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Commit 1502f08e authored by Tony Luck's avatar Tony Luck
Browse files

[IA64] SMT friendly version of spin_unlock_wait() 



We can be kinder to SMT systems in spin_unlock_wait.

Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 9d40ee20

arch/ia64/include/asm/spinlock.h

+15 −2
Original line number Diff line number Diff line
@@ -75,6 +75,20 @@ static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock) 
	ACCESS_ONCE(*p) = (tmp + 2) & ~1;

}



static __always_inline void __ticket_spin_unlock_wait(raw_spinlock_t *lock)

{

	int	*p = (int *)&lock->lock, ticket;



	ia64_invala();



	for (;;) {

		asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory");

		if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))

			return;

		cpu_relax();

	}

}



static inline int __ticket_spin_is_locked(raw_spinlock_t *lock)

{

	long tmp = ACCESS_ONCE(lock->lock);
@@ -123,8 +137,7 @@ static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock, 


static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)

{

	while (__raw_spin_is_locked(lock))

		cpu_relax();

	__ticket_spin_unlock_wait(lock);

}



#define __raw_read_can_lock(rw)		(*(volatile int *)(rw) >= 0)