[PARISC] Only write to memory in test_and_set_bit/test_and_clear_bit if we're
going to change the bit.
Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
diff --git a/include/asm-parisc/bitops.h b/include/asm-parisc/bitops.h
index 9005619..9577342 100644
--- a/include/asm-parisc/bitops.h
+++ b/include/asm-parisc/bitops.h
@@ -60,31 +60,37 @@
static __inline__ int test_and_set_bit(int nr, volatile unsigned long * addr)
{
unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
- unsigned long oldbit;
+ unsigned long old;
unsigned long flags;
+ int set;
addr += (nr >> SHIFT_PER_LONG);
_atomic_spin_lock_irqsave(addr, flags);
- oldbit = *addr;
- *addr = oldbit | mask;
+ old = *addr;
+ set = (old & mask) ? 1 : 0;
+ if (!set)
+ *addr = old | mask;
_atomic_spin_unlock_irqrestore(addr, flags);
- return (oldbit & mask) ? 1 : 0;
+ return set;
}
static __inline__ int test_and_clear_bit(int nr, volatile unsigned long * addr)
{
unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
- unsigned long oldbit;
+ unsigned long old;
unsigned long flags;
+ int set;
addr += (nr >> SHIFT_PER_LONG);
_atomic_spin_lock_irqsave(addr, flags);
- oldbit = *addr;
- *addr = oldbit & ~mask;
+ old = *addr;
+ set = (old & mask) ? 1 : 0;
+ if (set)
+ *addr = old & ~mask;
_atomic_spin_unlock_irqrestore(addr, flags);
- return (oldbit & mask) ? 1 : 0;
+ return set;
}
static __inline__ int test_and_change_bit(int nr, volatile unsigned long * addr)