#define __ASM_SPINLOCK_H
#include <asm/system.h>
+#include <asm/processor.h>
+#include <asm/spinlock_types.h>
-/* Note that PA-RISC has to use `1' to mean unlocked and `0' to mean locked
- * since it only has load-and-zero. Moreover, at least on some PA processors,
- * the semaphore address has to be 16-byte aligned.
- */
-
-#ifndef CONFIG_DEBUG_SPINLOCK
-
-#define __SPIN_LOCK_UNLOCKED { { 1, 1, 1, 1 } }
-#undef SPIN_LOCK_UNLOCKED
-#define SPIN_LOCK_UNLOCKED (spinlock_t) __SPIN_LOCK_UNLOCKED
-
-#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
-
-static inline int spin_is_locked(spinlock_t *x)
+static inline int __raw_spin_is_locked(raw_spinlock_t *x)
{
volatile unsigned int *a = __ldcw_align(x);
return *a == 0;
}
-#define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+#define __raw_spin_lock(lock) __raw_spin_lock_flags(lock, 0)
+#define __raw_spin_unlock_wait(x) \
+ do { cpu_relax(); } while (__raw_spin_is_locked(x))
-static inline void _raw_spin_lock(spinlock_t *x)
+static inline void __raw_spin_lock_flags(raw_spinlock_t *x,
+ unsigned long flags)
{
volatile unsigned int *a;
mb();
a = __ldcw_align(x);
while (__ldcw(a) == 0)
- while (*a == 0);
+ while (*a == 0)
+ if (flags & PSW_SM_I) {
+ local_irq_enable();
+ cpu_relax();
+ local_irq_disable();
+ } else
+ cpu_relax();
mb();
}
-static inline void _raw_spin_unlock(spinlock_t *x)
+static inline void __raw_spin_unlock(raw_spinlock_t *x)
{
volatile unsigned int *a;
mb();
mb();
}
-static inline int _raw_spin_trylock(spinlock_t *x)
+static inline int __raw_spin_trylock(raw_spinlock_t *x)
{
volatile unsigned int *a;
int ret;
return ret;
}
-
-#define spin_lock_own(LOCK, LOCATION) ((void)0)
-
-#else /* !(CONFIG_DEBUG_SPINLOCK) */
-
-#define SPINLOCK_MAGIC 0x1D244B3C
-
-#define __SPIN_LOCK_UNLOCKED { { 1, 1, 1, 1 }, SPINLOCK_MAGIC, 10, __FILE__ , NULL, 0, -1, NULL, NULL }
-#undef SPIN_LOCK_UNLOCKED
-#define SPIN_LOCK_UNLOCKED (spinlock_t) __SPIN_LOCK_UNLOCKED
-
-#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
-
-#define CHECK_LOCK(x) \
- do { \
- if (unlikely((x)->magic != SPINLOCK_MAGIC)) { \
- printk(KERN_ERR "%s:%d: spin_is_locked" \
- " on uninitialized spinlock %p.\n", \
- __FILE__, __LINE__, (x)); \
- } \
- } while(0)
-
-#define spin_is_locked(x) \
- ({ \
- CHECK_LOCK(x); \
- volatile unsigned int *a = __ldcw_align(x); \
- if (unlikely((*a == 0) && (x)->babble)) { \
- (x)->babble--; \
- printk("KERN_WARNING \
- %s:%d: spin_is_locked(%s/%p) already" \
- " locked by %s:%d in %s at %p(%d)\n", \
- __FILE__,__LINE__, (x)->module, (x), \
- (x)->bfile, (x)->bline, (x)->task->comm,\
- (x)->previous, (x)->oncpu); \
- } \
- *a == 0; \
- })
-
-#define spin_unlock_wait(x) \
- do { \
- CHECK_LOCK(x); \
- volatile unsigned int *a = __ldcw_align(x); \
- if (unlikely((*a == 0) && (x)->babble)) { \
- (x)->babble--; \
- printk("KERN_WARNING \
- %s:%d: spin_unlock_wait(%s/%p)" \
- " owned by %s:%d in %s at %p(%d)\n", \
- __FILE__,__LINE__, (x)->module, (x), \
- (x)->bfile, (x)->bline, (x)->task->comm,\
- (x)->previous, (x)->oncpu); \
- } \
- barrier(); \
- } while (*((volatile unsigned char *)(__ldcw_align(x))) == 0)
-
-extern void _dbg_spin_lock(spinlock_t *lock, const char *base_file, int line_no);
-extern void _dbg_spin_unlock(spinlock_t *lock, const char *, int);
-extern int _dbg_spin_trylock(spinlock_t * lock, const char *, int);
-
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
-
-#define _raw_spin_unlock(lock) _dbg_spin_unlock(lock, __FILE__, __LINE__)
-#define _raw_spin_lock(lock) _dbg_spin_lock(lock, __FILE__, __LINE__)
-#define _raw_spin_trylock(lock) _dbg_spin_trylock(lock, __FILE__, __LINE__)
-
-/* just in case we need it */
-#define spin_lock_own(LOCK, LOCATION) \
-do { \
- volatile unsigned int *a = __ldcw_align(LOCK); \
- if (!((*a == 0) && ((LOCK)->oncpu == smp_processor_id()))) \
- printk("KERN_WARNING \
- %s: called on %d from %p but lock %s on %d\n", \
- LOCATION, smp_processor_id(), \
- __builtin_return_address(0), \
- (*a == 0) ? "taken" : "freed", (LOCK)->on_cpu); \
-} while (0)
-
-#endif /* !(CONFIG_DEBUG_SPINLOCK) */
/*
- * Read-write spinlocks, allowing multiple readers
- * but only one writer.
+ * Read-write spinlocks, allowing multiple readers but only one writer.
+ * Linux rwlocks are unfair to writers; they can be starved for an indefinite
+ * time by readers. With care, they can also be taken in interrupt context.
+ *
+ * In the PA-RISC implementation, we have a spinlock and a counter.
+ * Readers use the lock to serialise their access to the counter (which
+ * records how many readers currently hold the lock).
+ * Writers hold the spinlock, preventing any readers or other writers from
+ * grabbing the rwlock.
*/
-typedef struct {
- spinlock_t lock;
- volatile int counter;
-#ifdef CONFIG_PREEMPT
- unsigned int break_lock;
-#endif
-} rwlock_t;
-
-#define RW_LOCK_UNLOCKED (rwlock_t) { __SPIN_LOCK_UNLOCKED, 0 }
-
-#define rwlock_init(lp) do { *(lp) = RW_LOCK_UNLOCKED; } while (0)
-
-#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
-/* read_lock, read_unlock are pretty straightforward. Of course it somehow
- * sucks we end up saving/restoring flags twice for read_lock_irqsave aso. */
-
-#ifdef CONFIG_DEBUG_RWLOCK
-extern void _dbg_read_lock(rwlock_t * rw, const char *bfile, int bline);
-#define _raw_read_lock(rw) _dbg_read_lock(rw, __FILE__, __LINE__)
-#else
-static __inline__ void _raw_read_lock(rwlock_t *rw)
+/* Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to grab the same read lock */
+static __inline__ void __raw_read_lock(raw_rwlock_t *rw)
{
unsigned long flags;
local_irq_save(flags);
- _raw_spin_lock(&rw->lock);
-
+ __raw_spin_lock_flags(&rw->lock, flags);
rw->counter++;
-
- _raw_spin_unlock(&rw->lock);
+ __raw_spin_unlock(&rw->lock);
local_irq_restore(flags);
}
-#endif /* CONFIG_DEBUG_RWLOCK */
-static __inline__ void _raw_read_unlock(rwlock_t *rw)
+/* Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to grab the same read lock */
+static __inline__ void __raw_read_unlock(raw_rwlock_t *rw)
{
unsigned long flags;
local_irq_save(flags);
- _raw_spin_lock(&rw->lock);
-
+ __raw_spin_lock_flags(&rw->lock, flags);
rw->counter--;
-
- _raw_spin_unlock(&rw->lock);
+ __raw_spin_unlock(&rw->lock);
local_irq_restore(flags);
}
-/* write_lock is less trivial. We optimistically grab the lock and check
- * if we surprised any readers. If so we release the lock and wait till
- * they're all gone before trying again
- *
- * Also note that we don't use the _irqsave / _irqrestore suffixes here.
- * If we're called with interrupts enabled and we've got readers (or other
- * writers) in interrupt handlers someone fucked up and we'd dead-lock
- * sooner or later anyway. prumpf */
+/* Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to grab the same read lock */
+static __inline__ int __raw_read_trylock(raw_rwlock_t *rw)
+{
+ unsigned long flags;
+ retry:
+ local_irq_save(flags);
+ if (__raw_spin_trylock(&rw->lock)) {
+ rw->counter++;
+ __raw_spin_unlock(&rw->lock);
+ local_irq_restore(flags);
+ return 1;
+ }
+
+ local_irq_restore(flags);
+ /* If write-locked, we fail to acquire the lock */
+ if (rw->counter < 0)
+ return 0;
-#ifdef CONFIG_DEBUG_RWLOCK
-extern void _dbg_write_lock(rwlock_t * rw, const char *bfile, int bline);
-#define _raw_write_lock(rw) _dbg_write_lock(rw, __FILE__, __LINE__)
-#else
-static __inline__ void _raw_write_lock(rwlock_t *rw)
+ /* Wait until we have a realistic chance at the lock */
+ while (__raw_spin_is_locked(&rw->lock) && rw->counter >= 0)
+ cpu_relax();
+
+ goto retry;
+}
+
+/* Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to read_trylock() this lock */
+static __inline__ void __raw_write_lock(raw_rwlock_t *rw)
{
+ unsigned long flags;
retry:
- _raw_spin_lock(&rw->lock);
+ local_irq_save(flags);
+ __raw_spin_lock_flags(&rw->lock, flags);
- if(rw->counter != 0) {
- /* this basically never happens */
- _raw_spin_unlock(&rw->lock);
+ if (rw->counter != 0) {
+ __raw_spin_unlock(&rw->lock);
+ local_irq_restore(flags);
- while(rw->counter != 0);
+ while (rw->counter != 0)
+ cpu_relax();
goto retry;
}
- /* got it. now leave without unlocking */
- rw->counter = -1; /* remember we are locked */
+ rw->counter = -1; /* mark as write-locked */
+ mb();
+ local_irq_restore(flags);
}
-#endif /* CONFIG_DEBUG_RWLOCK */
-/* write_unlock is absolutely trivial - we don't have to wait for anything */
-
-static __inline__ void _raw_write_unlock(rwlock_t *rw)
+static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
{
rw->counter = 0;
- _raw_spin_unlock(&rw->lock);
+ __raw_spin_unlock(&rw->lock);
}
-#ifdef CONFIG_DEBUG_RWLOCK
-extern int _dbg_write_trylock(rwlock_t * rw, const char *bfile, int bline);
-#define _raw_write_trylock(rw) _dbg_write_trylock(rw, __FILE__, __LINE__)
-#else
-static __inline__ int _raw_write_trylock(rwlock_t *rw)
+/* Note that we have to ensure interrupts are disabled in case we're
+ * interrupted by some other code that wants to read_trylock() this lock */
+static __inline__ int __raw_write_trylock(raw_rwlock_t *rw)
{
- _raw_spin_lock(&rw->lock);
- if (rw->counter != 0) {
- /* this basically never happens */
- _raw_spin_unlock(&rw->lock);
+ unsigned long flags;
+ int result = 0;
- return 0;
+ local_irq_save(flags);
+ if (__raw_spin_trylock(&rw->lock)) {
+ if (rw->counter == 0) {
+ rw->counter = -1;
+ result = 1;
+ } else {
+ /* Read-locked. Oh well. */
+ __raw_spin_unlock(&rw->lock);
+ }
}
+ local_irq_restore(flags);
- /* got it. now leave without unlocking */
- rw->counter = -1; /* remember we are locked */
- return 1;
+ return result;
}
-#endif /* CONFIG_DEBUG_RWLOCK */
-static __inline__ int is_read_locked(rwlock_t *rw)
+/*
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static __inline__ int __raw_read_can_lock(raw_rwlock_t *rw)
{
- return rw->counter > 0;
+ return rw->counter >= 0;
}
-static __inline__ int is_write_locked(rwlock_t *rw)
+/*
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static __inline__ int __raw_write_can_lock(raw_rwlock_t *rw)
{
- return rw->counter < 0;
+ return !rw->counter;
}
+#define _raw_spin_relax(lock) cpu_relax()
+#define _raw_read_relax(lock) cpu_relax()
+#define _raw_write_relax(lock) cpu_relax()
+
#endif /* __ASM_SPINLOCK_H */
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