ARM: smp: why don't eliminate warning "Unknown IPI message 0x1"?

ARM: smp: why don't eliminate warning "Unknown IPI message 0x1"?

[湛振波]

Russell King want people to move to SGI0 for this, so that we can have SGI1-N
as the proper IPIs, but now we can't do this, maybe we must wait for
so many years.
But, Do you think we can use a another way to resolve this problem,
because this warning message will oftenly appeare in products.

We can't assume the fixed IPI number that can wakeup secondary cores.
"I'd much rather see platforms deciding whether they need to use SGI1
or whether they can switch to SGI0 instead."

Just give one ugly idea. I have modify this for example in msm platform.
Pls check the attached git diff patch Or below lines and give your suggestions
-------------- next part --------------
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index ea73045..8605400 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -25,6 +25,7 @@
 #include <linux/percpu.h>
 #include <linux/clockchips.h>
 #include <linux/completion.h>
+#include <linux/threads.h>
 
 #include <linux/atomic.h>
 #include <asm/cacheflush.h>
@@ -495,11 +496,28 @@ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 	handle_IPI(ipinr, regs);
 }
 
+static int ipi_wakeup_nr[NR_CPUS];
+
+void smp_send_wakeup_ipi_begin(unsigned int cpu, unsigned int irq)
+{
+	ipi_wakeup_nr[cpu] = irq + 1;
+	gic_raise_softirq(cpumask_of(cpu),irq);
+}
+
+void smp_send_wakeup_ipi_end(unsigned int cpu, unsigned int irq)
+{
+	BUG_ON(ipi_wakeup_nr[cpu] != irq + 1);
+	ipi_wakeup_nr[cpu] = 0;
+}
+
 void handle_IPI(int ipinr, struct pt_regs *regs)
 {
 	unsigned int cpu = smp_processor_id();
 	struct pt_regs *old_regs = set_irq_regs(regs);
 
+	if (ipi_wakeup_nr[cpu] == ipinr + 1)
+		goto Exit;
+
 	if (ipinr >= IPI_TIMER && ipinr < IPI_TIMER + NR_IPI)
 		__inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_TIMER]);
 
@@ -537,6 +555,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 		       cpu, ipinr);
 		break;
 	}
+Exit:	
 	set_irq_regs(old_regs);
 }
 

ARM: smp: why don't eliminate warning "Unknown IPI message 0x1"?

[steve.zhan]

Below is the whole of the patch.

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index ea73045..8605400 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -25,6 +25,7 @@
 #include <linux/percpu.h>
 #include <linux/clockchips.h>
 #include <linux/completion.h>
+#include <linux/threads.h>

 #include <linux/atomic.h>
 #include <asm/cacheflush.h>
@@ -495,11 +496,28 @@ asmlinkage void __exception_irq_entry do_IPI(int
ipinr, struct pt_regs *regs)
        handle_IPI(ipinr, regs);
 }

+static int ipi_wakeup_nr[NR_CPUS];
+
+void smp_send_wakeup_ipi_begin(unsigned int cpu, unsigned int irq)
+{
+       ipi_wakeup_nr[cpu] = irq + 1;
+       gic_raise_softirq(cpumask_of(cpu),irq);
+}
+
+void smp_send_wakeup_ipi_end(unsigned int cpu, unsigned int irq)
+{
+       BUG_ON(ipi_wakeup_nr[cpu] != irq + 1);
+       ipi_wakeup_nr[cpu] = 0;
+}
+
 void handle_IPI(int ipinr, struct pt_regs *regs)
 {
        unsigned int cpu = smp_processor_id();
        struct pt_regs *old_regs = set_irq_regs(regs);

+       if (ipi_wakeup_nr[cpu] == ipinr + 1)
+               goto Exit;
+
        if (ipinr >= IPI_TIMER && ipinr < IPI_TIMER + NR_IPI)
                __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_TIMER]);

@@ -537,6 +555,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
                       cpu, ipinr);
                break;
        }
+Exit:
        set_irq_regs(old_regs);
 }

diff --git a/arch/arm/mach-msm/platsmp.c b/arch/arm/mach-msm/platsmp.c
index db0117e..ecc6add 100644
--- a/arch/arm/mach-msm/platsmp.c
+++ b/arch/arm/mach-msm/platsmp.c
@@ -127,7 +127,7 @@ int __cpuinit boot_secondary(unsigned int cpu,
struct task_struct *idle)
         * the boot monitor to read the system wide flags register,
         * and branch to the address found there.
         */
-       gic_raise_softirq(cpumask_of(cpu), 1);
+       smp_send_wakeup_ipi_begin(cpu, 0);

        timeout = jiffies + (1 * HZ);
        while (time_before(jiffies, timeout)) {
@@ -137,6 +137,7 @@ int __cpuinit boot_secondary(unsigned int cpu,
struct task_struct *idle)

                udelay(10);
        }
+       smp_send_wakeup_ipi_end(cpu, 0);

        /*
         * now the secondary core is starting up let it run its


2012/9/18, ??? <zhanzhenbo@gmail.com>:
> Russell King want people to move to SGI0 for this, so that we can have
> SGI1-N
> as the proper IPIs, but now we can't do this, maybe we must wait for
> so many years.
> But, Do you think we can use a another way to resolve this problem,
> because this warning message will oftenly appeare in products.
>
> We can't assume the fixed IPI number that can wakeup secondary cores.
> "I'd much rather see platforms deciding whether they need to use SGI1
> or whether they can switch to SGI0 instead."
>
> Just give one ugly idea. I have modify this for example in msm platform.
> Pls check the attached git diff patch Or below lines and give your
> suggestions
>


-- 
Steve Zhan

ARM: smp: why don't eliminate warning "Unknown IPI message 0x1"?

[Russell King - ARM Linux]

On Tue, Sep 18, 2012 at 04:07:49PM +0800, ??? wrote:
> Russell King want people to move to SGI0 for this, so that we can have SGI1-N
> as the proper IPIs, but now we can't do this, maybe we must wait for
> so many years.
> But, Do you think we can use a another way to resolve this problem,
> because this warning message will oftenly appeare in products.
> 
> We can't assume the fixed IPI number that can wakeup secondary cores.
> "I'd much rather see platforms deciding whether they need to use SGI1
> or whether they can switch to SGI0 instead."

Why not just fix your platform to use SGI0.  I think we're _finally_
there with everyone using SGI0, which means we can commit the patch
which fixes this.

And anyway, how many of your customers read your kernel log messages?

ARM: smp: why don't eliminate warning "Unknown IPI message 0x1"?

[Stephen Boyd]

On 09/18/12 02:38, Russell King - ARM Linux wrote:
> On Tue, Sep 18, 2012 at 04:07:49PM +0800, ??? wrote:
>> Russell King want people to move to SGI0 for this, so that we can have SGI1-N
>> as the proper IPIs, but now we can't do this, maybe we must wait for
>> so many years.
>> But, Do you think we can use a another way to resolve this problem,
>> because this warning message will oftenly appeare in products.
>>
>> We can't assume the fixed IPI number that can wakeup secondary cores.
>> "I'd much rather see platforms deciding whether they need to use SGI1
>> or whether they can switch to SGI0 instead."
> Why not just fix your platform to use SGI0.  I think we're _finally_
> there with everyone using SGI0, which means we can commit the patch
> which fixes this.
>

Yes. I'm going to put it in the patch tracker now.

https://patchwork.kernel.org/patch/1433931/

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