locking/atomic, arch/parisc: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()

Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.

This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Helge Deller <deller@gmx.de>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 57 insertions, 8 deletions

diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h
index 1d109990a022..29df1f871910 100644
--- a/arch/parisc/include/asm/atomic.h
+++ b/arch/parisc/include/asm/atomic.h
@@ -121,16 +121,41 @@ static __inline__ int atomic_##op##_return(int i, atomic_t *v)		\
         return ret;                                                     \
 }
 
-#define ATOMIC_OPS(op, c_op) ATOMIC_OP(op, c_op) ATOMIC_OP_RETURN(op, c_op)
+#define ATOMIC_FETCH_OP(op, c_op)                                       \
+static __inline__ int atomic_fetch_##op(int i, atomic_t *v)             \
+{                                                                       \
+        unsigned long flags;                                            \
+        int ret;                                                        \
+                                                                        \
+        _atomic_spin_lock_irqsave(v, flags);                            \
+        ret = v->counter;                                               \
+        v->counter c_op i;                                              \
+        _atomic_spin_unlock_irqrestore(v, flags);                       \
+                                                                        \
+        return ret;                                                     \
+}
+
+#define ATOMIC_OPS(op, c_op)                                            \
+        ATOMIC_OP(op, c_op)                                             \
+        ATOMIC_OP_RETURN(op, c_op)                                      \
+        ATOMIC_FETCH_OP(op, c_op)
 
 ATOMIC_OPS(add, +=)
 ATOMIC_OPS(sub, -=)
 
-ATOMIC_OP(and, &=)
-ATOMIC_OP(or, |=)
-ATOMIC_OP(xor, ^=)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op, c_op)                                            \
+        ATOMIC_OP(op, c_op)                                             \
+        ATOMIC_FETCH_OP(op, c_op)
+
+#define atomic_fetch_or atomic_fetch_or
+
+ATOMIC_OPS(and, &=)
+ATOMIC_OPS(or, |=)
+ATOMIC_OPS(xor, ^=)
 
 #undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
 #undef ATOMIC_OP_RETURN
 #undef ATOMIC_OP
 
@@ -185,15 +210,39 @@ static __inline__ s64 atomic64_##op##_return(s64 i, atomic64_t *v)	\
         return ret;                                                     \
 }
 
-#define ATOMIC64_OPS(op, c_op) ATOMIC64_OP(op, c_op) ATOMIC64_OP_RETURN(op, c_op)
+#define ATOMIC64_FETCH_OP(op, c_op)                                     \
+static __inline__ s64 atomic64_fetch_##op(s64 i, atomic64_t *v)         \
+{                                                                       \
+        unsigned long flags;                                            \
+        s64 ret;                                                        \
+                                                                        \
+        _atomic_spin_lock_irqsave(v, flags);                            \
+        ret = v->counter;                                               \
+        v->counter c_op i;                                              \
+        _atomic_spin_unlock_irqrestore(v, flags);                       \
+                                                                        \
+        return ret;                                                     \
+}
+
+#define ATOMIC64_OPS(op, c_op)                                          \
+        ATOMIC64_OP(op, c_op)                                           \
+        ATOMIC64_OP_RETURN(op, c_op)                                    \
+        ATOMIC64_FETCH_OP(op, c_op)
 
 ATOMIC64_OPS(add, +=)
 ATOMIC64_OPS(sub, -=)
-ATOMIC64_OP(and, &=)
-ATOMIC64_OP(or, |=)
-ATOMIC64_OP(xor, ^=)
 
 #undef ATOMIC64_OPS
+#define ATOMIC64_OPS(op, c_op)                                          \
+        ATOMIC64_OP(op, c_op)                                           \
+        ATOMIC64_FETCH_OP(op, c_op)
+
+ATOMIC64_OPS(and, &=)
+ATOMIC64_OPS(or, |=)
+ATOMIC64_OPS(xor, ^=)
+
+#undef ATOMIC64_OPS
+#undef ATOMIC64_FETCH_OP
 #undef ATOMIC64_OP_RETURN
 #undef ATOMIC64_OP