locking: Move spinlock function bodies to header file

Move spinlock function bodies to header file by creating a
static inline version of each variant. Use the inline version
on the out-of-line code.

This shouldn't make any difference besides that the spinlock
code can now be used to generate inlined spinlock code.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Horst Hartmann <horsth@linux.vnet.ibm.com>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <20090831124417.859022429@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 4be57ab..da76a06 100644 (file)
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -143,15 +143,6 @@ static inline void smp_mb__after_lock(void) { smp_mb(); }
  */
 #define spin_unlock_wait(lock) __raw_spin_unlock_wait(&(lock)->raw_lock)
 
-/*
- * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
- */
-#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-# include <linux/spinlock_api_smp.h>
-#else
-# include <linux/spinlock_api_up.h>
-#endif
-
 #ifdef CONFIG_DEBUG_SPINLOCK
  extern void _raw_spin_lock(spinlock_t *lock);
 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
@@ -380,4 +371,13 @@ extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
  */
 #define spin_can_lock(lock)    (!spin_is_locked(lock))
 
+/*
+ * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
+ */
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
+# include <linux/spinlock_api_smp.h>
+#else
+# include <linux/spinlock_api_up.h>
+#endif
+
 #endif /* __LINUX_SPINLOCK_H */

diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
index d79845d..6b108f5 100644 (file)
--- a/include/linux/spinlock_api_smp.h
+++ b/include/linux/spinlock_api_smp.h
@@ -60,4 +60,267 @@ void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
                                                        __releases(lock);
 
+static inline int __spin_trylock(spinlock_t *lock)
+{
+       preempt_disable();
+       if (_raw_spin_trylock(lock)) {
+               spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+               return 1;
+       }
+       preempt_enable();
+       return 0;
+}
+
+static inline int __read_trylock(rwlock_t *lock)
+{
+       preempt_disable();
+       if (_raw_read_trylock(lock)) {
+               rwlock_acquire_read(&lock->dep_map, 0, 1, _RET_IP_);
+               return 1;
+       }
+       preempt_enable();
+       return 0;
+}
+
+static inline int __write_trylock(rwlock_t *lock)
+{
+       preempt_disable();
+       if (_raw_write_trylock(lock)) {
+               rwlock_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+               return 1;
+       }
+       preempt_enable();
+       return 0;
+}
+
+/*
+ * If lockdep is enabled then we use the non-preemption spin-ops
+ * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
+ * not re-enabled during lock-acquire (which the preempt-spin-ops do):
+ */
+#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
+
+static inline void __read_lock(rwlock_t *lock)
+{
+       preempt_disable();
+       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+}
+
+static inline unsigned long __spin_lock_irqsave(spinlock_t *lock)
+{
+       unsigned long flags;
+
+       local_irq_save(flags);
+       preempt_disable();
+       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       /*
+        * On lockdep we dont want the hand-coded irq-enable of
+        * _raw_spin_lock_flags() code, because lockdep assumes
+        * that interrupts are not re-enabled during lock-acquire:
+        */
+#ifdef CONFIG_LOCKDEP
+       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+#else
+       _raw_spin_lock_flags(lock, &flags);
+#endif
+       return flags;
+}
+
+static inline void __spin_lock_irq(spinlock_t *lock)
+{
+       local_irq_disable();
+       preempt_disable();
+       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+}
+
+static inline void __spin_lock_bh(spinlock_t *lock)
+{
+       local_bh_disable();
+       preempt_disable();
+       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+}
+
+static inline unsigned long __read_lock_irqsave(rwlock_t *lock)
+{
+       unsigned long flags;
+
+       local_irq_save(flags);
+       preempt_disable();
+       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED_FLAGS(lock, _raw_read_trylock, _raw_read_lock,
+                            _raw_read_lock_flags, &flags);
+       return flags;
+}
+
+static inline void __read_lock_irq(rwlock_t *lock)
+{
+       local_irq_disable();
+       preempt_disable();
+       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+}
+
+static inline void __read_lock_bh(rwlock_t *lock)
+{
+       local_bh_disable();
+       preempt_disable();
+       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+}
+
+static inline unsigned long __write_lock_irqsave(rwlock_t *lock)
+{
+       unsigned long flags;
+
+       local_irq_save(flags);
+       preempt_disable();
+       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED_FLAGS(lock, _raw_write_trylock, _raw_write_lock,
+                            _raw_write_lock_flags, &flags);
+       return flags;
+}
+
+static inline void __write_lock_irq(rwlock_t *lock)
+{
+       local_irq_disable();
+       preempt_disable();
+       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+}
+
+static inline void __write_lock_bh(rwlock_t *lock)
+{
+       local_bh_disable();
+       preempt_disable();
+       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+}
+
+static inline void __spin_lock(spinlock_t *lock)
+{
+       preempt_disable();
+       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+}
+
+static inline void __write_lock(rwlock_t *lock)
+{
+       preempt_disable();
+       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+       LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+}
+
+#endif /* CONFIG_PREEMPT */
+
+static inline void __spin_unlock(spinlock_t *lock)
+{
+       spin_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_spin_unlock(lock);
+       preempt_enable();
+}
+
+static inline void __write_unlock(rwlock_t *lock)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_write_unlock(lock);
+       preempt_enable();
+}
+
+static inline void __read_unlock(rwlock_t *lock)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_read_unlock(lock);
+       preempt_enable();
+}
+
+static inline void __spin_unlock_irqrestore(spinlock_t *lock,
+                                           unsigned long flags)
+{
+       spin_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_spin_unlock(lock);
+       local_irq_restore(flags);
+       preempt_enable();
+}
+
+static inline void __spin_unlock_irq(spinlock_t *lock)
+{
+       spin_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_spin_unlock(lock);
+       local_irq_enable();
+       preempt_enable();
+}
+
+static inline void __spin_unlock_bh(spinlock_t *lock)
+{
+       spin_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_spin_unlock(lock);
+       preempt_enable_no_resched();
+       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+}
+
+static inline void __read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_read_unlock(lock);
+       local_irq_restore(flags);
+       preempt_enable();
+}
+
+static inline void __read_unlock_irq(rwlock_t *lock)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_read_unlock(lock);
+       local_irq_enable();
+       preempt_enable();
+}
+
+static inline void __read_unlock_bh(rwlock_t *lock)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_read_unlock(lock);
+       preempt_enable_no_resched();
+       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+}
+
+static inline void __write_unlock_irqrestore(rwlock_t *lock,
+                                            unsigned long flags)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_write_unlock(lock);
+       local_irq_restore(flags);
+       preempt_enable();
+}
+
+static inline void __write_unlock_irq(rwlock_t *lock)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_write_unlock(lock);
+       local_irq_enable();
+       preempt_enable();
+}
+
+static inline void __write_unlock_bh(rwlock_t *lock)
+{
+       rwlock_release(&lock->dep_map, 1, _RET_IP_);
+       _raw_write_unlock(lock);
+       preempt_enable_no_resched();
+       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+}
+
+static inline int __spin_trylock_bh(spinlock_t *lock)
+{
+       local_bh_disable();
+       preempt_disable();
+       if (_raw_spin_trylock(lock)) {
+               spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+               return 1;
+       }
+       preempt_enable_no_resched();
+       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+       return 0;
+}
+
 #endif /* __LINUX_SPINLOCK_API_SMP_H */

diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index 7932653..2c000f5 100644 (file)
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -23,40 +23,19 @@
 
 int __lockfunc _spin_trylock(spinlock_t *lock)
 {
-       preempt_disable();
-       if (_raw_spin_trylock(lock)) {
-               spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
-               return 1;
-       }
-       
-       preempt_enable();
-       return 0;
+       return __spin_trylock(lock);
 }
 EXPORT_SYMBOL(_spin_trylock);
 
 int __lockfunc _read_trylock(rwlock_t *lock)
 {
-       preempt_disable();
-       if (_raw_read_trylock(lock)) {
-               rwlock_acquire_read(&lock->dep_map, 0, 1, _RET_IP_);
-               return 1;
-       }
-
-       preempt_enable();
-       return 0;
+       return __read_trylock(lock);
 }
 EXPORT_SYMBOL(_read_trylock);
 
 int __lockfunc _write_trylock(rwlock_t *lock)
 {
-       preempt_disable();
-       if (_raw_write_trylock(lock)) {
-               rwlock_acquire(&lock->dep_map, 0, 1, _RET_IP_);
-               return 1;
-       }
-
-       preempt_enable();
-       return 0;
+       return __write_trylock(lock);
 }
 EXPORT_SYMBOL(_write_trylock);
 
@@ -69,129 +48,74 @@ EXPORT_SYMBOL(_write_trylock);
 
 void __lockfunc _read_lock(rwlock_t *lock)
 {
-       preempt_disable();
-       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+       __read_lock(lock);
 }
 EXPORT_SYMBOL(_read_lock);
 
 unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
 {
-       unsigned long flags;
-
-       local_irq_save(flags);
-       preempt_disable();
-       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       /*
-        * On lockdep we dont want the hand-coded irq-enable of
-        * _raw_spin_lock_flags() code, because lockdep assumes
-        * that interrupts are not re-enabled during lock-acquire:
-        */
-#ifdef CONFIG_LOCKDEP
-       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
-#else
-       _raw_spin_lock_flags(lock, &flags);
-#endif
-       return flags;
+       return __spin_lock_irqsave(lock);
 }
 EXPORT_SYMBOL(_spin_lock_irqsave);
 
 void __lockfunc _spin_lock_irq(spinlock_t *lock)
 {
-       local_irq_disable();
-       preempt_disable();
-       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+       __spin_lock_irq(lock);
 }
 EXPORT_SYMBOL(_spin_lock_irq);
 
 void __lockfunc _spin_lock_bh(spinlock_t *lock)
 {
-       local_bh_disable();
-       preempt_disable();
-       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+       __spin_lock_bh(lock);
 }
 EXPORT_SYMBOL(_spin_lock_bh);
 
 unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
 {
-       unsigned long flags;
-
-       local_irq_save(flags);
-       preempt_disable();
-       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED_FLAGS(lock, _raw_read_trylock, _raw_read_lock,
-                            _raw_read_lock_flags, &flags);
-       return flags;
+       return __read_lock_irqsave(lock);
 }
 EXPORT_SYMBOL(_read_lock_irqsave);
 
 void __lockfunc _read_lock_irq(rwlock_t *lock)
 {
-       local_irq_disable();
-       preempt_disable();
-       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+       __read_lock_irq(lock);
 }
 EXPORT_SYMBOL(_read_lock_irq);
 
 void __lockfunc _read_lock_bh(rwlock_t *lock)
 {
-       local_bh_disable();
-       preempt_disable();
-       rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+       __read_lock_bh(lock);
 }
 EXPORT_SYMBOL(_read_lock_bh);
 
 unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
 {
-       unsigned long flags;
-
-       local_irq_save(flags);
-       preempt_disable();
-       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED_FLAGS(lock, _raw_write_trylock, _raw_write_lock,
-                            _raw_write_lock_flags, &flags);
-       return flags;
+       return __write_lock_irqsave(lock);
 }
 EXPORT_SYMBOL(_write_lock_irqsave);
 
 void __lockfunc _write_lock_irq(rwlock_t *lock)
 {
-       local_irq_disable();
-       preempt_disable();
-       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+       __write_lock_irq(lock);
 }
 EXPORT_SYMBOL(_write_lock_irq);
 
 void __lockfunc _write_lock_bh(rwlock_t *lock)
 {
-       local_bh_disable();
-       preempt_disable();
-       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+       __write_lock_bh(lock);
 }
 EXPORT_SYMBOL(_write_lock_bh);
 
 void __lockfunc _spin_lock(spinlock_t *lock)
 {
-       preempt_disable();
-       spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+       __spin_lock(lock);
 }
-
 EXPORT_SYMBOL(_spin_lock);
 
 void __lockfunc _write_lock(rwlock_t *lock)
 {
-       preempt_disable();
-       rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-       LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+       __write_lock(lock);
 }
-
 EXPORT_SYMBOL(_write_lock);
 
 #else /* CONFIG_PREEMPT: */
@@ -320,121 +244,79 @@ EXPORT_SYMBOL(_spin_lock_nest_lock);
 
 void __lockfunc _spin_unlock(spinlock_t *lock)
 {
-       spin_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_spin_unlock(lock);
-       preempt_enable();
+       __spin_unlock(lock);
 }
 EXPORT_SYMBOL(_spin_unlock);
 
 void __lockfunc _write_unlock(rwlock_t *lock)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_write_unlock(lock);
-       preempt_enable();
+       __write_unlock(lock);
 }
 EXPORT_SYMBOL(_write_unlock);
 
 void __lockfunc _read_unlock(rwlock_t *lock)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_read_unlock(lock);
-       preempt_enable();
+       __read_unlock(lock);
 }
 EXPORT_SYMBOL(_read_unlock);
 
 void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 {
-       spin_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_spin_unlock(lock);
-       local_irq_restore(flags);
-       preempt_enable();
+       __spin_unlock_irqrestore(lock, flags);
 }
 EXPORT_SYMBOL(_spin_unlock_irqrestore);
 
 void __lockfunc _spin_unlock_irq(spinlock_t *lock)
 {
-       spin_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_spin_unlock(lock);
-       local_irq_enable();
-       preempt_enable();
+       __spin_unlock_irq(lock);
 }
 EXPORT_SYMBOL(_spin_unlock_irq);
 
 void __lockfunc _spin_unlock_bh(spinlock_t *lock)
 {
-       spin_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_spin_unlock(lock);
-       preempt_enable_no_resched();
-       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+       __spin_unlock_bh(lock);
 }
 EXPORT_SYMBOL(_spin_unlock_bh);
 
 void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_read_unlock(lock);
-       local_irq_restore(flags);
-       preempt_enable();
+       __read_unlock_irqrestore(lock, flags);
 }
 EXPORT_SYMBOL(_read_unlock_irqrestore);
 
 void __lockfunc _read_unlock_irq(rwlock_t *lock)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_read_unlock(lock);
-       local_irq_enable();
-       preempt_enable();
+       __read_unlock_irq(lock);
 }
 EXPORT_SYMBOL(_read_unlock_irq);
 
 void __lockfunc _read_unlock_bh(rwlock_t *lock)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_read_unlock(lock);
-       preempt_enable_no_resched();
-       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+       __read_unlock_bh(lock);
 }
 EXPORT_SYMBOL(_read_unlock_bh);
 
 void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_write_unlock(lock);
-       local_irq_restore(flags);
-       preempt_enable();
+       __write_unlock_irqrestore(lock, flags);
 }
 EXPORT_SYMBOL(_write_unlock_irqrestore);
 
 void __lockfunc _write_unlock_irq(rwlock_t *lock)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_write_unlock(lock);
-       local_irq_enable();
-       preempt_enable();
+       __write_unlock_irq(lock);
 }
 EXPORT_SYMBOL(_write_unlock_irq);
 
 void __lockfunc _write_unlock_bh(rwlock_t *lock)
 {
-       rwlock_release(&lock->dep_map, 1, _RET_IP_);
-       _raw_write_unlock(lock);
-       preempt_enable_no_resched();
-       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
+       __write_unlock_bh(lock);
 }
 EXPORT_SYMBOL(_write_unlock_bh);
 
 int __lockfunc _spin_trylock_bh(spinlock_t *lock)
 {
-       local_bh_disable();
-       preempt_disable();
-       if (_raw_spin_trylock(lock)) {
-               spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
-               return 1;
-       }
-
-       preempt_enable_no_resched();
-       local_bh_enable_ip((unsigned long)__builtin_return_address(0));
-       return 0;
+       return __spin_trylock_bh(lock);
 }
 EXPORT_SYMBOL(_spin_trylock_bh);