Commit b23eb636 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390/atomic: get rid of gcc atomic builtins 

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: default avatarHeiko Carstens <hca@linux.ibm.com>
parent ca897bb1

arch/s390/include/asm/atomic_ops.h

+30 −6
Original line number Diff line number Diff line
@@ -156,22 +156,46 @@ __ATOMIC64_OPS(__atomic64_xor, "xgr") 


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)

{

	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__  */