| Subject | Re: [PATCH RFC ticketlock] Auto-queued ticketlock | From | Steven Rostedt <> | Date | Mon, 10 Jun 2013 17:08:25 -0400 |
| |
On Sun, 2013-06-09 at 12:36 -0700, Paul E. McKenney wrote: > > +#else /* #ifndef CONFIG_TICKET_LOCK_QUEUED */ > + > +bool tkt_spin_pass(arch_spinlock_t *ap, struct __raw_tickets inc); > + > +static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) > +{ > + register struct __raw_tickets inc = { .tail = 2 }; > + > + inc = xadd(&lock->tickets, inc); > + for (;;) { > + if (inc.head == inc.tail || tkt_spin_pass(lock, inc)) > + break; > + inc.head = ACCESS_ONCE(lock->tickets.head); > + } > + barrier(); /* smp_mb() on Power or ARM. */ > +} > + > +#endif /* #else #ifndef CONFIG_TICKET_LOCK_QUEUED */ > +
To avoid the above code duplication, I would have this instead:
#ifdef CONFIG_TICKET_LOCK_QUEUED
bool tkt_spin_pass(arch_spinlock_t *ap, struct __raw_tickets inc); #define __TKT_SPIN_INC 2
#else
static inline bool tkt_spin_pass(arch_spinlock_t *ap, struct __raw_tickets inc) { return false; }
#define __TKT_SPIN_INC 1
#endif
static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { register struct __raw_tickets inc = { .tail = __TKT_SPIN_INC };
inc = xadd(&lock->tickets, inc);
for (;;) { if (inc.head == inc.tail || tkt_spin_pass(lock, inc)) break; cpu_relax(); inc.head = ACCESS_ONCE(lock->tickets.head); } barrier; /* make sure nothing creeps before the lock is taken */ }
-- Steve
|