bit_spin_lock: use lock bitops

Convert bit_spin_lock to new locking bitops.  Slub can use the non-atomic
store version to clear (Christoph?)

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
index 6b20af0..7113a32 100644 (file)
--- a/include/linux/bit_spinlock.h
+++ b/include/linux/bit_spinlock.h
@@ -18,7 +18,7 @@ static inline void bit_spin_lock(int bitnum, unsigned long *addr)
         */
        preempt_disable();
 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-       while (test_and_set_bit(bitnum, addr)) {
+       while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
                while (test_bit(bitnum, addr)) {
                        preempt_enable();
                        cpu_relax();
@@ -36,7 +36,7 @@ static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
 {
        preempt_disable();
 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-       if (test_and_set_bit(bitnum, addr)) {
+       if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
                preempt_enable();
                return 0;
        }
@@ -50,10 +50,28 @@ static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
  */
 static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
 {
+#ifdef CONFIG_DEBUG_SPINLOCK
+       BUG_ON(!test_bit(bitnum, addr));
+#endif
 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
+       clear_bit_unlock(bitnum, addr);
+#endif
+       preempt_enable();
+       __release(bitlock);
+}
+
+/*
+ *  bit-based spin_unlock()
+ *  non-atomic version, which can be used eg. if the bit lock itself is
+ *  protecting the rest of the flags in the word.
+ */
+static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
        BUG_ON(!test_bit(bitnum, addr));
-       smp_mb__before_clear_bit();
-       clear_bit(bitnum, addr);
+#endif
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
+       __clear_bit_unlock(bitnum, addr);
 #endif
        preempt_enable();
        __release(bitlock);