[PATCH 4/4 V4] qspinlock for x86: smp_mb__after_spin_lock() is free

For x86 qspinlocks, no additional memory barrier is required in smp_mb__after_spin_lock: Theoretically, for qspinlock we could define two barriers: - smp_mb__after_spin_lock: Free for x86, not free for powerpc - smp_mb__between_spin_lock_and_spin_unlock_wait(): Free for all archs, see

[PATCH 4/4 V4] qspinlock for x86: smp_mb__after_spin_lock() is free

For x86 qspinlocks, no additional memory barrier is required in smp_mb__after_spin_lock: Theoretically, for qspinlock we could define two barriers: - smp_mb__after_spin_lock: Free for x86, not free for powerpc - smp_mb__between_spin_lock_and_spin_unlock_wait(): Free for all archs, see