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/*
* BIRD Library -- Read-Copy-Update Basic Operations
*
* (c) 2021 Maria Matejka <mq@jmq.cz>
* (c) 2021 CZ.NIC z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
* Note: all the relevant patents shall be expired.
*/
#ifndef _BIRD_RCU_H_
#define _BIRD_RCU_H_
#include "lib/birdlib.h"
#include "lib/lists.h"
#include <stdatomic.h>
#define RCU_GP_PHASE 0x100000
#define RCU_NEST_MASK 0x0fffff
#define RCU_NEST_CNT 0x000001
extern _Atomic uint rcu_gp_ctl;
struct rcu_thread {
node n;
_Atomic uint ctl;
};
extern _Thread_local struct rcu_thread *this_rcu_thread;
static inline void rcu_read_lock(void)
{
uint cmp = atomic_load_explicit(&this_rcu_thread->ctl, memory_order_acquire);
if (cmp & RCU_NEST_MASK)
atomic_store_explicit(&this_rcu_thread->ctl, cmp + RCU_NEST_CNT, memory_order_relaxed);
else
atomic_store(&this_rcu_thread->ctl, atomic_load_explicit(&rcu_gp_ctl, memory_order_acquire));
}
static inline void rcu_read_unlock(void)
{
atomic_fetch_sub(&this_rcu_thread->ctl, RCU_NEST_CNT);
}
void synchronize_rcu(void);
/* Registering and unregistering a birdloop. To be called from birdloop implementation */
void rcu_thread_start(struct rcu_thread *);
void rcu_thread_stop(struct rcu_thread *);
/* Run this from resource init */
void rcu_init(void);
#endif
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