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authorAnton Blanchard <anton@samba.org>2012-02-29 21:12:16 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-03-07 17:06:08 +1100
commita6cf7ed5119fb22f54584a9f867b638edd3c4384 (patch)
tree5a81f3e6cf92caa6e806e2a5b945406902e63e07 /arch/powerpc/include/asm/atomic.h
parentb1ada6010e234d6c53bfcd5a617610c9284846b8 (diff)
powerpc/atomic: Implement atomic*_inc_not_zero
Implement atomic_inc_not_zero and atomic64_inc_not_zero. At the moment we use atomic*_add_unless which requires us to put 0 and 1 constants into registers. We can also avoid a subtract by saving the original value in a second temporary. This removes 3 instructions from fget: - c0000000001b63c0: 39 00 00 00 li r8,0 - c0000000001b63c4: 39 40 00 01 li r10,1 ... - c0000000001b63e8: 7c 0a 00 50 subf r0,r10,r0 Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/include/asm/atomic.h')
-rw-r--r--arch/powerpc/include/asm/atomic.h59
1 files changed, 58 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index 02e41b53488..14174e838ad 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -212,6 +212,36 @@ static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
return t;
}
+/**
+ * atomic_inc_not_zero - increment unless the number is zero
+ * @v: pointer of type atomic_t
+ *
+ * Atomically increments @v by 1, so long as @v is non-zero.
+ * Returns non-zero if @v was non-zero, and zero otherwise.
+ */
+static __inline__ int atomic_inc_not_zero(atomic_t *v)
+{
+ int t1, t2;
+
+ __asm__ __volatile__ (
+ PPC_ATOMIC_ENTRY_BARRIER
+"1: lwarx %0,0,%2 # atomic_inc_not_zero\n\
+ cmpwi 0,%0,0\n\
+ beq- 2f\n\
+ addic %1,%0,1\n"
+ PPC405_ERR77(0,%2)
+" stwcx. %1,0,%2\n\
+ bne- 1b\n"
+ PPC_ATOMIC_EXIT_BARRIER
+ "\n\
+2:"
+ : "=&r" (t1), "=&r" (t2)
+ : "r" (&v->counter)
+ : "cc", "xer", "memory");
+
+ return t1;
+}
+#define atomic_inc_not_zero(v) atomic_inc_not_zero((v))
#define atomic_sub_and_test(a, v) (atomic_sub_return((a), (v)) == 0)
#define atomic_dec_and_test(v) (atomic_dec_return((v)) == 0)
@@ -467,7 +497,34 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
return t != u;
}
-#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
+/**
+ * atomic_inc64_not_zero - increment unless the number is zero
+ * @v: pointer of type atomic64_t
+ *
+ * Atomically increments @v by 1, so long as @v is non-zero.
+ * Returns non-zero if @v was non-zero, and zero otherwise.
+ */
+static __inline__ long atomic64_inc_not_zero(atomic64_t *v)
+{
+ long t1, t2;
+
+ __asm__ __volatile__ (
+ PPC_ATOMIC_ENTRY_BARRIER
+"1: ldarx %0,0,%2 # atomic64_inc_not_zero\n\
+ cmpdi 0,%0,0\n\
+ beq- 2f\n\
+ addic %1,%0,1\n\
+ stdcx. %1,0,%2\n\
+ bne- 1b\n"
+ PPC_ATOMIC_EXIT_BARRIER
+ "\n\
+2:"
+ : "=&r" (t1), "=&r" (t2)
+ : "r" (&v->counter)
+ : "cc", "xer", "memory");
+
+ return t1;
+}
#endif /* __powerpc64__ */