locking/atomic, arch/m32r: Implement atomic_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: 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
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/m32r/include/asm/atomic.h b/arch/m32r/include/asm/atomic.h
index ea35160..8ba8a0a 100644 (file)
--- a/arch/m32r/include/asm/atomic.h
+++ b/arch/m32r/include/asm/atomic.h
@@ -89,16 +89,46 @@ static __inline__ int atomic_##op##_return(int i, atomic_t *v)              \
        return result;                                                  \
 }
 
-#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
+#define ATOMIC_FETCH_OP(op)                                            \
+static __inline__ int atomic_fetch_##op(int i, atomic_t *v)            \
+{                                                                      \
+       unsigned long flags;                                            \
+       int result, val;                                                \
+                                                                       \
+       local_irq_save(flags);                                          \
+       __asm__ __volatile__ (                                          \
+               "# atomic_fetch_" #op "         \n\t"                   \
+               DCACHE_CLEAR("%0", "r4", "%2")                          \
+               M32R_LOCK" %1, @%2;             \n\t"                   \
+               "mv %0, %1                      \n\t"                   \
+               #op " %1, %3;                   \n\t"                   \
+               M32R_UNLOCK" %1, @%2;           \n\t"                   \
+               : "=&r" (result), "=&r" (val)                           \
+               : "r" (&v->counter), "r" (i)                            \
+               : "memory"                                              \
+               __ATOMIC_CLOBBER                                        \
+       );                                                              \
+       local_irq_restore(flags);                                       \
+                                                                       \
+       return result;                                                  \
+}
+
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
 
 ATOMIC_OPS(add)
 ATOMIC_OPS(sub)
 
-ATOMIC_OP(and)
-ATOMIC_OP(or)
-ATOMIC_OP(xor)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(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