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2b38a833cd
Explicitly marking domains eligible for RCU synchronization. It's then forbidden to lock these domains in RCU critical section to avoid possible deadlock.
62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*
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* BIRD Library -- Read-Copy-Update Basic Operations
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*
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* (c) 2021 Maria Matejka <mq@jmq.cz>
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* (c) 2021 CZ.NIC z.s.p.o.
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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* Note: all the relevant patents shall be expired.
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*/
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#ifndef _BIRD_RCU_H_
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#define _BIRD_RCU_H_
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#include "lib/birdlib.h"
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#include "lib/lists.h"
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#include <stdatomic.h>
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#define RCU_GP_PHASE 0x100000
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#define RCU_NEST_MASK 0x0fffff
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#define RCU_NEST_CNT 0x000001
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extern _Atomic uint rcu_gp_ctl;
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struct rcu_thread {
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node n;
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_Atomic uint ctl;
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};
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extern _Thread_local struct rcu_thread *this_rcu_thread;
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extern _Thread_local uint rcu_blocked;
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static inline void rcu_read_lock(void)
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{
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uint cmp = atomic_load_explicit(&this_rcu_thread->ctl, memory_order_acquire);
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if (cmp & RCU_NEST_MASK)
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atomic_store_explicit(&this_rcu_thread->ctl, cmp + RCU_NEST_CNT, memory_order_relaxed);
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else
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atomic_store(&this_rcu_thread->ctl, atomic_load_explicit(&rcu_gp_ctl, memory_order_acquire));
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}
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static inline void rcu_read_unlock(void)
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{
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atomic_fetch_sub(&this_rcu_thread->ctl, RCU_NEST_CNT);
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}
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static inline _Bool rcu_read_active(void)
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{
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return !!(atomic_load_explicit(&this_rcu_thread->ctl, memory_order_acquire) & RCU_NEST_MASK);
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}
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void synchronize_rcu(void);
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/* Registering and unregistering a birdloop. To be called from birdloop implementation */
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void rcu_thread_start(struct rcu_thread *);
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void rcu_thread_stop(struct rcu_thread *);
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/* Run this from resource init */
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void rcu_init(void);
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#endif
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