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| author | Heiko Carstens <hca@linux.ibm.com> | 2021-03-22 18:36:27 +0300 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2021-04-12 13:46:43 +0300 |
| commit | b23eb636d7f9f3d7c3ae0dd443cf26c4cc1e18f7 (patch) | |
| tree | 6cdb42880a4a6b8f3ba65cfae703cbe031523e8a | |
| parent | ca897bb1814fc77ce2ded7b31350ff2b25ccb0a4 (diff) | |
| download | linux-b23eb636d7f9f3d7c3ae0dd443cf26c4cc1e18f7.tar.xz | |
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: Heiko Carstens <hca@linux.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/atomic_ops.h | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/arch/s390/include/asm/atomic_ops.h b/arch/s390/include/asm/atomic_ops.h index 92ea9d9a2b93..2e818f2709bf 100644 --- a/arch/s390/include/asm/atomic_ops.h +++ b/arch/s390/include/asm/atomic_ops.h @@ -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__ */ |