Re: [PATCH] x86/apic: Move pending intr check code into it's own function

[Andy Shevchenko]

On Wed, Feb 14, 2018 at 8:24 AM, Dou Liyang  wrote:

Yes, I see you just moved the old code, but it might make sense to
update later the following.

> +   for (j = 31; j >= 0; j--) {
> +   if (value & (1< +   ack_APIC_irq();
> +   acked++;
> +   }
> +   }

> +   printk(KERN_ERR "LAPIC pending interrupts after %d 
> EOI\n",
> +  acked);

pr_err()

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] x86/apic: Move pending intr check code into it's own function

[Andy Shevchenko]

On Wed, Feb 14, 2018 at 8:24 AM, Dou Liyang  wrote:

Yes, I see you just moved the old code, but it might make sense to
update later the following.

> +   for (j = 31; j >= 0; j--) {
> +   if (value & (1< +   ack_APIC_irq();
> +   acked++;
> +   }
> +   }

> +   printk(KERN_ERR "LAPIC pending interrupts after %d 
> EOI\n",
> +  acked);

pr_err()

-- 
With Best Regards,
Andy Shevchenko

[PATCH] x86/apic: Move pending intr check code into it's own function

[Dou Liyang]

the pending interrupt check code is mixed with the local APIC setup code,
that looks messy.

Extract the related code, move it into a new function named
apic_pending_intr_clear().

Signed-off-by: Dou Liyang 
---
 arch/x86/kernel/apic/apic.c | 98 -
 1 file changed, 52 insertions(+), 46 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 3fc259b4dd2d..6f59ac2238ab 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1408,6 +1408,56 @@ static void lapic_setup_esr(void)
oldvalue, value);
 }
 
+static void apic_pending_intr_clear(void)
+{
+   long long max_loops = cpu_khz ? cpu_khz : 100;
+   unsigned long long tsc = 0, ntsc;
+   unsigned int value, queued;
+   int i, j, acked = 0;
+
+   if (boot_cpu_has(X86_FEATURE_TSC))
+   tsc = rdtsc();
+   /*
+* After a crash, we no longer service the interrupts and a pending
+* interrupt from previous kernel might still have ISR bit set.
+*
+* Most probably by now CPU has serviced that pending interrupt and
+* it might not have done the ack_APIC_irq() because it thought,
+* interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
+* does not clear the ISR bit and cpu thinks it has already serivced
+* the interrupt. Hence a vector might get locked. It was noticed
+* for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
+*/
+   do {
+   queued = 0;
+   for (i = APIC_ISR_NR - 1; i >= 0; i--)
+   queued |= apic_read(APIC_IRR + i*0x10);
+
+   for (i = APIC_ISR_NR - 1; i >= 0; i--) {
+   value = apic_read(APIC_ISR + i*0x10);
+   for (j = 31; j >= 0; j--) {
+   if (value & (1< 256) {
+   printk(KERN_ERR "LAPIC pending interrupts after %d 
EOI\n",
+  acked);
+   break;
+   }
+   if (queued) {
+   if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
+   ntsc = rdtsc();
+   max_loops = (cpu_khz << 10) - (ntsc - tsc);
+   } else
+   max_loops--;
+   }
+   } while (queued && max_loops > 0);
+   WARN_ON(max_loops <= 0);
+}
+
 /**
  * setup_local_APIC - setup the local APIC
  *
@@ -1417,13 +1467,7 @@ static void lapic_setup_esr(void)
 void setup_local_APIC(void)
 {
int cpu = smp_processor_id();
-   unsigned int value, queued;
-   int i, j, acked = 0;
-   unsigned long long tsc = 0, ntsc;
-   long long max_loops = cpu_khz ? cpu_khz : 100;
-
-   if (boot_cpu_has(X86_FEATURE_TSC))
-   tsc = rdtsc();
+   unsigned int value;
 
if (disable_apic) {
disable_ioapic_support();
@@ -1475,45 +1519,7 @@ void setup_local_APIC(void)
value &= ~APIC_TPRI_MASK;
apic_write(APIC_TASKPRI, value);
 
-   /*
-* After a crash, we no longer service the interrupts and a pending
-* interrupt from previous kernel might still have ISR bit set.
-*
-* Most probably by now CPU has serviced that pending interrupt and
-* it might not have done the ack_APIC_irq() because it thought,
-* interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
-* does not clear the ISR bit and cpu thinks it has already serivced
-* the interrupt. Hence a vector might get locked. It was noticed
-* for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
-*/
-   do {
-   queued = 0;
-   for (i = APIC_ISR_NR - 1; i >= 0; i--)
-   queued |= apic_read(APIC_IRR + i*0x10);
-
-   for (i = APIC_ISR_NR - 1; i >= 0; i--) {
-   value = apic_read(APIC_ISR + i*0x10);
-   for (j = 31; j >= 0; j--) {
-   if (value & (1< 256) {
-   printk(KERN_ERR "LAPIC pending interrupts after %d 
EOI\n",
-  acked);
-   break;
-   }
-   if (queued) {
-   if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
-   ntsc = rdtsc();
-   

[PATCH] x86/apic: Move pending intr check code into it's own function

[Dou Liyang]

the pending interrupt check code is mixed with the local APIC setup code,
that looks messy.

Extract the related code, move it into a new function named
apic_pending_intr_clear().

Signed-off-by: Dou Liyang 
---
 arch/x86/kernel/apic/apic.c | 98 -
 1 file changed, 52 insertions(+), 46 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 3fc259b4dd2d..6f59ac2238ab 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1408,6 +1408,56 @@ static void lapic_setup_esr(void)
oldvalue, value);
 }
 
+static void apic_pending_intr_clear(void)
+{
+   long long max_loops = cpu_khz ? cpu_khz : 100;
+   unsigned long long tsc = 0, ntsc;
+   unsigned int value, queued;
+   int i, j, acked = 0;
+
+   if (boot_cpu_has(X86_FEATURE_TSC))
+   tsc = rdtsc();
+   /*
+* After a crash, we no longer service the interrupts and a pending
+* interrupt from previous kernel might still have ISR bit set.
+*
+* Most probably by now CPU has serviced that pending interrupt and
+* it might not have done the ack_APIC_irq() because it thought,
+* interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
+* does not clear the ISR bit and cpu thinks it has already serivced
+* the interrupt. Hence a vector might get locked. It was noticed
+* for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
+*/
+   do {
+   queued = 0;
+   for (i = APIC_ISR_NR - 1; i >= 0; i--)
+   queued |= apic_read(APIC_IRR + i*0x10);
+
+   for (i = APIC_ISR_NR - 1; i >= 0; i--) {
+   value = apic_read(APIC_ISR + i*0x10);
+   for (j = 31; j >= 0; j--) {
+   if (value & (1< 256) {
+   printk(KERN_ERR "LAPIC pending interrupts after %d 
EOI\n",
+  acked);
+   break;
+   }
+   if (queued) {
+   if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
+   ntsc = rdtsc();
+   max_loops = (cpu_khz << 10) - (ntsc - tsc);
+   } else
+   max_loops--;
+   }
+   } while (queued && max_loops > 0);
+   WARN_ON(max_loops <= 0);
+}
+
 /**
  * setup_local_APIC - setup the local APIC
  *
@@ -1417,13 +1467,7 @@ static void lapic_setup_esr(void)
 void setup_local_APIC(void)
 {
int cpu = smp_processor_id();
-   unsigned int value, queued;
-   int i, j, acked = 0;
-   unsigned long long tsc = 0, ntsc;
-   long long max_loops = cpu_khz ? cpu_khz : 100;
-
-   if (boot_cpu_has(X86_FEATURE_TSC))
-   tsc = rdtsc();
+   unsigned int value;
 
if (disable_apic) {
disable_ioapic_support();
@@ -1475,45 +1519,7 @@ void setup_local_APIC(void)
value &= ~APIC_TPRI_MASK;
apic_write(APIC_TASKPRI, value);
 
-   /*
-* After a crash, we no longer service the interrupts and a pending
-* interrupt from previous kernel might still have ISR bit set.
-*
-* Most probably by now CPU has serviced that pending interrupt and
-* it might not have done the ack_APIC_irq() because it thought,
-* interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
-* does not clear the ISR bit and cpu thinks it has already serivced
-* the interrupt. Hence a vector might get locked. It was noticed
-* for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
-*/
-   do {
-   queued = 0;
-   for (i = APIC_ISR_NR - 1; i >= 0; i--)
-   queued |= apic_read(APIC_IRR + i*0x10);
-
-   for (i = APIC_ISR_NR - 1; i >= 0; i--) {
-   value = apic_read(APIC_ISR + i*0x10);
-   for (j = 31; j >= 0; j--) {
-   if (value & (1< 256) {
-   printk(KERN_ERR "LAPIC pending interrupts after %d 
EOI\n",
-  acked);
-   break;
-   }
-   if (queued) {
-   if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
-   ntsc = rdtsc();
-   max_loops = (cpu_khz << 10) - (ntsc - tsc);
-   } else
-   max_loops--;
-   }
-   } while (queued && max_loops > 0);
-   WARN_ON(max_loops <= 0);
+   apic_pending_intr_clear();
 
/*
 * Now that we are all set up, enable the APIC
-- 
2.14.3