[Adeos-main] [PATCH] janitorial: remove i8253_lock conversion

[Adeos-main] [PATCH] janitorial: remove i8253_lock conversion

[Jan Kiszka]

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Unless I'm utterly wrong, there are practically only two use cases
regarding the PIT: Either Linux has complete hold of it for clocksource
and/or clockevent usage, or the RT domain takes it over, also
completely. In both cases the RT domain does not need to use the
i8253_lock (see Xenomai). So let's remove the hunks that harden this
lock for no good (upcoming 2.6.24 would otherwise require even
_extended_ patching). Patch addresses i386, but this cleanup should be
applicable to x86_64 likewise.

Jan

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---
 arch/i386/kernel/i8253.c               |    2 +-
 arch/i386/mach-voyager/voyager_basic.c |    8 ++++----
 include/asm-i386/i8253.h               |    2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

Index: linux-2.6.23.1-xeno/arch/i386/kernel/i8253.c
===================================================================
--- linux-2.6.23.1-xeno.orig/arch/i386/kernel/i8253.c
+++ linux-2.6.23.1-xeno/arch/i386/kernel/i8253.c
@@ -16,7 +16,7 @@
 #include <asm/io.h>
 #include <asm/timer.h>
 
-IPIPE_DEFINE_SPINLOCK(i8253_lock);
+DEFINE_SPINLOCK(i8253_lock);
 EXPORT_SYMBOL(i8253_lock);
 
 /*
Index: linux-2.6.23.1-xeno/arch/i386/mach-voyager/voyager_basic.c
===================================================================
--- linux-2.6.23.1-xeno.orig/arch/i386/mach-voyager/voyager_basic.c
+++ linux-2.6.23.1-xeno/arch/i386/mach-voyager/voyager_basic.c
@@ -185,20 +185,20 @@ voyager_timer_interrupt(void)
 		 * pointy.  */
 		__u16 val;
 
-		spin_lock_irqsave(&i8253_lock);
+		spin_lock(&i8253_lock);
 		
 		outb_p(0x00, 0x43);
 		val = inb_p(0x40);
 		val |= inb(0x40) << 8;
-		spin_unlock_irqrestore(&i8253_lock);
+		spin_unlock(&i8253_lock);
 
 		if(val > LATCH) {
 			printk("\nVOYAGER: countdown timer value too high (%d), resetting\n\n", val);
-			spin_lock_irqsave(&i8253_lock);
+			spin_lock(&i8253_lock);
 			outb(0x34,0x43);
 			outb_p(LATCH & 0xff , 0x40);	/* LSB */
 			outb(LATCH >> 8 , 0x40);	/* MSB */
-			spin_unlock_irqrestore(&i8253_lock);
+			spin_unlock(&i8253_lock);
 		}
 	}
 #ifdef CONFIG_SMP
Index: linux-2.6.23.1-xeno/include/asm-i386/i8253.h
===================================================================
--- linux-2.6.23.1-xeno.orig/include/asm-i386/i8253.h
+++ linux-2.6.23.1-xeno/include/asm-i386/i8253.h
@@ -8,7 +8,7 @@
 #define PIT_CH0			0x40
 #define PIT_CH2			0x42
 
-extern ipipe_spinlock_t i8253_lock;
+extern spinlock_t i8253_lock;
 
 extern struct clock_event_device *global_clock_event;
 

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Re: [Adeos-main] [PATCH] janitorial: remove i8253_lock conversion

[Jan Kiszka]

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Jan Kiszka wrote:
> Unless I'm utterly wrong, there are practically only two use cases
> regarding the PIT: Either Linux has complete hold of it for clocksource
> and/or clockevent usage, or the RT domain takes it over, also
> completely. In both cases the RT domain does not need to use the
> i8253_lock (see Xenomai). So let's remove the hunks that harden this
> lock for no good (upcoming 2.6.24 would otherwise require even
> _extended_ patching). Patch addresses i386, but this cleanup should be
> applicable to x86_64 likewise.
> 
> Jan

PS: voyager hunk was uncompilable anyway.


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Re: [Adeos-main] [PATCH] janitorial: remove i8253_lock conversion

[Philippe Gerum]

Jan Kiszka wrote:
> Unless I'm utterly wrong, there are practically only two use cases
> regarding the PIT: Either Linux has complete hold of it for clocksource
> and/or clockevent usage, or the RT domain takes it over, also
> completely. In both cases the RT domain does not need to use the
> i8253_lock (see Xenomai).

Ack.

 So let's remove the hunks that harden this
> lock for no good (upcoming 2.6.24 would otherwise require even
> _extended_ patching). Patch addresses i386, but this cleanup should be
> applicable to x86_64 likewise.
>

Our x86_64 port relies on having APIC+TSC, so we don't even care about
the PIT anyway.

Will merge, thanks.

> Jan
> 


-- 
Philippe.

Re: [Adeos-main] [PATCH] janitorial: remove i8253_lock conversion

[Philippe Gerum]

Jan Kiszka wrote:
> Jan Kiszka wrote:
>> Unless I'm utterly wrong, there are practically only two use cases
>> regarding the PIT: Either Linux has complete hold of it for clocksource
>> and/or clockevent usage, or the RT domain takes it over, also
>> completely. In both cases the RT domain does not need to use the
>> i8253_lock (see Xenomai). So let's remove the hunks that harden this
>> lock for no good (upcoming 2.6.24 would otherwise require even
>> _extended_ patching). Patch addresses i386, but this cleanup should be
>> applicable to x86_64 likewise.
>>
>> Jan
> 
> PS: voyager hunk was uncompilable anyway.
> 

It's not the hunk, it's even the entire Voyager platform which we never
supported actually. This hunk was plainly useless indeed.

> 
> 
> ------------------------------------------------------------------------
> 
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-- 
Philippe.