s390 is the only architecture in the kernel which makes use of gcc's
atomic builtin functions. Even though I don't see any technical
problem with that right now, remove this code and open-code
compare-and-swap loops again, like every other architecture is doing
it also.
We can switch to a generic implementation when other architectures are
doing that also.
See also https://lwn.net/Articles/586838/ for forther details.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
static inline int __atomic_cmpxchg(int *ptr, int old, int new)
{
static inline int __atomic_cmpxchg(int *ptr, int old, int new)
{
- return __sync_val_compare_and_swap(ptr, old, new);
+ asm volatile(
+ " cs %[old],%[new],%[ptr]"
+ : [old] "+d" (old), [ptr] "+Q" (*ptr)
+ : [new] "d" (new)
+ : "cc", "memory");
+ return old;
-static inline int __atomic_cmpxchg_bool(int *ptr, int old, int new)
+static inline bool __atomic_cmpxchg_bool(int *ptr, int old, int new)
- return __sync_bool_compare_and_swap(ptr, old, new);
+ int old_expected = old;
+
+ asm volatile(
+ " cs %[old],%[new],%[ptr]"
+ : [old] "+d" (old), [ptr] "+Q" (*ptr)
+ : [new] "d" (new)
+ : "cc", "memory");
+ return old == old_expected;
}
static inline long __atomic64_cmpxchg(long *ptr, long old, long new)
{
}
static inline long __atomic64_cmpxchg(long *ptr, long old, long new)
{
- return __sync_val_compare_and_swap(ptr, old, new);
+ asm volatile(
+ " csg %[old],%[new],%[ptr]"
+ : [old] "+d" (old), [ptr] "+S" (*ptr)
+ : [new] "d" (new)
+ : "cc", "memory");
+ return old;
-static inline long __atomic64_cmpxchg_bool(long *ptr, long old, long new)
+static inline bool __atomic64_cmpxchg_bool(long *ptr, long old, long new)
- return __sync_bool_compare_and_swap(ptr, old, new);
+ long old_expected = old;
+
+ asm volatile(
+ " csg %[old],%[new],%[ptr]"
+ : [old] "+d" (old), [ptr] "+S" (*ptr)
+ : [new] "d" (new)
+ : "cc", "memory");
+ return old == old_expected;
}
#endif /* __ARCH_S390_ATOMIC_OPS__ */
}
#endif /* __ARCH_S390_ATOMIC_OPS__ */