*/
typedef struct {
- volatile unsigned int lock;
+ volatile unsigned int slock;
#ifdef CONFIG_DEBUG_SPINLOCK
unsigned magic;
#endif
+#ifdef CONFIG_PREEMPT
+ unsigned int break_lock;
+#endif
} spinlock_t;
#define SPINLOCK_MAGIC 0xdead4ead
* We make no fairness assumptions. They have a cost.
*/
-#define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0)
+#define spin_is_locked(x) (*(volatile signed char *)(&(x)->slock) <= 0)
#define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
#define spin_lock_string \
* (except on PPro SMP or if we are using OOSTORE)
* (PPro errata 66, 92)
*/
-
+
#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
#define spin_unlock_string \
"movb $1,%0" \
- :"=m" (lock->lock) : : "memory"
+ :"=m" (lock->slock) : : "memory"
static inline void _raw_spin_unlock(spinlock_t *lock)
#define spin_unlock_string \
"xchgb %b0, %1" \
- :"=q" (oldval), "=m" (lock->lock) \
+ :"=q" (oldval), "=m" (lock->slock) \
:"0" (oldval) : "memory"
static inline void _raw_spin_unlock(spinlock_t *lock)
char oldval;
__asm__ __volatile__(
"xchgb %b0,%1"
- :"=q" (oldval), "=m" (lock->lock)
+ :"=q" (oldval), "=m" (lock->slock)
:"0" (0) : "memory");
return oldval > 0;
}
#endif
__asm__ __volatile__(
spin_lock_string
- :"=m" (lock->lock) : : "memory");
+ :"=m" (lock->slock) : : "memory");
}
static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
#endif
__asm__ __volatile__(
spin_lock_string_flags
- :"=m" (lock->lock) : "r" (flags) : "memory");
+ :"=m" (lock->slock) : "r" (flags) : "memory");
}
/*
#ifdef CONFIG_DEBUG_SPINLOCK
unsigned magic;
#endif
+#ifdef CONFIG_PREEMPT
+ unsigned int break_lock;
+#endif
} rwlock_t;
#define RWLOCK_MAGIC 0xdeaf1eed
#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0)
-#define rwlock_is_locked(x) ((x)->lock != RW_LOCK_BIAS)
+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define read_can_lock(x) ((int)(x)->lock > 0)
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+#define write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
/*
* On x86, we implement read-write locks as a 32-bit counter
#define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
#define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
+static inline int _raw_read_trylock(rwlock_t *lock)
+{
+ atomic_t *count = (atomic_t *)lock;
+ atomic_dec(count);
+ if (atomic_read(count) >= 0)
+ return 1;
+ atomic_inc(count);
+ return 0;
+}
+
static inline int _raw_write_trylock(rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;