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Message-Id: <1291335412-16231-5-git-send-email-walken@google.com>
Date: Thu, 2 Dec 2010 16:16:50 -0800
From: Michel Lespinasse <walken@...gle.com>
To: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
Rik van Riel <riel@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Nick Piggin <npiggin@...nel.dk>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4/6] rwsem: implement rwsem_is_contended()
Trivial implementations for rwsem_is_contended()
Signed-off-by: Michel Lespinasse <walken@...gle.com>
---
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 | 1 +
lib/rwsem-spinlock.c | 12 ++++++++++++
10 files changed, 53 insertions(+), 0 deletions(-)
diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h
index 1570c0b..6183eec 100644
--- a/arch/alpha/include/asm/rwsem.h
+++ b/arch/alpha/include/asm/rwsem.h
@@ -255,5 +255,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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 215d545..e965b7a 100644
--- a/arch/ia64/include/asm/rwsem.h
+++ b/arch/ia64/include/asm/rwsem.h
@@ -179,4 +179,9 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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 8447d89..69f5d13 100644
--- a/arch/powerpc/include/asm/rwsem.h
+++ b/arch/powerpc/include/asm/rwsem.h
@@ -179,5 +179,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return sem->count != 0;
}
+static inline int rwsem_is_contended(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 423fdda..7d36f68 100644
--- a/arch/s390/include/asm/rwsem.h
+++ b/arch/s390/include/asm/rwsem.h
@@ -382,5 +382,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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 06e2251..1f59516 100644
--- a/arch/sh/include/asm/rwsem.h
+++ b/arch/sh/include/asm/rwsem.h
@@ -184,5 +184,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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 a2b4302..88242e6 100644
--- a/arch/sparc/include/asm/rwsem.h
+++ b/arch/sparc/include/asm/rwsem.h
@@ -165,6 +165,11 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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 d1e41b0..a35521e 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -275,5 +275,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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..6c658cb 100644
--- a/arch/xtensa/include/asm/rwsem.h
+++ b/arch/xtensa/include/asm/rwsem.h
@@ -165,4 +165,9 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
return (sem->count != 0);
}
+static inline int rwsem_is_contended(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 bdfcc25..430de5b 100644
--- a/include/linux/rwsem-spinlock.h
+++ b/include/linux/rwsem-spinlock.h
@@ -69,6 +69,7 @@ extern void __up_read(struct rw_semaphore *sem);
extern void __up_write(struct rw_semaphore *sem);
extern void __downgrade_write(struct rw_semaphore *sem);
extern int rwsem_is_locked(struct rw_semaphore *sem);
+extern int rwsem_is_contended(struct rw_semaphore *sem);
#endif /* __KERNEL__ */
#endif /* _LINUX_RWSEM_SPINLOCK_H */
diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c
index ffc9fc7..783753d 100644
--- a/lib/rwsem-spinlock.c
+++ b/lib/rwsem-spinlock.c
@@ -30,6 +30,18 @@ int rwsem_is_locked(struct rw_semaphore *sem)
}
EXPORT_SYMBOL(rwsem_is_locked);
+int rwsem_is_contended(struct rw_semaphore *sem)
+{
+ int ret = 0;
+ unsigned long flags;
+
+ if (spin_trylock_irqsave(&sem->wait_lock, flags)) {
+ ret = !list_empty(&sem->wait_list);
+ spin_unlock_irqrestore(&sem->wait_lock, flags);
+ }
+ return ret;
+}
+
/*
* initialise the semaphore
*/
--
1.7.3.1
--
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