[PATCH] add sem_is_read/write_locked()

Add sem_is_read/write_locked functions to the read/write semaphores, along the
same lines of the *_is_locked spinlock functions. The swap token tuning patch
uses sem_is_read_locked; sem_is_write_locked is added for completeness.

Signed-off-by: Rik van Riel <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/asm-alpha/rwsem.h

···
 #endif
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _ALPHA_RWSEM_H */

include/asm-i386/rwsem.h

···
 	return tmp+delta;
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _I386_RWSEM_H */

include/asm-ia64/rwsem.h

···
 #define rwsem_atomic_add(delta, sem)	atomic64_add(delta, (atomic64_t *)(&(sem)->count))
 #define rwsem_atomic_update(delta, sem)	atomic64_add_return(delta, (atomic64_t *)(&(sem)->count))
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* _ASM_IA64_RWSEM_H */

include/asm-ppc/rwsem.h

···
 	return atomic_add_return(delta, (atomic_t *)(&sem->count));
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _PPC_RWSEM_XADD_H */

include/asm-ppc64/rwsem.h

···
 	return atomic_add_return(delta, (atomic_t *)(&sem->count));
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _PPC_RWSEM_XADD_H */

include/asm-s390/rwsem.h

···
 	return new;
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _S390_RWSEM_H */

include/asm-sh/rwsem.h

···
 	return atomic_add_return(delta, (atomic_t *)(&sem->count));
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _ASM_SH_RWSEM_H */

include/asm-sparc64/rwsem.h

···
 	atomic_add(delta, (atomic_t *)(&sem->count));
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* _SPARC64_RWSEM_H */

include/asm-x86_64/rwsem.h

···
 	return tmp+delta;
 }
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->count != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _X8664_RWSEM_H */

include/linux/rwsem-spinlock.h

···
 extern void FASTCALL(__up_write(struct rw_semaphore *sem));
 extern void FASTCALL(__downgrade_write(struct rw_semaphore *sem));
 
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+	return (sem->activity != 0);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_RWSEM_SPINLOCK_H */