Re: [PATCH 1/1] sparc: task_cpu() for stopper thread on sparc32 returns 0

Re: [PATCH 1/1] sparc: task_cpu() for stopper thread on sparc32 returns 0

[Sam Ravnborg]

Added a few more people - as this patch touches a core file.

I expect we have an issue on sparc32 - that manifest
in this bug. But I do not know this code at all.

	Sam

On Thu, Apr 19, 2012 at 11:22:42AM +0200, Konrad Eisele wrote:
> The stopper thread for CPU > 0 (at least in sparc32)
> has on initialization task_cpu() set to zero even
> for CPUs > 0. The patch explicitly checks weather the
> CPU is allowed to run on the cpu that task_cpu()
> return or changes the return cpu.
> 
> Signed-off-by: Konrad Eisele <konrad@gaisler.com>
> ---
>  kernel/sched/stop_task.c |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
> index 7b386e8..9201866 100644
> --- a/kernel/sched/stop_task.c
> +++ b/kernel/sched/stop_task.c
> @@ -13,7 +13,14 @@
>  static int
>  select_task_rq_stop(struct task_struct *p, int sd_flag, int flags)
>  {
> -	return task_cpu(p); /* stop tasks as never migrate */
> +	int ccpu, cpu , dcpu;
> +	ccpu = cpu = task_cpu(p);
> +	if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))) {
> +		cpu = cpumask_first(tsk_cpus_allowed(p));
> +		if (cpu >= nr_cpu_ids)
> +			cpu = ccpu;
> +	}
> +	return cpu;
>  }
>  #endif /* CONFIG_SMP */
>  
> -- 
> 1.6.1.3
> 

Re: [PATCH 1/1] sparc: task_cpu() for stopper thread on sparc32 returns 0

[Yong Zhang]

On Thu, Apr 19, 2012 at 05:34:28PM +0200, Sam Ravnborg wrote:
> Added a few more people - as this patch touches a core file.
> 
> I expect we have an issue on sparc32 - that manifest
> in this bug. But I do not know this code at all.
> 
> 	Sam
> 
> On Thu, Apr 19, 2012 at 11:22:42AM +0200, Konrad Eisele wrote:
> > The stopper thread for CPU > 0 (at least in sparc32)
> > has on initialization task_cpu() set to zero even
> > for CPUs > 0. The patch explicitly checks weather the
> > CPU is allowed to run on the cpu that task_cpu()
> > return or changes the return cpu.

Actually try_to_wake_up() will put the task to the right place.

Could you please try the following patch? (Hope I'm putting
notify_cpu_starting() in the right place).

---
From: Yong Zhang <yong.zhang@windriver.com>
Date: Fri, 20 Apr 2012 11:31:45 +0800
Subject: [PATCH] sparc32,leon: add notify_cpu_starting()

Otherwise cpu_active_mask will not set, which lead to other issue.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
---
 arch/sparc/kernel/leon_smp.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
index 1210fde..bb017e7 100644
--- a/arch/sparc/kernel/leon_smp.c
+++ b/arch/sparc/kernel/leon_smp.c
@@ -78,6 +78,8 @@ void __cpuinit leon_callin(void)
 	local_flush_tlb_all();
 	leon_configure_cache_smp();
 
+	notify_cpu_starting(cpuid);
+
 	/* Get our local ticker going. */
 	smp_setup_percpu_timer();
 
-- 
1.7.5.4

Re: [PATCH 1/1] sparc: task_cpu() for stopper thread on sparc32 returns 0

[David Miller]

From: Yong Zhang <yong.zhang0@gmail.com>
Date: Fri, 20 Apr 2012 11:36:34 +0800

> diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
> index 1210fde..bb017e7 100644
> --- a/arch/sparc/kernel/leon_smp.c
> +++ b/arch/sparc/kernel/leon_smp.c
> @@ -78,6 +78,8 @@ void __cpuinit leon_callin(void)
>  	local_flush_tlb_all();
>  	leon_configure_cache_smp();
>  
> +	notify_cpu_starting(cpuid);
> +

This is the most reasonable theory I've seen for this
problem :-)

[PATCH 1/1] sparc32,leon: add notify_cpu_starting()

[Konrad Eisele]

From: Yong Zhang <yong.zhang@windriver.com>

Otherwise cpu_active_mask will not set, which lead to other issue.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Konrad Eisele <konrad@gaisler.com>
---
 arch/sparc/kernel/leon_smp.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
index 1210fde..160cac9 100644
--- a/arch/sparc/kernel/leon_smp.c
+++ b/arch/sparc/kernel/leon_smp.c
@@ -23,6 +23,7 @@
 #include <linux/pm.h>
 #include <linux/delay.h>
 #include <linux/gfp.h>
+#include <linux/cpu.h>
 
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
@@ -78,6 +79,8 @@ void __cpuinit leon_callin(void)
 	local_flush_tlb_all();
 	leon_configure_cache_smp();
 
+	notify_cpu_starting(cpuid);
+
 	/* Get our local ticker going. */
 	smp_setup_percpu_timer();
 
-- 
1.6.1.3

Re: [PATCH 1/1] sparc32,leon: add notify_cpu_starting()

[Konrad Eisele]

Hello Yong,
Thank you for the patch, it works. The SMP is fully
functional again for sparc-leon. I just added a "#include<linux/cpu.h>"
to avoid compiler warning.
Please someone in the cc-list, apply.
-- Greetings Konrad

Konrad Eisele wrote:
> From: Yong Zhang<yong.zhang@windriver.com>
>
> Otherwise cpu_active_mask will not set, which lead to other issue.
>
> Signed-off-by: Yong Zhang<yong.zhang0@gmail.com>
> Signed-off-by: Konrad Eisele<konrad@gaisler.com>
> ---
>   arch/sparc/kernel/leon_smp.c |    3 +++
>   1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
> index 1210fde..160cac9 100644
> --- a/arch/sparc/kernel/leon_smp.c
> +++ b/arch/sparc/kernel/leon_smp.c
> @@ -23,6 +23,7 @@
>   #include<linux/pm.h>
>   #include<linux/delay.h>
>   #include<linux/gfp.h>
> +#include<linux/cpu.h>
>
>   #include<asm/cacheflush.h>
>   #include<asm/tlbflush.h>
> @@ -78,6 +79,8 @@ void __cpuinit leon_callin(void)
>   	local_flush_tlb_all();
>   	leon_configure_cache_smp();
>
> +	notify_cpu_starting(cpuid);
> +
>   	/* Get our local ticker going. */
>   	smp_setup_percpu_timer();
>

Re: [PATCH 1/1] sparc32,leon: add notify_cpu_starting()

[David Miller]

From: Konrad Eisele <konrad@gaisler.com>
Date: Fri, 20 Apr 2012 08:32:50 +0200

> Hello Yong,
> Thank you for the patch, it works. The SMP is fully
> functional again for sparc-leon. I just added a
> "#include<linux/cpu.h>"
> to avoid compiler warning.
> Please someone in the cc-list, apply.

I'll take care of it.

[PATCH] sparc32,leon: add notify_cpu_starting()

[Konrad Eisele]

Otherwise cpu_active_mask will not set, which lead to other issue.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Konrad Eisele <konrad@gaisler.com>
---
 arch/sparc/kernel/leon_smp.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
index 6173f4d..356dfc4 100644
--- a/arch/sparc/kernel/leon_smp.c
+++ b/arch/sparc/kernel/leon_smp.c
@@ -79,6 +79,8 @@ void __cpuinit leon_callin(void)
 	local_flush_tlb_all();
 	leon_configure_cache_smp();
 
+	notify_cpu_starting(cpuid);
+
 	/* Get our local ticker going. */
 	register_percpu_ce(cpuid);
 
-- 
1.6.1.3

Re: [PATCH] sparc32,leon: add notify_cpu_starting()

[Konrad Eisele]

This version is against linux/kernel/git/davem/sparc-next.git .
-- Konrad

Konrad Eisele wrote:
> Otherwise cpu_active_mask will not set, which lead to other issue.
>
> Signed-off-by: Yong Zhang<yong.zhang0@gmail.com>
> Signed-off-by: Konrad Eisele<konrad@gaisler.com>
> ---
>   arch/sparc/kernel/leon_smp.c |    2 ++
>   1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
> index 6173f4d..356dfc4 100644
> --- a/arch/sparc/kernel/leon_smp.c
> +++ b/arch/sparc/kernel/leon_smp.c
> @@ -79,6 +79,8 @@ void __cpuinit leon_callin(void)
>   	local_flush_tlb_all();
>   	leon_configure_cache_smp();
>
> +	notify_cpu_starting(cpuid);
> +
>   	/* Get our local ticker going. */
>   	register_percpu_ce(cpuid);
>

Re: [PATCH] sparc32,leon: add notify_cpu_starting()

[Srivatsa S. Bhat]

On 04/20/2012 01:16 PM, Konrad Eisele wrote:

> Otherwise cpu_active_mask will not set, which lead to other issue.
> 
> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
> Signed-off-by: Konrad Eisele <konrad@gaisler.com>


Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>

Looks like I missed sparc32 while fixing up the other architectures.
(https://lkml.org/lkml/2012/3/22/132)

Regards,
Srivatsa S. Bhat

> ---
>  arch/sparc/kernel/leon_smp.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
> index 6173f4d..356dfc4 100644
> --- a/arch/sparc/kernel/leon_smp.c
> +++ b/arch/sparc/kernel/leon_smp.c
> @@ -79,6 +79,8 @@ void __cpuinit leon_callin(void)
>  	local_flush_tlb_all();
>  	leon_configure_cache_smp();
> 
> +	notify_cpu_starting(cpuid);
> +
>  	/* Get our local ticker going. */
>  	register_percpu_ce(cpuid);
>