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authorShaohua Li <shli@kernel.org>2012-10-08 16:32:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:46 +0900
commite79bee24fd6134f90af4228cfebd010136d67631 (patch)
treeecc678106bbf4672becca8f798aaf94276eaa2c4
parent435b405c06119d93333738172b8060b0ed12af41 (diff)
atomic: implement generic atomic_dec_if_positive()
The x86 implementation of atomic_dec_if_positive is quite generic, so make it available to all architectures. This is needed for "swap: add a simple detector for inappropriate swapin readahead". [akpm@linux-foundation.org: do the "#define foo foo" trick in the conventional manner] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michal Simek <monstr@monstr.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/microblaze/include/asm/atomic.h1
-rw-r--r--arch/powerpc/include/asm/atomic.h1
-rw-r--r--arch/x86/include/asm/atomic.h24
-rw-r--r--include/linux/atomic.h25
4 files changed, 27 insertions, 24 deletions
diff --git a/arch/microblaze/include/asm/atomic.h b/arch/microblaze/include/asm/atomic.h
index 472d8bf726df..42ac382a09da 100644
--- a/arch/microblaze/include/asm/atomic.h
+++ b/arch/microblaze/include/asm/atomic.h
@@ -22,5 +22,6 @@ static inline int atomic_dec_if_positive(atomic_t *v)
return res;
}
+#define atomic_dec_if_positive atomic_dec_if_positive
#endif /* _ASM_MICROBLAZE_ATOMIC_H */
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index da29032ae38f..e3b1d41c89be 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -268,6 +268,7 @@ static __inline__ int atomic_dec_if_positive(atomic_t *v)
return t;
}
+#define atomic_dec_if_positive atomic_dec_if_positive
#define smp_mb__before_atomic_dec() smp_mb()
#define smp_mb__after_atomic_dec() smp_mb()
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index 250b8774c158..b6c3b821acf6 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -240,30 +240,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
return c;
}
-
-/*
- * atomic_dec_if_positive - decrement by 1 if old value positive
- * @v: pointer of type atomic_t
- *
- * The function returns the old value of *v minus 1, even if
- * the atomic variable, v, was not decremented.
- */
-static inline int atomic_dec_if_positive(atomic_t *v)
-{
- int c, old, dec;
- c = atomic_read(v);
- for (;;) {
- dec = c - 1;
- if (unlikely(dec < 0))
- break;
- old = atomic_cmpxchg((v), c, dec);
- if (likely(old == c))
- break;
- c = old;
- }
- return dec;
-}
-
/**
* atomic_inc_short - increment of a short integer
* @v: pointer to type int
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 70cfcb2d63c4..5b08a8540ecf 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -86,6 +86,31 @@ static inline int atomic_dec_unless_positive(atomic_t *p)
}
#endif
+/*
+ * atomic_dec_if_positive - decrement by 1 if old value positive
+ * @v: pointer of type atomic_t
+ *
+ * The function returns the old value of *v minus 1, even if
+ * the atomic variable, v, was not decremented.
+ */
+#ifndef atomic_dec_if_positive
+static inline int atomic_dec_if_positive(atomic_t *v)
+{
+ int c, old, dec;
+ c = atomic_read(v);
+ for (;;) {
+ dec = c - 1;
+ if (unlikely(dec < 0))
+ break;
+ old = atomic_cmpxchg((v), c, dec);
+ if (likely(old == c))
+ break;
+ c = old;
+ }
+ return dec;
+}
+#endif
+
#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
static inline void atomic_or(int i, atomic_t *v)
{