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