![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
192 lines
4.6 KiB
C
192 lines
4.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Generic implementation of 64-bit atomics using spinlocks,
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* useful on processors that don't have 64-bit atomic instructions.
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*
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* Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
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*/
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#include <linux/types.h>
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#include <linux/cache.h>
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#include <linux/spinlock.h>
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/atomic.h>
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/*
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* We use a hashed array of spinlocks to provide exclusive access
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* to each atomic64_t variable. Since this is expected to used on
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* systems with small numbers of CPUs (<= 4 or so), we use a
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* relatively small array of 16 spinlocks to avoid wasting too much
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* memory on the spinlock array.
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*/
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#define NR_LOCKS 16
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/*
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* Ensure each lock is in a separate cacheline.
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*/
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static union {
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raw_spinlock_t lock;
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char pad[L1_CACHE_BYTES];
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} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = {
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[0 ... (NR_LOCKS - 1)] = {
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.lock = __RAW_SPIN_LOCK_UNLOCKED(atomic64_lock.lock),
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},
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};
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static inline raw_spinlock_t *lock_addr(const atomic64_t *v)
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{
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unsigned long addr = (unsigned long) v;
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addr >>= L1_CACHE_SHIFT;
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addr ^= (addr >> 8) ^ (addr >> 16);
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return &atomic64_lock[addr & (NR_LOCKS - 1)].lock;
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}
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long long atomic64_read(const atomic64_t *v)
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{
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unsigned long flags;
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raw_spinlock_t *lock = lock_addr(v);
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long long val;
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raw_spin_lock_irqsave(lock, flags);
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val = v->counter;
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raw_spin_unlock_irqrestore(lock, flags);
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return val;
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}
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EXPORT_SYMBOL(atomic64_read);
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void atomic64_set(atomic64_t *v, long long i)
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{
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unsigned long flags;
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raw_spinlock_t *lock = lock_addr(v);
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raw_spin_lock_irqsave(lock, flags);
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v->counter = i;
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raw_spin_unlock_irqrestore(lock, flags);
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}
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EXPORT_SYMBOL(atomic64_set);
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#define ATOMIC64_OP(op, c_op) \
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void atomic64_##op(long long a, atomic64_t *v) \
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{ \
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unsigned long flags; \
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raw_spinlock_t *lock = lock_addr(v); \
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\
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raw_spin_lock_irqsave(lock, flags); \
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v->counter c_op a; \
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raw_spin_unlock_irqrestore(lock, flags); \
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} \
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EXPORT_SYMBOL(atomic64_##op);
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#define ATOMIC64_OP_RETURN(op, c_op) \
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long long atomic64_##op##_return(long long a, atomic64_t *v) \
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{ \
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unsigned long flags; \
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raw_spinlock_t *lock = lock_addr(v); \
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long long val; \
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\
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raw_spin_lock_irqsave(lock, flags); \
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val = (v->counter c_op a); \
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raw_spin_unlock_irqrestore(lock, flags); \
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return val; \
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} \
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EXPORT_SYMBOL(atomic64_##op##_return);
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#define ATOMIC64_FETCH_OP(op, c_op) \
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long long atomic64_fetch_##op(long long a, atomic64_t *v) \
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{ \
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unsigned long flags; \
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raw_spinlock_t *lock = lock_addr(v); \
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long long val; \
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\
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raw_spin_lock_irqsave(lock, flags); \
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val = v->counter; \
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v->counter c_op a; \
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raw_spin_unlock_irqrestore(lock, flags); \
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return val; \
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} \
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EXPORT_SYMBOL(atomic64_fetch_##op);
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#define ATOMIC64_OPS(op, c_op) \
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ATOMIC64_OP(op, c_op) \
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ATOMIC64_OP_RETURN(op, c_op) \
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ATOMIC64_FETCH_OP(op, c_op)
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ATOMIC64_OPS(add, +=)
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ATOMIC64_OPS(sub, -=)
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#undef ATOMIC64_OPS
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#define ATOMIC64_OPS(op, c_op) \
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ATOMIC64_OP(op, c_op) \
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ATOMIC64_OP_RETURN(op, c_op) \
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ATOMIC64_FETCH_OP(op, c_op)
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ATOMIC64_OPS(and, &=)
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ATOMIC64_OPS(or, |=)
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ATOMIC64_OPS(xor, ^=)
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#undef ATOMIC64_OPS
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#undef ATOMIC64_FETCH_OP
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#undef ATOMIC64_OP_RETURN
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#undef ATOMIC64_OP
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long long atomic64_dec_if_positive(atomic64_t *v)
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{
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unsigned long flags;
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raw_spinlock_t *lock = lock_addr(v);
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long long val;
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raw_spin_lock_irqsave(lock, flags);
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val = v->counter - 1;
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if (val >= 0)
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v->counter = val;
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raw_spin_unlock_irqrestore(lock, flags);
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return val;
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}
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EXPORT_SYMBOL(atomic64_dec_if_positive);
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long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n)
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{
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unsigned long flags;
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raw_spinlock_t *lock = lock_addr(v);
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long long val;
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raw_spin_lock_irqsave(lock, flags);
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val = v->counter;
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if (val == o)
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v->counter = n;
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raw_spin_unlock_irqrestore(lock, flags);
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return val;
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}
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EXPORT_SYMBOL(atomic64_cmpxchg);
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long long atomic64_xchg(atomic64_t *v, long long new)
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{
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unsigned long flags;
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raw_spinlock_t *lock = lock_addr(v);
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long long val;
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raw_spin_lock_irqsave(lock, flags);
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val = v->counter;
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v->counter = new;
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raw_spin_unlock_irqrestore(lock, flags);
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return val;
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}
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EXPORT_SYMBOL(atomic64_xchg);
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long long atomic64_fetch_add_unless(atomic64_t *v, long long a, long long u)
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{
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unsigned long flags;
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raw_spinlock_t *lock = lock_addr(v);
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long long val;
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raw_spin_lock_irqsave(lock, flags);
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val = v->counter;
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if (val != u)
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v->counter += a;
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raw_spin_unlock_irqrestore(lock, flags);
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return val;
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}
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EXPORT_SYMBOL(atomic64_fetch_add_unless);
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