mirror of
https://gitlab.nic.cz/labs/bird.git
synced 2024-12-23 10:11:53 +00:00
80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
/*
|
|
* 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.
|
|
*
|
|
* Using the Supplementary Material for User-Level Implementations of Read-Copy-Update
|
|
* by Matthieu Desnoyers, Paul E. McKenney, Alan S. Stern, Michel R. Dagenais and Jonathan Walpole
|
|
* obtained from https://www.efficios.com/pub/rcu/urcu-supp-accepted.pdf
|
|
*/
|
|
|
|
#include "lib/rcu.h"
|
|
#include "lib/io-loop.h"
|
|
#include "lib/locking.h"
|
|
|
|
_Atomic uint rcu_gp_ctl = RCU_NEST_CNT;
|
|
_Thread_local struct rcu_thread *this_rcu_thread = NULL;
|
|
|
|
static list rcu_thread_list;
|
|
|
|
static struct rcu_thread main_rcu_thread;
|
|
|
|
static DOMAIN(resource) rcu_domain;
|
|
|
|
static int
|
|
rcu_gp_ongoing(_Atomic uint *ctl)
|
|
{
|
|
uint val = atomic_load(ctl);
|
|
return (val & RCU_NEST_CNT) && ((val ^ rcu_gp_ctl) & RCU_GP_PHASE);
|
|
}
|
|
|
|
static void
|
|
update_counter_and_wait(void)
|
|
{
|
|
atomic_fetch_xor(&rcu_gp_ctl, RCU_GP_PHASE);
|
|
struct rcu_thread *rc;
|
|
WALK_LIST(rc, rcu_thread_list)
|
|
while (rcu_gp_ongoing(&rc->ctl))
|
|
birdloop_yield();
|
|
}
|
|
|
|
void
|
|
synchronize_rcu(void)
|
|
{
|
|
LOCK_DOMAIN(resource, rcu_domain);
|
|
update_counter_and_wait();
|
|
update_counter_and_wait();
|
|
UNLOCK_DOMAIN(resource, rcu_domain);
|
|
}
|
|
|
|
void
|
|
rcu_thread_start(struct rcu_thread *rc)
|
|
{
|
|
LOCK_DOMAIN(resource, rcu_domain);
|
|
add_tail(&rcu_thread_list, &rc->n);
|
|
this_rcu_thread = rc;
|
|
UNLOCK_DOMAIN(resource, rcu_domain);
|
|
}
|
|
|
|
void
|
|
rcu_thread_stop(struct rcu_thread *rc)
|
|
{
|
|
LOCK_DOMAIN(resource, rcu_domain);
|
|
this_rcu_thread = NULL;
|
|
rem_node(&rc->n);
|
|
UNLOCK_DOMAIN(resource, rcu_domain);
|
|
}
|
|
|
|
void
|
|
rcu_init(void)
|
|
{
|
|
rcu_domain = DOMAIN_NEW(resource);
|
|
DOMAIN_SETUP(resource, rcu_domain, "Read-Copy-Update", NULL);
|
|
init_list(&rcu_thread_list);
|
|
rcu_thread_start(&main_rcu_thread);
|
|
}
|