forked from luck/tmp_suning_uos_patched
[IA64] SMT friendly version of spin_unlock_wait()
We can be kinder to SMT systems in spin_unlock_wait. Signed-off-by: Tony Luck <tony.luck@intel.com>
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9d40ee200a
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1502f08edc
@ -75,6 +75,20 @@ static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock)
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ACCESS_ONCE(*p) = (tmp + 2) & ~1;
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}
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static __always_inline void __ticket_spin_unlock_wait(raw_spinlock_t *lock)
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{
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int *p = (int *)&lock->lock, ticket;
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ia64_invala();
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for (;;) {
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asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory");
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if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
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return;
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cpu_relax();
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}
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}
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static inline int __ticket_spin_is_locked(raw_spinlock_t *lock)
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{
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long tmp = ACCESS_ONCE(lock->lock);
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@ -123,8 +137,7 @@ static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock,
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static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
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{
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while (__raw_spin_is_locked(lock))
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cpu_relax();
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__ticket_spin_unlock_wait(lock);
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}
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#define __raw_read_can_lock(rw) (*(volatile int *)(rw) >= 0)
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