locking/atomic, arch/avr32: 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>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
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/avr32/include/asm/atomic.h b/arch/avr32/include/asm/atomic.h
index d74fd8c..b8681fd 100644 (file)
--- a/arch/avr32/include/asm/atomic.h
+++ b/arch/avr32/include/asm/atomic.h
@@ -41,21 +41,51 @@ static inline int __atomic_##op##_return(int i, atomic_t *v)                \
        return result;                                                  \
 }
 
+#define ATOMIC_FETCH_OP(op, asm_op, asm_con)                           \
+static inline int __atomic_fetch_##op(int i, atomic_t *v)              \
+{                                                                      \
+       int result, val;                                                \
+                                                                       \
+       asm volatile(                                                   \
+               "/* atomic_fetch_" #op " */\n"                          \
+               "1:     ssrf    5\n"                                    \
+               "       ld.w    %0, %3\n"                               \
+               "       mov     %1, %0\n"                               \
+               "       " #asm_op "     %1, %4\n"                       \
+               "       stcond  %2, %1\n"                               \
+               "       brne    1b"                                     \
+               : "=&r" (result), "=&r" (val), "=o" (v->counter)        \
+               : "m" (v->counter), #asm_con (i)                        \
+               : "cc");                                                \
+                                                                       \
+       return result;                                                  \
+}
+
 ATOMIC_OP_RETURN(sub, sub, rKs21)
 ATOMIC_OP_RETURN(add, add, r)
+ATOMIC_FETCH_OP (sub, sub, rKs21)
+ATOMIC_FETCH_OP (add, add, r)
+
+#define atomic_fetch_or atomic_fetch_or
 
-#define ATOMIC_OP(op, asm_op)                                          \
+#define ATOMIC_OPS(op, asm_op)                                         \
 ATOMIC_OP_RETURN(op, asm_op, r)                                                \
 static inline void atomic_##op(int i, atomic_t *v)                     \
 {                                                                      \
        (void)__atomic_##op##_return(i, v);                             \
+}                                                                      \
+ATOMIC_FETCH_OP(op, asm_op, r)                                         \
+static inline int atomic_fetch_##op(int i, atomic_t *v)                \
+{                                                                      \
+       return __atomic_fetch_##op(i, v);                               \
 }
 
-ATOMIC_OP(and, and)
-ATOMIC_OP(or, or)
-ATOMIC_OP(xor, eor)
+ATOMIC_OPS(and, and)
+ATOMIC_OPS(or, or)
+ATOMIC_OPS(xor, eor)
 
-#undef ATOMIC_OP
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
 #undef ATOMIC_OP_RETURN
 
 /*
@@ -87,6 +117,14 @@ static inline int atomic_add_return(int i, atomic_t *v)
        return __atomic_add_return(i, v);
 }
 
+static inline int atomic_fetch_add(int i, atomic_t *v)
+{
+       if (IS_21BIT_CONST(i))
+               return __atomic_fetch_sub(-i, v);
+
+       return __atomic_fetch_add(i, v);
+}
+
 /*
  * atomic_sub_return - subtract the atomic variable
  * @i: integer value to subtract
@@ -102,6 +140,14 @@ static inline int atomic_sub_return(int i, atomic_t *v)
        return __atomic_add_return(-i, v);
 }
 
+static inline int atomic_fetch_sub(int i, atomic_t *v)
+{
+       if (IS_21BIT_CONST(i))
+               return __atomic_fetch_sub(i, v);
+
+       return __atomic_fetch_add(-i, v);
+}
+
 /*
  * __atomic_add_unless - add unless the number is a given value
  * @v: pointer of type atomic_t