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jump_label: Use atomic_try_cmpxchg() in static_key_slow_inc_cpuslocked()
Use atomic_try_cmpxchg() instead of atomic_cmpxchg (*ptr, old, new) == old in static_key_slow_inc_cpuslocked(). x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, atomic_try_cmpxchg() implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications. No functional change intended. Signed-off-by: Uros Bizjak <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
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