LXR linux/arch/powerpc/include/asm/qspinlock.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_POWERPC_QSPINLOCK_H
   3#define _ASM_POWERPC_QSPINLOCK_H
   4
   5#include <asm-generic/qspinlock_types.h>
   6#include <asm/paravirt.h>
   7
   8#define _Q_PENDING_LOOPS        (1 << 9) /* not tuned */
   9
  10#ifdef CONFIG_PARAVIRT_SPINLOCKS
  11extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
  12extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
  13extern void __pv_queued_spin_unlock(struct qspinlock *lock);
  14
  15static __always_inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
  16{
  17        if (!is_shared_processor())
  18                native_queued_spin_lock_slowpath(lock, val);
  19        else
  20                __pv_queued_spin_lock_slowpath(lock, val);
  21}
  22
  23#define queued_spin_unlock queued_spin_unlock
  24static inline void queued_spin_unlock(struct qspinlock *lock)
  25{
  26        if (!is_shared_processor())
  27                smp_store_release(&lock->locked, 0);
  28        else
  29                __pv_queued_spin_unlock(lock);
  30}
  31
  32#else
  33extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
  34#endif
  35
  36static __always_inline void queued_spin_lock(struct qspinlock *lock)
  37{
  38        u32 val = 0;
  39
  40        if (likely(arch_atomic_try_cmpxchg_lock(&lock->val, &val, _Q_LOCKED_VAL)))
  41                return;
  42
  43        queued_spin_lock_slowpath(lock, val);
  44}
  45#define queued_spin_lock queued_spin_lock
  46
  47#ifdef CONFIG_PARAVIRT_SPINLOCKS
  48#define SPIN_THRESHOLD (1<<15) /* not tuned */
  49
  50static __always_inline void pv_wait(u8 *ptr, u8 val)
  51{
  52        if (*ptr != val)
  53                return;
  54        yield_to_any();
  55        /*
  56         * We could pass in a CPU here if waiting in the queue and yield to
  57         * the previous CPU in the queue.
  58         */
  59}
  60
  61static __always_inline void pv_kick(int cpu)
  62{
  63        prod_cpu(cpu);
  64}
  65
  66extern void __pv_init_lock_hash(void);
  67
  68static inline void pv_spinlocks_init(void)
  69{
  70        __pv_init_lock_hash();
  71}
  72
  73#endif
  74
  75/*
  76 * Queued spinlocks rely heavily on smp_cond_load_relaxed() to busy-wait,
  77 * which was found to have performance problems if implemented with
  78 * the preferred spin_begin()/spin_end() SMT priority pattern. Use the
  79 * generic version instead.
  80 */
  81
  82#include <asm-generic/qspinlock.h>
  83
  84#endif /* _ASM_POWERPC_QSPINLOCK_H */
  85