[PATCH RT 0/4] [ANNOUNCE] 3.2.19-rt31-rc1

[PATCH RT 0/4] [ANNOUNCE] 3.2.19-rt31-rc1

[Steven Rostedt]

Dear RT Folks,

This is the RT stable review cycle of patch 3.2.19-rt31-rc1.

Please scream at me if I messed something up. Please test the patches too.

The -rc release will be uploaded to kernel.org and will be deleted when
the final release is out. This is just a review release (or release candidate).

The pre-releases will not be pushed to the git repository, only the
final release is.

If all goes well, this patch will be converted to the next main release
on 6/12/2012.

Enjoy,

-- Steve


To build 3.2.19-rt31-rc1 directly, the following patches should be applied:

  http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.2.tar.xz

  http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.2.19.xz

  http://www.kernel.org/pub/linux/kernel/projects/rt/3.2/patch-3.2.19-rt31-rc1.patch.xz

You can also build from 3.2.19-rt30 by applying the incremental patch:

http://www.kernel.org/pub/linux/kernel/projects/rt/3.2/incr/patch-3.2.19-rt30-rt31-rc1.patch.xz


Changes from 3.2.19-rt30:

---


John Kacur (1):
      scsi: qla2xxx: Use local_irq_save_nort() in qla2x00_poll

Priyanka Jain (1):
      net,RT:REmove preemption disabling in netif_rx()

Steven Rostedt (1):
      Linux 3.2.19-rt31-rc1

Thomas Gleixner (1):
      mips-remove-smp-reserve-lock.patch

----
 arch/mips/cavium-octeon/smp.c     |    6 ------
 drivers/scsi/qla2xxx/qla_inline.h |    4 ++--
 localversion-rt                   |    2 +-
 net/core/dev.c                    |    8 ++++----
 4 files changed, 7 insertions(+), 13 deletions(-)

[PATCH RT 1/4] scsi: qla2xxx: Use local_irq_save_nort() in qla2x00_poll

[Steven Rostedt]

[-- Attachment #1: 0001-scsi-qla2xxx-Use-local_irq_save_nort-in-qla2x00_poll.patch --]
[-- Type: text/plain, Size: 1801 bytes --]

From: John Kacur <jkacur@redhat.com>

RT triggers the following:

[   11.307652]  [<ffffffff81077b27>] __might_sleep+0xe7/0x110
[   11.307663]  [<ffffffff8150e524>] rt_spin_lock+0x24/0x60
[   11.307670]  [<ffffffff8150da78>] ? rt_spin_lock_slowunlock+0x78/0x90
[   11.307703]  [<ffffffffa0272d83>] qla24xx_intr_handler+0x63/0x2d0 [qla2xxx]
[   11.307736]  [<ffffffffa0262307>] qla2x00_poll+0x67/0x90 [qla2xxx]

Function qla2x00_poll does local_irq_save() before calling qla24xx_intr_handler
which has a spinlock. Since spinlocks are sleepable on rt, it is not allowed
to call them with interrupts disabled. Therefore we use local_irq_save_nort()
instead which saves flags without disabling interrupts.

This fix needs to be applied to v3.0-rt, v3.2-rt and v3.4-rt

Suggested-by: Thomas Gleixner
Signed-off-by: John Kacur <jkacur@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: David Sommerseth <davids@redhat.com>
Link: http://lkml.kernel.org/r/1335523726-10024-1-git-send-email-jkacur@redhat.com
Cc: stable-rt@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 drivers/scsi/qla2xxx/qla_inline.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_inline.h b/drivers/scsi/qla2xxx/qla_inline.h
index 9902834..6d01db6 100644
--- a/drivers/scsi/qla2xxx/qla_inline.h
+++ b/drivers/scsi/qla2xxx/qla_inline.h
@@ -36,12 +36,12 @@ qla2x00_poll(struct rsp_que *rsp)
 {
 	unsigned long flags;
 	struct qla_hw_data *ha = rsp->hw;
-	local_irq_save(flags);
+	local_irq_save_nort(flags);
 	if (IS_QLA82XX(ha))
 		qla82xx_poll(0, rsp);
 	else
 		ha->isp_ops->intr_handler(0, rsp);
-	local_irq_restore(flags);
+	local_irq_restore_nort(flags);
 }
 
 static inline uint8_t *
-- 
1.7.10

[PATCH RT 2/4] net,RT:REmove preemption disabling in netif_rx()

[Steven Rostedt]

[-- Attachment #1: 0002-net-RT-REmove-preemption-disabling-in-netif_rx.patch --]
[-- Type: text/plain, Size: 2092 bytes --]

From: Priyanka Jain <Priyanka.Jain@freescale.com>

1)enqueue_to_backlog() (called from netif_rx) should be
  bind to a particluar CPU. This can be achieved by
  disabling migration. No need to disable preemption

2)Fixes crash "BUG: scheduling while atomic: ksoftirqd"
  in case of RT.
  If preemption is disabled, enqueue_to_backog() is called
  in atomic context. And if backlog exceeds its count,
  kfree_skb() is called. But in RT, kfree_skb() might
  gets scheduled out, so it expects non atomic context.

3)When CONFIG_PREEMPT_RT_FULL is not defined,
 migrate_enable(), migrate_disable() maps to
 preempt_enable() and preempt_disable(), so no
 change in functionality in case of non-RT.

-Replace preempt_enable(), preempt_disable() with
 migrate_enable(), migrate_disable() respectively
-Replace get_cpu(), put_cpu() with get_cpu_light(),
 put_cpu_light() respectively

Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Acked-by: Rajan Srivastava <Rajan.Srivastava@freescale.com>
Cc: <rostedt@goodmis.orgn>
Link: http://lkml.kernel.org/r/1337227511-2271-1-git-send-email-Priyanka.Jain@freescale.com
Cc: stable-rt@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 net/core/dev.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 811100d..578a74d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3030,7 +3030,7 @@ int netif_rx(struct sk_buff *skb)
 		struct rps_dev_flow voidflow, *rflow = &voidflow;
 		int cpu;
 
-		preempt_disable();
+		migrate_disable();
 		rcu_read_lock();
 
 		cpu = get_rps_cpu(skb->dev, skb, &rflow);
@@ -3040,13 +3040,13 @@ int netif_rx(struct sk_buff *skb)
 		ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
 
 		rcu_read_unlock();
-		preempt_enable();
+		migrate_enable();
 	}
 #else
 	{
 		unsigned int qtail;
-		ret = enqueue_to_backlog(skb, get_cpu(), &qtail);
-		put_cpu();
+		ret = enqueue_to_backlog(skb, get_cpu_light(), &qtail);
+		put_cpu_light();
 	}
 #endif
 	return ret;
-- 
1.7.10

[PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[Steven Rostedt]

[-- Attachment #1: 0003-mips-remove-smp-reserve-lock.patch.patch --]
[-- Type: text/plain, Size: 1104 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

Instead of making the lock raw, remove it as it protects nothing.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/mips/cavium-octeon/smp.c |    6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
index efcfff4..86fce15 100644
--- a/arch/mips/cavium-octeon/smp.c
+++ b/arch/mips/cavium-octeon/smp.c
@@ -257,8 +257,6 @@ DEFINE_PER_CPU(int, cpu_state);
 
 extern void fixup_irqs(void);
 
-static DEFINE_SPINLOCK(smp_reserve_lock);
-
 static int octeon_cpu_disable(void)
 {
 	unsigned int cpu = smp_processor_id();
@@ -266,8 +264,6 @@ static int octeon_cpu_disable(void)
 	if (cpu == 0)
 		return -EBUSY;
 
-	spin_lock(&smp_reserve_lock);
-
 	cpu_clear(cpu, cpu_online_map);
 	cpu_clear(cpu, cpu_callin_map);
 	local_irq_disable();
@@ -277,8 +273,6 @@ static int octeon_cpu_disable(void)
 	flush_cache_all();
 	local_flush_tlb_all();
 
-	spin_unlock(&smp_reserve_lock);
-
 	return 0;
 }
 
-- 
1.7.10

[PATCH RT 4/4] Linux 3.2.19-rt31-rc1

[Steven Rostedt]

[-- Attachment #1: 0004-Linux-3.2.19-rt31-rc1.patch --]
[-- Type: text/plain, Size: 287 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

---
 localversion-rt |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/localversion-rt b/localversion-rt
index b72862e..7f30ff7 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt30
+-rt31-rc1
-- 
1.7.10

Re: [PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[David Daney]

On 06/07/2012 12:32 PM, Steven Rostedt wrote:
> On Thu, 2012-06-07 at 12:08 -0700, David Daney wrote:
>
>>> Should it go to mainline stable?
>>>
>>
>> I don't think it is necessary.  As far as I know, RT may be the only
>> thing that needs it.
>
> Ah, you're right. As this is just an issue because it is called with
> interrupts disabled (from stop_machine). Although it's interesting that
> the mips code, re-enables interrupts from that function.
>
>  From kernel/cpu.c:
>
> _cpu_down() {
> 	 __stop_machine(take_cpu_down,&tcd_param, cpumask_of(cpu));
>
> take_cpu_down() {
> 	err = __cpu_disable();
>
> kernel/stop_machine.c:
>
> __stop_machine(int (*fn)(void *) ...) {
> 	local_irq_save(flags);
> 	hard_irq_disable();
> 	ret = (*fn)(data);
> 	local_irq_restore(flags);
>
>
> arch/mips/include/asm/smp.h:
>
> static inline int __cpu_disable(void)
> {
>          extern struct plat_smp_ops *mp_ops;     /* private */
>
>          return mp_ops->cpu_disable();
> }
>
> arch/mips/cavium-octeon/smp.c:
>
> octeon_cpu_disable(void) {
>          local_irq_disable();
>          fixup_irqs();
>          local_irq_enable();
>
> struct plat_smp_ops octeon_smp_ops = {
>          .cpu_disable            = octeon_cpu_disable,
>
>
> Is this expected? It causes the cpu notifiers to be called with
> interrupts enabled. Not sure if that's a problem or not.

I am inclined to go with your instinct here.  Probably we shouldn't 
unconditionally local_irq_enable() here.

Perhaps {,raw}_local_irq_save/{,raw}local_irq_restore would be better. 
Or even no local irq enable manipulation...

In any event, I may let Ralf sort it out.

David Daney

Re: [PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[Steven Rostedt]

On Thu, 2012-06-07 at 12:08 -0700, David Daney wrote:

> > Should it go to mainline stable?
> >
> 
> I don't think it is necessary.  As far as I know, RT may be the only 
> thing that needs it.

Ah, you're right. As this is just an issue because it is called with
interrupts disabled (from stop_machine). Although it's interesting that
the mips code, re-enables interrupts from that function.

>From kernel/cpu.c:

_cpu_down() {
	 __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));

take_cpu_down() {
	err = __cpu_disable();

kernel/stop_machine.c:

__stop_machine(int (*fn)(void *) ...) {
	local_irq_save(flags);
	hard_irq_disable();
	ret = (*fn)(data);
	local_irq_restore(flags);


arch/mips/include/asm/smp.h:

static inline int __cpu_disable(void)
{
        extern struct plat_smp_ops *mp_ops;     /* private */

        return mp_ops->cpu_disable();
}

arch/mips/cavium-octeon/smp.c:

octeon_cpu_disable(void) {
        local_irq_disable();
        fixup_irqs();
        local_irq_enable();

struct plat_smp_ops octeon_smp_ops = {
        .cpu_disable            = octeon_cpu_disable,


Is this expected? It causes the cpu notifiers to be called with
interrupts enabled. Not sure if that's a problem or not.

-- Steve

Re: [PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[David Daney]

On 06/07/2012 11:56 AM, Steven Rostedt wrote:
> On Thu, 2012-06-07 at 10:50 -0700, David Daney wrote:
>> On 06/07/2012 08:51 AM, Steven Rostedt wrote:
>>> From: Thomas Gleixner<tglx@linutronix.de>
>>>
>>> Instead of making the lock raw, remove it as it protects nothing.
>>
>> I don't know how you guys are managing the RT branch, but this seems
>> quite similar to:
>>
>> a3c8b4faeeccb33dbad6969bc9e50bf409f167e7 (MIPS: Cavium: Remove
>> smp_reserve_lock.)
>
> Great! Then we don't need to worry about it :-)
>
> But as it doesn't seem that this patch was marked as stable, we will be
> carrying it in -rt where we support older kernels.
>
> Should it go to mainline stable?
>

I don't think it is necessary.  As far as I know, RT may be the only 
thing that needs it.

David Daney

> -- Steve
>
>>
>> David Daney
>>
>
>

Re: [PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[Steven Rostedt]

On Thu, 2012-06-07 at 10:50 -0700, David Daney wrote:
> On 06/07/2012 08:51 AM, Steven Rostedt wrote:
> > From: Thomas Gleixner<tglx@linutronix.de>
> >
> > Instead of making the lock raw, remove it as it protects nothing.
> 
> I don't know how you guys are managing the RT branch, but this seems 
> quite similar to:
> 
> a3c8b4faeeccb33dbad6969bc9e50bf409f167e7 (MIPS: Cavium: Remove 
> smp_reserve_lock.)

Great! Then we don't need to worry about it :-)

But as it doesn't seem that this patch was marked as stable, we will be
carrying it in -rt where we support older kernels.

Should it go to mainline stable?

-- Steve

> 
> David Daney
> 

Re: [PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[David Daney]

On 06/07/2012 08:51 AM, Steven Rostedt wrote:
> From: Thomas Gleixner<tglx@linutronix.de>
>
> Instead of making the lock raw, remove it as it protects nothing.

I don't know how you guys are managing the RT branch, but this seems 
quite similar to:

a3c8b4faeeccb33dbad6969bc9e50bf409f167e7 (MIPS: Cavium: Remove 
smp_reserve_lock.)

David Daney


>
> Signed-off-by: Thomas Gleixner<tglx@linutronix.de>
> Cc: stable-rt@vger.kernel.org
> Signed-off-by: Steven Rostedt<rostedt@goodmis.org>
> ---
>   arch/mips/cavium-octeon/smp.c |    6 ------
>   1 file changed, 6 deletions(-)
>
> diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
> index efcfff4..86fce15 100644
> --- a/arch/mips/cavium-octeon/smp.c
> +++ b/arch/mips/cavium-octeon/smp.c
> @@ -257,8 +257,6 @@ DEFINE_PER_CPU(int, cpu_state);
>
>   extern void fixup_irqs(void);
>
> -static DEFINE_SPINLOCK(smp_reserve_lock);
> -
>   static int octeon_cpu_disable(void)
>   {
>   	unsigned int cpu = smp_processor_id();
> @@ -266,8 +264,6 @@ static int octeon_cpu_disable(void)
>   	if (cpu == 0)
>   		return -EBUSY;
>
> -	spin_lock(&smp_reserve_lock);
> -
>   	cpu_clear(cpu, cpu_online_map);
>   	cpu_clear(cpu, cpu_callin_map);
>   	local_irq_disable();
> @@ -277,8 +273,6 @@ static int octeon_cpu_disable(void)
>   	flush_cache_all();
>   	local_flush_tlb_all();
>
> -	spin_unlock(&smp_reserve_lock);
> -
>   	return 0;
>   }
>

[PATCH RT 3/4] mips-remove-smp-reserve-lock.patch

[Steven Rostedt]

[-- Attachment #1: 0003-mips-remove-smp-reserve-lock.patch.patch --]
[-- Type: text/plain, Size: 1104 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

Instead of making the lock raw, remove it as it protects nothing.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/mips/cavium-octeon/smp.c |    6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
index efcfff4..86fce15 100644
--- a/arch/mips/cavium-octeon/smp.c
+++ b/arch/mips/cavium-octeon/smp.c
@@ -257,8 +257,6 @@ DEFINE_PER_CPU(int, cpu_state);
 
 extern void fixup_irqs(void);
 
-static DEFINE_SPINLOCK(smp_reserve_lock);
-
 static int octeon_cpu_disable(void)
 {
 	unsigned int cpu = smp_processor_id();
@@ -266,8 +264,6 @@ static int octeon_cpu_disable(void)
 	if (cpu == 0)
 		return -EBUSY;
 
-	spin_lock(&smp_reserve_lock);
-
 	cpu_clear(cpu, cpu_online_map);
 	cpu_clear(cpu, cpu_callin_map);
 	local_irq_disable();
@@ -277,8 +273,6 @@ static int octeon_cpu_disable(void)
 	flush_cache_all();
 	local_flush_tlb_all();
 
-	spin_unlock(&smp_reserve_lock);
-
 	return 0;
 }
 
-- 
1.7.10