diff mbox

[tip/core/rcu,7/9] arm64: Use common outgoing-CPU-notification code

Message ID 1431467407-1223-7-git-send-email-paulmck@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Paul E. McKenney May 12, 2015, 9:50 p.m. UTC 
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

This commit removes the open-coded CPU-offline notification with new
common code.  In particular, this change avoids calling scheduler code
using RCU from an offline CPU that RCU is ignoring.  This is a minimal
change.  A more intrusive change might invoke the cpu_check_up_prepare()
and cpu_set_state_online() functions at CPU-online time, which would
allow onlining throw an error if the CPU did not go offline properly.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/kernel/smp.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Comments

Will Deacon May 21, 2015, 8:58 a.m. UTC | #1 
Hi Paul,

Sorry for being late on this one.

On Tue, May 12, 2015 at 10:50:05PM +0100, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> 
> This commit removes the open-coded CPU-offline notification with new
> common code.  In particular, this change avoids calling scheduler code
> using RCU from an offline CPU that RCU is ignoring.  This is a minimal
> change.  A more intrusive change might invoke the cpu_check_up_prepare()
> and cpu_set_state_online() functions at CPU-online time, which would
> allow onlining throw an error if the CPU did not go offline properly.
> 
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
>  arch/arm64/kernel/smp.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

I don't have a better idea, so:

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

Is this queued via -tip already, or can we pick it into the arm64 tree
for 4.2?

Cheers,

Will

> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 2cb008177252..a899c1beff54 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -253,15 +253,13 @@ static int op_cpu_kill(unsigned int cpu)
>  	return cpu_ops[cpu]->cpu_kill(cpu);
>  }
>  
> -static DECLARE_COMPLETION(cpu_died);
> -
>  /*
>   * called on the thread which is asking for a CPU to be shutdown -
>   * waits until shutdown has completed, or it is timed out.
>   */
>  void __cpu_die(unsigned int cpu)
>  {
> -	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
> +	if (!cpu_wait_death(cpu, 5)) {
>  		pr_crit("CPU%u: cpu didn't die\n", cpu);
>  		return;
>  	}
> @@ -294,7 +292,7 @@ void cpu_die(void)
>  	local_irq_disable();
>  
>  	/* Tell __cpu_die() that this CPU is now safe to dispose of */
> -	complete(&cpu_died);
> +	(void)cpu_report_death();
>  
>  	/*
>  	 * Actually shutdown the CPU. This must never fail. The specific hotplug
> -- 
> 1.8.1.5
>
Paul E. McKenney May 21, 2015, 12:48 p.m. UTC | #2 
On Thu, May 21, 2015 at 09:58:06AM +0100, Will Deacon wrote:
> Hi Paul,
> 
> Sorry for being late on this one.

No problem!  In fact, just in time -- I was going to bug you about
this later today.  ;-)

> On Tue, May 12, 2015 at 10:50:05PM +0100, Paul E. McKenney wrote:
> > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > 
> > This commit removes the open-coded CPU-offline notification with new
> > common code.  In particular, this change avoids calling scheduler code
> > using RCU from an offline CPU that RCU is ignoring.  This is a minimal
> > change.  A more intrusive change might invoke the cpu_check_up_prepare()
> > and cpu_set_state_online() functions at CPU-online time, which would
> > allow onlining throw an error if the CPU did not go offline properly.
> > 
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will.deacon@arm.com>
> > ---
> >  arch/arm64/kernel/smp.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> I don't have a better idea, so:
> 
>   Acked-by: Will Deacon <will.deacon@arm.com>
> 
> Is this queued via -tip already, or can we pick it into the arm64 tree
> for 4.2?

Feel free to take it into the arm64 tree.  Just let me know, and I
will drop it from my tree.

Now I only need to bug the arm32 guys.  ;-)

							Thanx, Paul

> Cheers,
> 
> Will
> 
> > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > index 2cb008177252..a899c1beff54 100644
> > --- a/arch/arm64/kernel/smp.c
> > +++ b/arch/arm64/kernel/smp.c
> > @@ -253,15 +253,13 @@ static int op_cpu_kill(unsigned int cpu)
> >  	return cpu_ops[cpu]->cpu_kill(cpu);
> >  }
> >  
> > -static DECLARE_COMPLETION(cpu_died);
> > -
> >  /*
> >   * called on the thread which is asking for a CPU to be shutdown -
> >   * waits until shutdown has completed, or it is timed out.
> >   */
> >  void __cpu_die(unsigned int cpu)
> >  {
> > -	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
> > +	if (!cpu_wait_death(cpu, 5)) {
> >  		pr_crit("CPU%u: cpu didn't die\n", cpu);
> >  		return;
> >  	}
> > @@ -294,7 +292,7 @@ void cpu_die(void)
> >  	local_irq_disable();
> >  
> >  	/* Tell __cpu_die() that this CPU is now safe to dispose of */
> > -	complete(&cpu_died);
> > +	(void)cpu_report_death();
> >  
> >  	/*
> >  	 * Actually shutdown the CPU. This must never fail. The specific hotplug
> > -- 
> > 1.8.1.5
> > 
>
Catalin Marinas May 21, 2015, 1:25 p.m. UTC | #3 
On Thu, May 21, 2015 at 05:48:33AM -0700, Paul E. McKenney wrote:
> On Thu, May 21, 2015 at 09:58:06AM +0100, Will Deacon wrote:
> > On Tue, May 12, 2015 at 10:50:05PM +0100, Paul E. McKenney wrote:
> > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > > 
> > > This commit removes the open-coded CPU-offline notification with new
> > > common code.  In particular, this change avoids calling scheduler code
> > > using RCU from an offline CPU that RCU is ignoring.  This is a minimal
> > > change.  A more intrusive change might invoke the cpu_check_up_prepare()
> > > and cpu_set_state_online() functions at CPU-online time, which would
> > > allow onlining throw an error if the CPU did not go offline properly.
> > > 
> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > > Cc: linux-arm-kernel@lists.infradead.org
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Will Deacon <will.deacon@arm.com>
> > > ---
> > >  arch/arm64/kernel/smp.c | 6 ++----
> > >  1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > I don't have a better idea, so:
> > 
> >   Acked-by: Will Deacon <will.deacon@arm.com>
> > 
> > Is this queued via -tip already, or can we pick it into the arm64 tree
> > for 4.2?
> 
> Feel free to take it into the arm64 tree.  Just let me know, and I
> will drop it from my tree.

Queued for 4.2. Thanks.
Paul E. McKenney May 22, 2015, 3:26 a.m. UTC | #4 
On Thu, May 21, 2015 at 02:25:57PM +0100, Catalin Marinas wrote:
> On Thu, May 21, 2015 at 05:48:33AM -0700, Paul E. McKenney wrote:
> > On Thu, May 21, 2015 at 09:58:06AM +0100, Will Deacon wrote:
> > > On Tue, May 12, 2015 at 10:50:05PM +0100, Paul E. McKenney wrote:
> > > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > > > 
> > > > This commit removes the open-coded CPU-offline notification with new
> > > > common code.  In particular, this change avoids calling scheduler code
> > > > using RCU from an offline CPU that RCU is ignoring.  This is a minimal
> > > > change.  A more intrusive change might invoke the cpu_check_up_prepare()
> > > > and cpu_set_state_online() functions at CPU-online time, which would
> > > > allow onlining throw an error if the CPU did not go offline properly.
> > > > 
> > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > > > Cc: linux-arm-kernel@lists.infradead.org
> > > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > > Cc: Will Deacon <will.deacon@arm.com>
> > > > ---
> > > >  arch/arm64/kernel/smp.c | 6 ++----
> > > >  1 file changed, 2 insertions(+), 4 deletions(-)
> > > 
> > > I don't have a better idea, so:
> > > 
> > >   Acked-by: Will Deacon <will.deacon@arm.com>
> > > 
> > > Is this queued via -tip already, or can we pick it into the arm64 tree
> > > for 4.2?
> > 
> > Feel free to take it into the arm64 tree.  Just let me know, and I
> > will drop it from my tree.
> 
> Queued for 4.2. Thanks.

Very good, dropped from my tree.

							Thanx, Paul
diff mbox

Patch

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 2cb008177252..a899c1beff54 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -253,15 +253,13 @@  static int op_cpu_kill(unsigned int cpu)
 	return cpu_ops[cpu]->cpu_kill(cpu);
 }
 
-static DECLARE_COMPLETION(cpu_died);
-
 /*
  * called on the thread which is asking for a CPU to be shutdown -
  * waits until shutdown has completed, or it is timed out.
  */
 void __cpu_die(unsigned int cpu)
 {
-	if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
+	if (!cpu_wait_death(cpu, 5)) {
 		pr_crit("CPU%u: cpu didn't die\n", cpu);
 		return;
 	}
@@ -294,7 +292,7 @@  void cpu_die(void)
 	local_irq_disable();
 
 	/* Tell __cpu_die() that this CPU is now safe to dispose of */
-	complete(&cpu_died);
+	(void)cpu_report_death();
 
 	/*
 	 * Actually shutdown the CPU. This must never fail. The specific hotplug