/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COOKIE_H
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#define __LINUX_COOKIE_H
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#include <linux/atomic.h>
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#include <linux/percpu.h>
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#include <asm/local.h>
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struct pcpu_gen_cookie {
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local_t nesting;
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u64 last;
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} __aligned(16);
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struct gen_cookie {
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struct pcpu_gen_cookie __percpu *local;
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atomic64_t forward_last ____cacheline_aligned_in_smp;
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atomic64_t reverse_last;
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};
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#define COOKIE_LOCAL_BATCH 4096
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#define DEFINE_COOKIE(name) \
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static DEFINE_PER_CPU(struct pcpu_gen_cookie, __##name); \
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static struct gen_cookie name = { \
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.local = &__##name, \
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.forward_last = ATOMIC64_INIT(0), \
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.reverse_last = ATOMIC64_INIT(0), \
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}
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static __always_inline u64 gen_cookie_next(struct gen_cookie *gc)
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{
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struct pcpu_gen_cookie *local = this_cpu_ptr(gc->local);
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u64 val;
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if (likely(local_inc_return(&local->nesting) == 1)) {
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val = local->last;
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if (__is_defined(CONFIG_SMP) &&
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unlikely((val & (COOKIE_LOCAL_BATCH - 1)) == 0)) {
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s64 next = atomic64_add_return(COOKIE_LOCAL_BATCH,
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&gc->forward_last);
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val = next - COOKIE_LOCAL_BATCH;
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}
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local->last = ++val;
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} else {
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val = atomic64_dec_return(&gc->reverse_last);
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}
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local_dec(&local->nesting);
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return val;
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}
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#endif /* __LINUX_COOKIE_H */
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