diff mbox series

[RFC,1/3] arm64: entry: Remove unneeded need_resched() loop

Message ID 20190131182339.9835-2-valentin.schneider@arm.com (mailing list archive)
State RFC, archived
Headers show
Series arm/arm64: entry: Remove need_resched() loop | expand

Commit Message

Valentin Schneider Jan. 31, 2019, 6:23 p.m. UTC
Since the enabling and disabling of IRQs within preempt_schedule_irq()
is contained in a need_resched() loop, we don't need the outer arch
code loop.

Reported-by: Julien Thierry <julien.thierry@arm.com>
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Julien Grall <julien.grall@arm.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/kernel/entry.S | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

Comments

Julien Thierry Feb. 1, 2019, 8:46 a.m. UTC | #1
Hi Valentin,

On 31/01/2019 18:23, Valentin Schneider wrote:
> Since the enabling and disabling of IRQs within preempt_schedule_irq()
> is contained in a need_resched() loop, we don't need the outer arch
> code loop.
> 
> Reported-by: Julien Thierry <julien.thierry@arm.com>
> Reported-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Julien Grall <julien.grall@arm.com>
> Cc: Julien Thierry <julien.thierry@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-arm-kernel@lists.infradead.org

Reviewed-by: Julien Thierry <julien.thierry@arm.com>

> ---
>  arch/arm64/kernel/entry.S | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 0ec0c46b2c0c..4d0c81f29a60 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -611,7 +611,7 @@ el1_irq:
>  #ifdef CONFIG_PREEMPT
>  	ldr	x24, [tsk, #TSK_TI_PREEMPT]	// get preempt count
>  	cbnz	x24, 1f				// preempt count != 0
> -	bl	el1_preempt
> +	bl	preempt_schedule_irq		// irq en/disable is done inside
>  1:
>  #endif
>  #ifdef CONFIG_TRACE_IRQFLAGS
> @@ -620,15 +620,6 @@ el1_irq:
>  	kernel_exit 1
>  ENDPROC(el1_irq)
>  
> -#ifdef CONFIG_PREEMPT
> -el1_preempt:
> -	mov	x24, lr
> -1:	bl	preempt_schedule_irq		// irq en/disable is done inside
> -	ldr	x0, [tsk, #TSK_TI_FLAGS]	// get new tasks TI_FLAGS
> -	tbnz	x0, #TIF_NEED_RESCHED, 1b	// needs rescheduling?
> -	ret	x24
> -#endif
> -
>  /*
>   * EL0 mode handlers.
>   */
>
Will Deacon Feb. 1, 2019, 10:21 a.m. UTC | #2
On Thu, Jan 31, 2019 at 06:23:37PM +0000, Valentin Schneider wrote:
> Since the enabling and disabling of IRQs within preempt_schedule_irq()
> is contained in a need_resched() loop, we don't need the outer arch
> code loop.
> 
> Reported-by: Julien Thierry <julien.thierry@arm.com>
> Reported-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Julien Grall <julien.grall@arm.com>
> Cc: Julien Thierry <julien.thierry@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-arm-kernel@lists.infradead.org
> ---
>  arch/arm64/kernel/entry.S | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 0ec0c46b2c0c..4d0c81f29a60 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -611,7 +611,7 @@ el1_irq:
>  #ifdef CONFIG_PREEMPT
>  	ldr	x24, [tsk, #TSK_TI_PREEMPT]	// get preempt count
>  	cbnz	x24, 1f				// preempt count != 0
> -	bl	el1_preempt
> +	bl	preempt_schedule_irq		// irq en/disable is done inside
>  1:
>  #endif
>  #ifdef CONFIG_TRACE_IRQFLAGS
> @@ -620,15 +620,6 @@ el1_irq:
>  	kernel_exit 1
>  ENDPROC(el1_irq)
>  
> -#ifdef CONFIG_PREEMPT
> -el1_preempt:
> -	mov	x24, lr
> -1:	bl	preempt_schedule_irq		// irq en/disable is done inside
> -	ldr	x0, [tsk, #TSK_TI_FLAGS]	// get new tasks TI_FLAGS
> -	tbnz	x0, #TIF_NEED_RESCHED, 1b	// needs rescheduling?
> -	ret	x24
> -#endif
> -

Acked-by: Will Deacon <will.deacon@arm.com>

Catalin can pick this up for 5.1.

Will
Catalin Marinas Feb. 4, 2019, 4:55 p.m. UTC | #3
On Thu, Jan 31, 2019 at 06:23:37PM +0000, Valentin Schneider wrote:
> Since the enabling and disabling of IRQs within preempt_schedule_irq()
> is contained in a need_resched() loop, we don't need the outer arch
> code loop.
> 
> Reported-by: Julien Thierry <julien.thierry@arm.com>
> Reported-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Julien Grall <julien.grall@arm.com>
> Cc: Julien Thierry <julien.thierry@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-arm-kernel@lists.infradead.org

Queued for 5.1. Thanks
diff mbox series

Patch

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 0ec0c46b2c0c..4d0c81f29a60 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -611,7 +611,7 @@  el1_irq:
 #ifdef CONFIG_PREEMPT
 	ldr	x24, [tsk, #TSK_TI_PREEMPT]	// get preempt count
 	cbnz	x24, 1f				// preempt count != 0
-	bl	el1_preempt
+	bl	preempt_schedule_irq		// irq en/disable is done inside
 1:
 #endif
 #ifdef CONFIG_TRACE_IRQFLAGS
@@ -620,15 +620,6 @@  el1_irq:
 	kernel_exit 1
 ENDPROC(el1_irq)
 
-#ifdef CONFIG_PREEMPT
-el1_preempt:
-	mov	x24, lr
-1:	bl	preempt_schedule_irq		// irq en/disable is done inside
-	ldr	x0, [tsk, #TSK_TI_FLAGS]	// get new tasks TI_FLAGS
-	tbnz	x0, #TIF_NEED_RESCHED, 1b	// needs rescheduling?
-	ret	x24
-#endif
-
 /*
  * EL0 mode handlers.
  */