From af5917f0cd60715ed09874bb793d4f62ba692f47 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Thu, 14 Dec 2006 09:00:25 -0700 Subject: [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 Signed-off-by: Kyle McMartin --- include/asm-parisc/bitops.h | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'include/asm-parisc') 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__ 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) -- cgit v1.1