The patch titled
rwsem: implement rwsem_is_contended()
has been added to the -mm tree. Its filename is
rwsem-implement-rwsem_is_contended.patch
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------------------------------------------------------
Subject: rwsem: implement rwsem_is_contended()
From: Michel Lespinasse <walken@xxxxxxxxxx>
Trivial implementations for rwsem_is_contended()
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(+)
diff -puN arch/alpha/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/alpha/include/asm/rwsem.h
--- a/arch/alpha/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/alpha/include/asm/rwsem.h
@@ -255,5 +255,10 @@ static inline int rwsem_is_locked(struct
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 -puN arch/ia64/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/ia64/include/asm/rwsem.h
--- a/arch/ia64/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/ia64/include/asm/rwsem.h
@@ -179,4 +179,9 @@ static inline int rwsem_is_locked(struct
return (sem->count != 0);
}
+static inline int rwsem_is_contended(struct rw_semaphore *sem)
+{
+ return (sem->count < 0);
+}
+
#endif /* _ASM_IA64_RWSEM_H */
diff -puN arch/powerpc/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/powerpc/include/asm/rwsem.h
--- a/arch/powerpc/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/powerpc/include/asm/rwsem.h
@@ -179,5 +179,10 @@ static inline int rwsem_is_locked(struct
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 -puN arch/s390/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/s390/include/asm/rwsem.h
--- a/arch/s390/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/s390/include/asm/rwsem.h
@@ -382,5 +382,10 @@ static inline int rwsem_is_locked(struct
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 -puN arch/sh/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/sh/include/asm/rwsem.h
--- a/arch/sh/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/sh/include/asm/rwsem.h
@@ -184,5 +184,10 @@ static inline int rwsem_is_locked(struct
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 -puN arch/sparc/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/sparc/include/asm/rwsem.h
--- a/arch/sparc/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/sparc/include/asm/rwsem.h
@@ -165,6 +165,11 @@ static inline int rwsem_is_locked(struct
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 -puN arch/x86/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/x86/include/asm/rwsem.h
--- a/arch/x86/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/x86/include/asm/rwsem.h
@@ -275,5 +275,10 @@ static inline int rwsem_is_locked(struct
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 -puN arch/xtensa/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended arch/xtensa/include/asm/rwsem.h
--- a/arch/xtensa/include/asm/rwsem.h~rwsem-implement-rwsem_is_contended
+++ a/arch/xtensa/include/asm/rwsem.h
@@ -165,4 +165,9 @@ static inline int rwsem_is_locked(struct
return (sem->count != 0);
}
+static inline int rwsem_is_contended(struct rw_semaphore *sem)
+{
+ return (sem->count < 0);
+}
+
#endif /* _XTENSA_RWSEM_H */
diff -puN include/linux/rwsem-spinlock.h~rwsem-implement-rwsem_is_contended include/linux/rwsem-spinlock.h
--- a/include/linux/rwsem-spinlock.h~rwsem-implement-rwsem_is_contended
+++ a/include/linux/rwsem-spinlock.h
@@ -69,6 +69,7 @@ extern void __up_read(struct rw_semaphor
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 -puN lib/rwsem-spinlock.c~rwsem-implement-rwsem_is_contended lib/rwsem-spinlock.c
--- a/lib/rwsem-spinlock.c~rwsem-implement-rwsem_is_contended
+++ a/lib/rwsem-spinlock.c
@@ -30,6 +30,18 @@ int rwsem_is_locked(struct rw_semaphore
}
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
*/
_
Patches currently in -mm which might be from walken@xxxxxxxxxx are
do_wp_page-remove-the-reuse-flag.patch
do_wp_page-clarify-dirty_page-handling.patch
mlock-avoid-dirtying-pages-and-triggering-writeback.patch
mlock-only-hold-mmap_sem-in-shared-mode-when-faulting-in-pages.patch
mm-add-foll_mlock-follow_page-flag.patch
mm-move-vm_locked-check-to-__mlock_vma_pages_range.patch
rwsem-implement-rwsem_is_contended.patch
mlock-do-not-hold-mmap_sem-for-extended-periods-of-time.patch
x86-rwsem-more-precise-rwsem_is_contended-implementation.patch
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