From 0cbad9c9dfe0c38e8ec7385b39087c005a6dee3e Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 9 Oct 2013 17:19:22 +0100 Subject: ARM: 7854/1: lockref: add support for lockless lockrefs using cmpxchg64 Our spinlocks are only 32-bit (2x16-bit tickets) and, on processors with 64-bit atomic instructions, cmpxchg64 makes use of the double-word exclusive accessors. This patch wires up the cmpxchg-based lockless lockref implementation for ARM. Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/include/asm/spinlock.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/arm/include/asm/spinlock.h') diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h index 4f2c28060c9a..ed6c22919e47 100644 --- a/arch/arm/include/asm/spinlock.h +++ b/arch/arm/include/asm/spinlock.h @@ -127,10 +127,14 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock) dsb_sev(); } +static inline int arch_spin_value_unlocked(arch_spinlock_t lock) +{ + return lock.tickets.owner == lock.tickets.next; +} + static inline int arch_spin_is_locked(arch_spinlock_t *lock) { - struct __raw_tickets tickets = ACCESS_ONCE(lock->tickets); - return tickets.owner != tickets.next; + return !arch_spin_value_unlocked(ACCESS_ONCE(*lock)); } static inline int arch_spin_is_contended(arch_spinlock_t *lock) -- cgit