[PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[Priyanka Jain]

In ret_from_except_lite() with CONFIG_PREEMPT enabled,
add the missing check to compare value of preempt_count
with zero before continuing with preemption process of
the current task.
If preempt_count is non-zero, restore reg and return,
else continue the preemption process.

Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Fixes CQ:ENGR257848
	 CONFIG_PREEMPT_RT_FULL does not work on 64-bit
---
 arch/powerpc/kernel/entry_64.S |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 1b1c8ae..ec120e6 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -643,6 +643,8 @@ resume_kernel:
 #ifdef CONFIG_PREEMPT
 	/* Check if we need to preempt */
 	lwz	r8,TI_PREEMPT(r9)
+	cmpwi	0,r8,0		/* if non-zero, just restore regs and return */
+	bne	restore
 	andi.	r0,r4,_TIF_NEED_RESCHED
 	bne+	check_count
 
-- 
1.7.4.1

[PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[Priyanka Jain]

In ret_from_except_lite() with CONFIG_PREEMPT enabled,
add the missing check to compare value of preempt_count
with zero before continuing with preemption process of
the current task.
If preempt_count is non-zero, restore reg and return,
else continue the preemption process.

Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
---
 arch/powerpc/kernel/entry_64.S |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 1b1c8ae..ec120e6 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -643,6 +643,8 @@ resume_kernel:
 #ifdef CONFIG_PREEMPT
 	/* Check if we need to preempt */
 	lwz	r8,TI_PREEMPT(r9)
+	cmpwi	0,r8,0		/* if non-zero, just restore regs and return */
+	bne	restore
 	andi.	r0,r4,_TIF_NEED_RESCHED
 	bne+	check_count
 
-- 
1.7.4.1

RE: [PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[Jain Priyanka-B32167]

Please ignore this patch. I have send another patch with updated description.

> -----Original Message-----
> From: Jain Priyanka-B32167
> Sent: Monday, April 15, 2013 11:17 AM
> To: linux-rt-users@vger.kernel.org
> Cc: Jain Priyanka-B32167
> Subject: [PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before
> preempting
> 
> In ret_from_except_lite() with CONFIG_PREEMPT enabled, add the missing
> check to compare value of preempt_count with zero before continuing with
> preemption process of the current task.
> If preempt_count is non-zero, restore reg and return, else continue the
> preemption process.
> 
> Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com> Fixes
> CQ:ENGR257848
> 	 CONFIG_PREEMPT_RT_FULL does not work on 64-bit
> ---
>  arch/powerpc/kernel/entry_64.S |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/entry_64.S
> b/arch/powerpc/kernel/entry_64.S index 1b1c8ae..ec120e6 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -643,6 +643,8 @@ resume_kernel:
>  #ifdef CONFIG_PREEMPT
>  	/* Check if we need to preempt */
>  	lwz	r8,TI_PREEMPT(r9)
> +	cmpwi	0,r8,0		/* if non-zero, just restore regs and
> return */
> +	bne	restore
>  	andi.	r0,r4,_TIF_NEED_RESCHED
>  	bne+	check_count
> 
> --
> 1.7.4.1

Re: [PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[Sebastian Andrzej Siewior]

* Priyanka Jain | 2013-04-15 11:18:16 [+0530]:

>Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
>---
> arch/powerpc/kernel/entry_64.S |    2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
>diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
>index 1b1c8ae..ec120e6 100644
>--- a/arch/powerpc/kernel/entry_64.S
>+++ b/arch/powerpc/kernel/entry_64.S
>@@ -643,6 +643,8 @@ resume_kernel:
> #ifdef CONFIG_PREEMPT
> 	/* Check if we need to preempt */
> 	lwz	r8,TI_PREEMPT(r9)
>+	cmpwi	0,r8,0		/* if non-zero, just restore regs and return */
>+	bne	restore
> 	andi.	r0,r4,_TIF_NEED_RESCHED
> 	bne+	check_count

Oh boy oh boy. Thanks for caching this. Steven please take this to v3.6,
don't see this chunk in v3.4.

Priyanka: does 64bit power work fine on v3.6/v3.8 besides this?

Sebastian

RE: [PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before preempting

[Jain Priyanka-B32167]

Hi,

I am working on v3.8 for 64-bit powerpc. 
I have seen no other issue so far.
Able to boot Linux, run IPV4-fwd traffic.  Currently running some stress test cases.

Regards
Priyanka

> -----Original Message-----
> From: Sebastian Andrzej Siewior [mailto:bigeasy@linutronix.de]
> Sent: Thursday, April 25, 2013 10:28 PM
> To: Jain Priyanka-B32167
> Cc: linux-rt-users@vger.kernel.org; rostedt@goodmis.org
> Subject: Re: [PATCH] powerpc/64bit,PREEMPT_RT: Check preempt_count before
> preempting
> 
> * Priyanka Jain | 2013-04-15 11:18:16 [+0530]:
> 
> >Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
> >---
> > arch/powerpc/kernel/entry_64.S |    2 ++
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> >diff --git a/arch/powerpc/kernel/entry_64.S
> >b/arch/powerpc/kernel/entry_64.S index 1b1c8ae..ec120e6 100644
> >--- a/arch/powerpc/kernel/entry_64.S
> >+++ b/arch/powerpc/kernel/entry_64.S
> >@@ -643,6 +643,8 @@ resume_kernel:
> > #ifdef CONFIG_PREEMPT
> > 	/* Check if we need to preempt */
> > 	lwz	r8,TI_PREEMPT(r9)
> >+	cmpwi	0,r8,0		/* if non-zero, just restore regs and
> return */
> >+	bne	restore
> > 	andi.	r0,r4,_TIF_NEED_RESCHED
> > 	bne+	check_count
> 
> Oh boy oh boy. Thanks for caching this. Steven please take this to v3.6,
> don't see this chunk in v3.4.
> 
> Priyanka: does 64bit power work fine on v3.6/v3.8 besides this?
> 
> Sebastian