s390/atomic: implement atomic_sub_return() with atomic_add_return()

Get rid of the own atomic_sub_return() implementation. Otherwise we can't
make use of the interlocked-access facility 1 instructions for
atomic_sub_return(), since there is no "load and subtract" instruction
available.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/include/asm/atomic.h b/arch/s390/include/asm/atomic.h
index c797832daa5f596bac9da8f5075d1bd2e006559c..fea2c8887da5238ddeb117782f2338767572e00a 100644 (file)
--- a/arch/s390/include/asm/atomic.h
+++ b/arch/s390/include/asm/atomic.h
@@ -60,11 +60,7 @@ static inline int atomic_add_return(int i, atomic_t *v)
 #define atomic_inc(_v)                 atomic_add_return(1, _v)
 #define atomic_inc_return(_v)          atomic_add_return(1, _v)
 #define atomic_inc_and_test(_v)                (atomic_add_return(1, _v) == 0)
-
-static inline int atomic_sub_return(int i, atomic_t *v)
-{
-       return __CS_LOOP(v, i, "sr");
-}
+#define atomic_sub_return(_i, _v)      atomic_add_return(-(int)(_i), _v)
 #define atomic_sub(_i, _v)             atomic_sub_return(_i, _v)
 #define atomic_sub_and_test(_i, _v)    (atomic_sub_return(_i, _v) == 0)
 #define atomic_dec(_v)                 atomic_sub_return(1, _v)
@@ -152,11 +148,6 @@ static inline long long atomic64_add_return(long long i, atomic64_t *v)
        return __CSG_LOOP(v, i, "agr");
 }
 
-static inline long long atomic64_sub_return(long long i, atomic64_t *v)
-{
-       return __CSG_LOOP(v, i, "sgr");
-}
-
 static inline void atomic64_clear_mask(unsigned long mask, atomic64_t *v)
 {
        __CSG_LOOP(v, ~mask, "ngr");
@@ -248,17 +239,6 @@ static inline long long atomic64_add_return(long long i, atomic64_t *v)
        return new;
 }
 
-static inline long long atomic64_sub_return(long long i, atomic64_t *v)
-{
-       long long old, new;
-
-       do {
-               old = atomic64_read(v);
-               new = old - i;
-       } while (atomic64_cmpxchg(v, old, new) != old);
-       return new;
-}
-
 static inline void atomic64_set_mask(unsigned long long mask, atomic64_t *v)
 {
        long long old, new;
@@ -319,6 +299,7 @@ static inline long long atomic64_dec_if_positive(atomic64_t *v)
 #define atomic64_inc(_v)               atomic64_add_return(1, _v)
 #define atomic64_inc_return(_v)                atomic64_add_return(1, _v)
 #define atomic64_inc_and_test(_v)      (atomic64_add_return(1, _v) == 0)
+#define atomic64_sub_return(_i, _v)    atomic64_add_return(-(long long)(_i), _v)
 #define atomic64_sub(_i, _v)           atomic64_sub_return(_i, _v)
 #define atomic64_sub_and_test(_i, _v)  (atomic64_sub_return(_i, _v) == 0)
 #define atomic64_dec(_v)               atomic64_sub_return(1, _v)