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Date: Tue, 24 Feb 2009 22:58:36 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: lkml <linux-kernel@...r.kernel.org>
Cc: David Howells <dhowells@...hat.com>,
Matthew Wilcox <matthew@....cx>, Ingo Molnar <mingo@...e.hu>,
Nick Piggin <nickpiggin@...oo.com.au>,
Christoph Hellwig <hch@...radead.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC][PATCH] rwsem: rwsem_is_{read,write}_locked
Christoph requested an extended is_locked interface for rwsems. I think
the below ought to do, then again, I might have missed something.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
arch/alpha/include/asm/rwsem.h | 5 -----
arch/ia64/include/asm/rwsem.h | 5 -----
arch/powerpc/include/asm/rwsem.h | 5 -----
arch/s390/include/asm/rwsem.h | 5 -----
arch/sh/include/asm/rwsem.h | 5 -----
arch/sparc/include/asm/rwsem.h | 5 -----
arch/x86/include/asm/rwsem.h | 5 -----
arch/xtensa/include/asm/rwsem.h | 5 -----
include/linux/rwsem-spinlock.h | 5 +++++
include/linux/rwsem.h | 16 ++++++++++++++++
10 files changed, 21 insertions(+), 40 deletions(-)
diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h
index 1570c0b..fdc8dc3 100644
--- a/arch/alpha/include/asm/rwsem.h
+++ b/arch/alpha/include/asm/rwsem.h
@@ -250,10 +250,5 @@ static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem)
#endif
}
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
-{
- return (sem->count != 0);
-}
-
#endif /* __KERNEL__ */
#endif /* _ALPHA_RWSEM_H */
diff --git a/arch/ia64/include/asm/rwsem.h b/arch/ia64/include/asm/rwsem.h
index fbee74b..4b4bfa5 100644
--- a/arch/ia64/include/asm/rwsem.h
+++ b/arch/ia64/include/asm/rwsem.h
@@ -174,9 +174,4 @@ __downgrade_write (struct rw_semaphore *sem)
#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 */
diff --git a/arch/powerpc/include/asm/rwsem.h b/arch/powerpc/include/asm/rwsem.h
index 24cd928..27d1acf 100644
--- a/arch/powerpc/include/asm/rwsem.h
+++ b/arch/powerpc/include/asm/rwsem.h
@@ -164,10 +164,5 @@ static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
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_POWERPC_RWSEM_H */
diff --git a/arch/s390/include/asm/rwsem.h b/arch/s390/include/asm/rwsem.h
index 9d2a179..d9ab6c6 100644
--- a/arch/s390/include/asm/rwsem.h
+++ b/arch/s390/include/asm/rwsem.h
@@ -378,10 +378,5 @@ static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
return new;
}
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
-{
- return (sem->count != 0);
-}
-
#endif /* __KERNEL__ */
#endif /* _S390_RWSEM_H */
diff --git a/arch/sh/include/asm/rwsem.h b/arch/sh/include/asm/rwsem.h
index 1987f3e..5aded81 100644
--- a/arch/sh/include/asm/rwsem.h
+++ b/arch/sh/include/asm/rwsem.h
@@ -179,10 +179,5 @@ static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
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 */
diff --git a/arch/sparc/include/asm/rwsem.h b/arch/sparc/include/asm/rwsem.h
index 1dc129a..a3f43c9 100644
--- a/arch/sparc/include/asm/rwsem.h
+++ b/arch/sparc/include/asm/rwsem.h
@@ -74,11 +74,6 @@ static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
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 */
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index ca7517d..a22dc3b 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -256,10 +256,5 @@ static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
return tmp + delta;
}
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
-{
- return (sem->count != 0);
-}
-
#endif /* __KERNEL__ */
#endif /* _ASM_X86_RWSEM_H */
diff --git a/arch/xtensa/include/asm/rwsem.h b/arch/xtensa/include/asm/rwsem.h
index e39edf5..e960d99 100644
--- a/arch/xtensa/include/asm/rwsem.h
+++ b/arch/xtensa/include/asm/rwsem.h
@@ -160,9 +160,4 @@ static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
return atomic_add_return(delta, (atomic_t *)(&sem->count));
}
-static inline int rwsem_is_locked(struct rw_semaphore *sem)
-{
- return (sem->count != 0);
-}
-
#endif /* _XTENSA_RWSEM_H */
diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h
index 6c3c0f6..00c76f7 100644
--- a/include/linux/rwsem-spinlock.h
+++ b/include/linux/rwsem-spinlock.h
@@ -74,5 +74,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->activity != 0);
}
+static inline int rwsem_is_write_locked(struct rw_semaphore *sem)
+{
+ return (sem->activity < 0);
+}
+
#endif /* __KERNEL__ */
#endif /* _LINUX_RWSEM_SPINLOCK_H */
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index efd348f..9d7531b 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -20,8 +20,24 @@ struct rw_semaphore;
#include <linux/rwsem-spinlock.h> /* use a generic implementation */
#else
#include <asm/rwsem.h> /* use an arch-specific implementation */
+
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+ return (sem->count != 0);
+}
+
+static inline int rwsem_is_write_locked(struct rw_semaphore *sem)
+{
+ return (sem->count & RWSEM_ACTIVE_MASK) == RWSEM_ACTIVE_MASK;
+}
+
#endif
+static inline int rwsem_is_read_locked(struct rw_semaphore *sem)
+{
+ return rwsem_is_locked(sem) && !rwsem_is_write_locked(sem);
+}
+
/*
* lock for reading
*/
--
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