vtime_task_switch(struct task_struct *prev)
-{
-	struct cpu_accounting_data *acct = get_accounting(current);
-	struct cpu_accounting_data *acct0 = get_accounting(prev);
-
-	acct->starttime = acct0->starttime;
-}
 #endif
 
 /*
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index df20cf201f74..c0fdc6d94fee 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -354,6 +354,28 @@ void vtime_flush(struct task_struct *tsk)
 	acct->hardirq_time = 0;
 	acct->softirq_time = 0;
 }
+
+/*
+ * Called from the context switch with interrupts disabled, to charge all
+ * accumulated times to the current process, and to prepare accounting on
+ * the next process.
+ */
+void vtime_task_switch(struct task_struct *prev)
+{
+	if (is_idle_task(prev))
+		vtime_account_idle(prev);
+	else
+		vtime_account_kernel(prev);
+
+	vtime_flush(prev);
+
+	if (!IS_ENABLED(CONFIG_PPC64)) {
+		struct cpu_accounting_data *acct = get_accounting(current);
+		struct cpu_accounting_data *acct0 = get_accounting(prev);
+
+		acct->starttime = acct0->starttime;
+	}
+}
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
 void __no_kcsan __delay(unsigned long loops)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index af7952f12e6c..aa48b2ec879d 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -424,19 +424,6 @@ static inline void irqtime_account_process_tick(struct task_struct *p, int user_
  */
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 
-# ifndef __ARCH_HAS_VTIME_TASK_SWITCH
-void vtime_task_switch(struct task_struct *prev)
-{
-	if (is_idle_task(prev))
-		vtime_account_idle(prev);
-	else
-		vtime_account_kernel(prev);
-
-	vtime_flush(prev);
-	arch_vtime_task_switch(prev);
-}
-# endif
-
 void vtime_account_irq(struct task_struct *tsk, unsigned int offset)
 {
 	unsigned int pc = irq_count() - offset;
-- 
2.40.1

Re: [PATCH 2/5] sched/vtime: get rid of generic vtime_task_switch() implementation

[Frederic Weisbecker]

Le Sun, Jan 28, 2024 at 08:58:51PM +0100, Alexander Gordeev a écrit :
> The generic vtime_task_switch() implementation gets built only
> if __ARCH_HAS_VTIME_TASK_SWITCH is not defined, but requires an
> architecture to implement arch_vtime_task_switch() callback at
> the same time, which is confusing.
> 
> Further, arch_vtime_task_switch() is implemented for 32-bit PowerPC
> architecture only and vtime_task_switch() generic variant is rather
> superfluous.
> 
> Simplify the whole vtime_task_switch() wiring by moving the existing
> generic implementation to PowerPC.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

[PATCH 3/5] s390/vtime: remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover

[Alexander Gordeev]

__ARCH_HAS_VTIME_TASK_SWITCH macro is not used anymore.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 arch/s390/include/asm/vtime.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/s390/include/asm/vtime.h b/arch/s390/include/asm/vtime.h
index fe17e448c0c5..561c91c1a87c 100644
--- a/arch/s390/include/asm/vtime.h
+++ b/arch/s390/include/asm/vtime.h
@@ -2,8 +2,6 @@
 #ifndef _S390_VTIME_H
 #define _S390_VTIME_H
 
-#define __ARCH_HAS_VTIME_TASK_SWITCH
-
 static inline void update_timer_sys(void)
 {
 	S390_lowcore.system_timer += S390_lowcore.last_update_timer - S390_lowcore.exit_timer;
-- 
2.40.1

Re: [PATCH 3/5] s390/vtime: remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover

[Heiko Carstens]

On Sun, Jan 28, 2024 at 08:58:52PM +0100, Alexander Gordeev wrote:
> __ARCH_HAS_VTIME_TASK_SWITCH macro is not used anymore.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
> ---
>  arch/s390/include/asm/vtime.h | 2 --
>  1 file changed, 2 deletions(-)

Acked-by: Heiko Carstens <hca@linux.ibm.com>

Re: [PATCH 3/5] s390/vtime: remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover

[Frederic Weisbecker]

Le Sun, Jan 28, 2024 at 08:58:52PM +0100, Alexander Gordeev a écrit :
> __ARCH_HAS_VTIME_TASK_SWITCH macro is not used anymore.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>


> ---
>  arch/s390/include/asm/vtime.h | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/s390/include/asm/vtime.h b/arch/s390/include/asm/vtime.h
> index fe17e448c0c5..561c91c1a87c 100644
> --- a/arch/s390/include/asm/vtime.h
> +++ b/arch/s390/include/asm/vtime.h
> @@ -2,8 +2,6 @@
>  #ifndef _S390_VTIME_H
>  #define _S390_VTIME_H
>  
> -#define __ARCH_HAS_VTIME_TASK_SWITCH
> -
>  static inline void update_timer_sys(void)
>  {
>  	S390_lowcore.system_timer += S390_lowcore.last_update_timer - S390_lowcore.exit_timer;
> -- 
> 2.40.1
> 

[PATCH 4/5] s390/irq,nmi: do not include <linux/vtime.h> header

[Alexander Gordeev]

update_timer_sys() and update_timer_mcck() are inlines used for
CPU time accounting from the interrupt and machine-check handlers.
These routines are specific to s390 architecture, but declared
via <linux/vtime.h> header, which in turn inludes <asm/vtime.h>.
Avoid the extra loop and include <asm/vtime.h> header directly.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 arch/s390/kernel/irq.c | 1 +
 arch/s390/kernel/nmi.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 6f71b0ce1068..259496fe0ef9 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -29,6 +29,7 @@
 #include <asm/hw_irq.h>
 #include <asm/stacktrace.h>
 #include <asm/softirq_stack.h>
+#include <asm/vtime.h>
 #include "entry.h"
 
 DEFINE_PER_CPU_SHARED_ALIGNED(struct irq_stat, irq_stat);
diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 9ad44c26d1a2..4422a27faace 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -32,6 +32,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/pai.h>
 #include <asm/vx-insn.h>
+#include <asm/vtime.h>
 #include <asm/fpu/api.h>
 
 struct mcck_struct {
-- 
2.40.1

Re: [PATCH 4/5] s390/irq,nmi: do not include <linux/vtime.h> header

[Heiko Carstens]

On Sun, Jan 28, 2024 at 08:58:53PM +0100, Alexander Gordeev wrote:
> update_timer_sys() and update_timer_mcck() are inlines used for
> CPU time accounting from the interrupt and machine-check handlers.
> These routines are specific to s390 architecture, but declared
> via <linux/vtime.h> header, which in turn inludes <asm/vtime.h>.
> Avoid the extra loop and include <asm/vtime.h> header directly.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
> ---
>  arch/s390/kernel/irq.c | 1 +
>  arch/s390/kernel/nmi.c | 1 +
>  2 files changed, 2 insertions(+)
...
> +++ b/arch/s390/kernel/irq.c
> +#include <asm/vtime.h>
...
> +++ b/arch/s390/kernel/nmi.c
> +#include <asm/vtime.h>

It is confusing when the patch subject is "do not include.." and all
what this patch is doing is to add two includes. I see what this is
doing: getting rid of the implicit include of asm/vtime.h most likely
via linux/hardirq.h, but that's not very obvious.

Anyway:
Acked-by: Heiko Carstens <hca@linux.ibm.com>

Re: [PATCH 4/5] s390/irq,nmi: do not include <linux/vtime.h> header

[Alexander Gordeev]

On Mon, Jan 29, 2024 at 10:51:44AM +0100, Heiko Carstens wrote:
> It is confusing when the patch subject is "do not include.." and all
> what this patch is doing is to add two includes. I see what this is
> doing: getting rid of the implicit include of asm/vtime.h most likely
> via linux/hardirq.h, but that's not very obvious.
> 
> Anyway:
> Acked-by: Heiko Carstens <hca@linux.ibm.com>

Thank you, Heiko!

Whether this wording sounds better?

s390/irq,nmi: include <asm/vtime.h> header directly                         

update_timer_sys() and update_timer_mcck() are inlines used for             
CPU time accounting from the interrupt and machine-check handlers.          
These routines are specific to s390 architecture, but included              
via <linux/vtime.h> header implicitly. Avoid the extra loop and             
include <asm/vtime.h> header directly.                                      

[PATCH 5/5] sched/vtime: do not include <asm/vtime.h> header

[Alexander Gordeev]

There is no architecture-specific code or data left
that generic <linux/vtime.h> needs to know about.
Thus, avoid the inclusion of <asm/vtime.h> header.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 include/asm-generic/vtime.h | 1 -
 include/linux/vtime.h       | 4 ----
 2 files changed, 5 deletions(-)
 delete mode 100644 include/asm-generic/vtime.h

diff --git a/include/asm-generic/vtime.h b/include/asm-generic/vtime.h
deleted file mode 100644
index b1a49677fe25..000000000000
--- a/include/asm-generic/vtime.h
+++ /dev/null
@@ -1 +0,0 @@
-/* no content, but patch(1) dislikes empty files */
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 593466ceebed..29dd5b91dd7d 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -5,10 +5,6 @@
 #include <linux/context_tracking_state.h>
 #include <linux/sched.h>
 
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-#include <asm/vtime.h>
-#endif
-
 /*
  * Common vtime APIs
  */
-- 
2.40.1

Re: [PATCH 5/5] sched/vtime: do not include <asm/vtime.h> header

[Heiko Carstens]

On Sun, Jan 28, 2024 at 08:58:54PM +0100, Alexander Gordeev wrote:
> There is no architecture-specific code or data left
> that generic <linux/vtime.h> needs to know about.
> Thus, avoid the inclusion of <asm/vtime.h> header.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
> ---
>  include/asm-generic/vtime.h | 1 -
>  include/linux/vtime.h       | 4 ----
>  2 files changed, 5 deletions(-)
>  delete mode 100644 include/asm-generic/vtime.h

I guess you need to get rid of this as well:

arch/powerpc/include/asm/Kbuild:generic-y += vtime.h

Re: [PATCH 5/5] sched/vtime: do not include <asm/vtime.h> header

[Frederic Weisbecker]

Le Sun, Jan 28, 2024 at 08:58:54PM +0100, Alexander Gordeev a écrit :
> There is no architecture-specific code or data left
> that generic <linux/vtime.h> needs to know about.
> Thus, avoid the inclusion of <asm/vtime.h> header.
> 
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

Re: [PATCH 5/5] sched/vtime: do not include <asm/vtime.h> header

[Alexander Gordeev]

On Wed, Feb 07, 2024 at 12:30:08AM +0100, Frederic Weisbecker wrote:
> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

Thank you for the review, Frederic!

The Heiko comment is valid and I would add this chunk in v2:

--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -6,5 +6,4 @@ generic-y += agp.h
 generic-y += kvm_types.h
 generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
-generic-y += vtime.h
 generic-y += early_ioremap.h

Would you keep your Reviewed-by?

Re: [PATCH 5/5] sched/vtime: do not include <asm/vtime.h> header

[Frederic Weisbecker]

Le Wed, Feb 07, 2024 at 03:12:57PM +0100, Alexander Gordeev a écrit :
> On Wed, Feb 07, 2024 at 12:30:08AM +0100, Frederic Weisbecker wrote:
> > Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
> 
> Thank you for the review, Frederic!
> 
> The Heiko comment is valid and I would add this chunk in v2:
> 
> --- a/arch/powerpc/include/asm/Kbuild
> +++ b/arch/powerpc/include/asm/Kbuild
> @@ -6,5 +6,4 @@ generic-y += agp.h
>  generic-y += kvm_types.h
>  generic-y += mcs_spinlock.h
>  generic-y += qrwlock.h
> -generic-y += vtime.h
>  generic-y += early_ioremap.h
> 
> Would you keep your Reviewed-by?

Sure!