[PATCH] x86: remove io_apic_sync

The patch below gets rid of io_apic_sync().

io_apic_sync() was introduced in 2.1.104 and it was originally done for
masking and unmasking as well.  Later the unmasking use got removed but the
masking use lingered around.  I dont think it was ever justified to do it
and clearly since the lack of io_apic_sync() didnt break some of the other
writes we do to the IO-APIC registers, it must be unnecessary in the
masking case too.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/io_apic.c

@@ -145,10 +145,7 @@ static void __modify_IO_APIC_irq (unsigned int irq, unsigned long enable, unsign
 /* mask = 1 */
 static void __mask_IO_APIC_irq (unsigned int irq)
 {
-	struct irq_pin_list *entry = irq_2_pin + irq;
 	__modify_IO_APIC_irq(irq, 0x00010000, 0);
-	/* Is it needed? Or do others need it too? */
-	io_apic_sync(entry->apic);
 }
 
 /* mask = 0 */

include/asm-i386/io_apic.h

@@ -188,15 +188,6 @@ static inline void io_apic_modify(unsigned int apic, unsigned int reg, unsigned
 	*(IO_APIC_BASE(apic)+4) = value;
 }
 
-/*
- * Synchronize the IO-APIC and the CPU by doing
- * a dummy read from the IO-APIC
- */
-static inline void io_apic_sync(unsigned int apic)
-{
-	(void) *(IO_APIC_BASE(apic)+4);
-}
-
 /* 1 if "noapic" boot option passed */
 extern int skip_ioapic_setup;