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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208// SPDX-License-Identifier: GPL-2.0-or-later/* * Generic implementation of 64-bit atomics using spinlocks, * useful on processors that don't have 64-bit atomic instructions. * * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com> */#include <linux/types.h>#include <linux/cache.h>#include <linux/spinlock.h>#include <linux/init.h>#include <linux/export.h>#include <linux/atomic.h>
/* * We use a hashed array of spinlocks to provide exclusive access * to each atomic64_t variable. Since this is expected to used on * systems with small numbers of CPUs (<= 4 or so), we use a * relatively small array of 16 spinlocks to avoid wasting too much * memory on the spinlock array. */#define NR_LOCKS 16
/* * Ensure each lock is in a separate cacheline. */static union { arch_spinlock_t lock; char pad[L1_CACHE_BYTES];} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = { [0 ... (NR_LOCKS - 1)] = { .lock = __ARCH_SPIN_LOCK_UNLOCKED, },};
static inline arch_spinlock_t *lock_addr(const atomic64_t *v){ unsigned long addr = (unsigned long) v;
addr >>= L1_CACHE_SHIFT; addr ^= (addr >> 8) ^ (addr >> 16); return &atomic64_lock[addr & (NR_LOCKS - 1)].lock;}
s64 generic_atomic64_read(const atomic64_t *v){ unsigned long flags; arch_spinlock_t *lock = lock_addr(v); s64 val;
local_irq_save(flags); arch_spin_lock(lock); val = v->counter; arch_spin_unlock(lock); local_irq_restore(flags); return val;}EXPORT_SYMBOL(generic_atomic64_read);
void generic_atomic64_set(atomic64_t *v, s64 i){ unsigned long flags; arch_spinlock_t *lock = lock_addr(v);
local_irq_save(flags); arch_spin_lock(lock); v->counter = i; arch_spin_unlock(lock); local_irq_restore(flags);}EXPORT_SYMBOL(generic_atomic64_set);
#define ATOMIC64_OP(op, c_op) \void generic_atomic64_##op(s64 a, atomic64_t *v) \{ \ unsigned long flags; \ arch_spinlock_t *lock = lock_addr(v); \ \ local_irq_save(flags); \ arch_spin_lock(lock); \ v->counter c_op a; \ arch_spin_unlock(lock); \ local_irq_restore(flags); \} \EXPORT_SYMBOL(generic_atomic64_##op);
#define ATOMIC64_OP_RETURN(op, c_op) \s64 generic_atomic64_##op##_return(s64 a, atomic64_t *v) \{ \ unsigned long flags; \ arch_spinlock_t *lock = lock_addr(v); \ s64 val; \ \ local_irq_save(flags); \ arch_spin_lock(lock); \ val = (v->counter c_op a); \ arch_spin_unlock(lock); \ local_irq_restore(flags); \ return val; \} \EXPORT_SYMBOL(generic_atomic64_##op##_return);
#define ATOMIC64_FETCH_OP(op, c_op) \s64 generic_atomic64_fetch_##op(s64 a, atomic64_t *v) \{ \ unsigned long flags; \ arch_spinlock_t *lock = lock_addr(v); \ s64 val; \ \ local_irq_save(flags); \ arch_spin_lock(lock); \ val = v->counter; \ v->counter c_op a; \ arch_spin_unlock(lock); \ local_irq_restore(flags); \ return val; \} \EXPORT_SYMBOL(generic_atomic64_fetch_##op);
#define ATOMIC64_OPS(op, c_op) \ ATOMIC64_OP(op, c_op) \ ATOMIC64_OP_RETURN(op, c_op) \ ATOMIC64_FETCH_OP(op, c_op)
ATOMIC64_OPS(add, +=)ATOMIC64_OPS(sub, -=)
#undef ATOMIC64_OPS#define ATOMIC64_OPS(op, c_op) \ ATOMIC64_OP(op, c_op) \ ATOMIC64_FETCH_OP(op, c_op)
ATOMIC64_OPS(and, &=)ATOMIC64_OPS(or, |=)ATOMIC64_OPS(xor, ^=)
#undef ATOMIC64_OPS#undef ATOMIC64_FETCH_OP#undef ATOMIC64_OP
s64 generic_atomic64_dec_if_positive(atomic64_t *v){ unsigned long flags; arch_spinlock_t *lock = lock_addr(v); s64 val;
local_irq_save(flags); arch_spin_lock(lock); val = v->counter - 1; if (val >= 0) v->counter = val; arch_spin_unlock(lock); local_irq_restore(flags); return val;}EXPORT_SYMBOL(generic_atomic64_dec_if_positive);
s64 generic_atomic64_cmpxchg(atomic64_t *v, s64 o, s64 n){ unsigned long flags; arch_spinlock_t *lock = lock_addr(v); s64 val;
local_irq_save(flags); arch_spin_lock(lock); val = v->counter; if (val == o) v->counter = n; arch_spin_unlock(lock); local_irq_restore(flags); return val;}EXPORT_SYMBOL(generic_atomic64_cmpxchg);
s64 generic_atomic64_xchg(atomic64_t *v, s64 new){ unsigned long flags; arch_spinlock_t *lock = lock_addr(v); s64 val;
local_irq_save(flags); arch_spin_lock(lock); val = v->counter; v->counter = new; arch_spin_unlock(lock); local_irq_restore(flags); return val;}EXPORT_SYMBOL(generic_atomic64_xchg);
s64 generic_atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u){ unsigned long flags; arch_spinlock_t *lock = lock_addr(v); s64 val;
local_irq_save(flags); arch_spin_lock(lock); val = v->counter; if (val != u) v->counter += a; arch_spin_unlock(lock); local_irq_restore(flags);
return val;}EXPORT_SYMBOL(generic_atomic64_fetch_add_unless);