diff options
Diffstat (limited to 'arch/ia64/include/asm/spinlock.h')
-rw-r--r-- | arch/ia64/include/asm/spinlock.h | 45 |
1 files changed, 26 insertions, 19 deletions
diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h index 30bb930e111..4fa502739d6 100644 --- a/arch/ia64/include/asm/spinlock.h +++ b/arch/ia64/include/asm/spinlock.h @@ -25,61 +25,68 @@ * by atomically noting the tail and incrementing it by one (thus adding * ourself to the queue and noting our position), then waiting until the head * becomes equal to the the initial value of the tail. + * The pad bits in the middle are used to prevent the next_ticket number + * overflowing into the now_serving number. * - * 63 32 31 0 + * 31 17 16 15 14 0 * +----------------------------------------------------+ - * | next_ticket_number | now_serving | + * | now_serving | padding | next_ticket | * +----------------------------------------------------+ */ -#define TICKET_SHIFT 32 +#define TICKET_SHIFT 17 +#define TICKET_BITS 15 +#define TICKET_MASK ((1 << TICKET_BITS) - 1) static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock) { - int *p = (int *)&lock->lock, turn, now_serving; + int *p = (int *)&lock->lock, ticket, serve; - now_serving = *p; - turn = ia64_fetchadd(1, p+1, acq); + ticket = ia64_fetchadd(1, p, acq); - if (turn == now_serving) + if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK)) return; - do { + ia64_invala(); + + for (;;) { + asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(p) : "memory"); + + if (!(((serve >> TICKET_SHIFT) ^ ticket) & TICKET_MASK)) + return; cpu_relax(); - } while (ACCESS_ONCE(*p) != turn); + } } static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock) { - long tmp = ACCESS_ONCE(lock->lock), try; + int tmp = ACCESS_ONCE(lock->lock); - if (!(((tmp >> TICKET_SHIFT) ^ tmp) & ((1L << TICKET_SHIFT) - 1))) { - try = tmp + (1L << TICKET_SHIFT); - - return ia64_cmpxchg(acq, &lock->lock, tmp, try, sizeof (tmp)) == tmp; - } + if (!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK)) + return ia64_cmpxchg(acq, &lock->lock, tmp, tmp + 1, sizeof (tmp)) == tmp; return 0; } static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock) { - int *p = (int *)&lock->lock; + unsigned short *p = (unsigned short *)&lock->lock + 1, tmp; - (void)ia64_fetchadd(1, p, rel); + asm volatile ("ld2.bias %0=[%1]" : "=r"(tmp) : "r"(p)); + ACCESS_ONCE(*p) = (tmp + 2) & ~1; } static inline int __ticket_spin_is_locked(raw_spinlock_t *lock) { long tmp = ACCESS_ONCE(lock->lock); - return !!(((tmp >> TICKET_SHIFT) ^ tmp) & ((1L << TICKET_SHIFT) - 1)); + return !!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK); } static inline int __ticket_spin_is_contended(raw_spinlock_t *lock) { long tmp = ACCESS_ONCE(lock->lock); - return (((tmp >> TICKET_SHIFT) - tmp) & ((1L << TICKET_SHIFT) - 1)) > 1; + return ((tmp - (tmp >> TICKET_SHIFT)) & TICKET_MASK) > 1; } static inline int __raw_spin_is_locked(raw_spinlock_t *lock) |