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authorMatthew Wilcox <matthew@wil.cx>2006-12-14 09:00:25 -0700
committerKyle McMartin <kyle@athena.road.mcmartin.ca>2007-02-17 00:43:03 -0500
commitaf5917f0cd60715ed09874bb793d4f62ba692f47 (patch)
treef808220b3254089658d1c35c76096aadf989f38b /include/asm-parisc/bitops.h
parentd6ce8626dbc7d277d29b62e31c24ce777c60546b (diff)
[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>
Diffstat (limited to 'include/asm-parisc/bitops.h')
-rw-r--r--include/asm-parisc/bitops.h22
1 files changed, 14 insertions, 8 deletions
diff --git a/include/asm-parisc/bitops.h b/include/asm-parisc/bitops.h
index 900561922c4..9577342f21a 100644
--- a/include/asm-parisc/bitops.h
+++ b/include/asm-parisc/bitops.h
@@ -60,31 +60,37 @@ static __inline__ void change_bit(int nr, volatile unsigned long * addr)
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)