#include <poll.h>
#include "urcu/wfcqueue.h"
+#include "urcu/wfstack.h"
#include "urcu/map/urcu-qsbr.h"
#define BUILD_QSBR_LIB
#include "urcu/static/urcu-qsbr.h"
#include "urcu/tls-compat.h"
#include "urcu-die.h"
+#include "urcu-wait.h"
/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
#undef _LGPL_SOURCE
static CDS_LIST_HEAD(registry);
+struct gp_waiters_thread {
+ struct cds_wfs_node node;
+ struct urcu_wait wait;
+};
+
+/*
+ * Stack keeping threads awaiting to wait for a grace period. Contains
+ * struct gp_waiters_thread objects.
+ */
+static struct cds_wfs_stack gp_waiters = {
+ .head = CDS_WFS_END,
+ .lock = PTHREAD_MUTEX_INITIALIZER,
+};
+
static void mutex_lock(pthread_mutex_t *mutex)
{
int ret;
NULL, NULL, 0);
}
-static void wait_for_readers(void)
+static void wait_for_readers(struct cds_list_head *input_readers,
+ struct cds_list_head *cur_snap_readers,
+ struct cds_list_head *qsreaders)
{
- CDS_LIST_HEAD(qsreaders);
int wait_loops = 0;
struct rcu_reader *index, *tmp;
* reads them in the opposite order).
*/
cmm_smp_wmb();
- cds_list_for_each_entry(index, ®istry, node) {
+ cds_list_for_each_entry(index, input_readers, node) {
_CMM_STORE_SHARED(index->waiting, 1);
}
/* Write futex before read reader_gp */
cmm_smp_mb();
}
- cds_list_for_each_entry_safe(index, tmp, ®istry, node) {
- if (!rcu_gp_ongoing(&index->ctr))
- cds_list_move(&index->node, &qsreaders);
+ cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
+ switch (rcu_reader_state(&index->ctr)) {
+ case RCU_READER_ACTIVE_CURRENT:
+ if (cur_snap_readers) {
+ cds_list_move(&index->node,
+ cur_snap_readers);
+ break;
+ }
+ /* Fall-through */
+ case RCU_READER_INACTIVE:
+ cds_list_move(&index->node, qsreaders);
+ break;
+ case RCU_READER_ACTIVE_OLD:
+ /*
+ * Old snapshot. Leaving node in
+ * input_readers will make us busy-loop
+ * until the snapshot becomes current or
+ * the reader becomes inactive.
+ */
+ break;
+ }
}
- if (cds_list_empty(®istry)) {
+ if (cds_list_empty(input_readers)) {
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
cmm_smp_mb();
}
}
}
- /* put back the reader list in the registry */
- cds_list_splice(&qsreaders, ®istry);
}
/*
#if (CAA_BITS_PER_LONG < 64)
void synchronize_rcu(void)
{
+ CDS_LIST_HEAD(cur_snap_readers);
+ CDS_LIST_HEAD(qsreaders);
unsigned long was_online;
+ struct gp_waiters_thread gp_waiters_thread;
+ struct cds_wfs_head *gp_waiters_head;
+ struct cds_wfs_node *waiters_iter, *waiters_iter_n;
was_online = URCU_TLS(rcu_reader).ctr;
else
cmm_smp_mb();
+ /*
+ * Add ourself to gp_waiters stack of threads awaiting to wait
+ * for a grace period. Proceed to perform the grace period only
+ * if we are the first thread added into the stack.
+ */
+ cds_wfs_node_init(&gp_waiters_thread.node);
+ urcu_wait_init(&gp_waiters_thread.wait);
+ if (cds_wfs_push(&gp_waiters, &gp_waiters_node) != 0) {
+ /* Not first in stack: will be awakened by another thread. */
+ urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
+ goto gp_end;
+ }
+
mutex_lock(&rcu_gp_lock);
+ /*
+ * Pop all waiters into our local stack head.
+ */
+ gp_waiters_head = __cds_wfs_pop_all(&gp_waiters);
+
if (cds_list_empty(®istry))
goto out;
/*
* Wait for readers to observe original parity or be quiescent.
*/
- wait_for_readers();
+ wait_for_readers(®istry, &cur_snap_readers, &qsreaders);
/*
* Must finish waiting for quiescent state for original parity
/*
* Wait for readers to observe new parity or be quiescent.
*/
- wait_for_readers();
+ wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
+
+ /*
+ * Put quiescent reader list back into registry.
+ */
+ cds_list_splice(&qsreaders, ®istry);
out:
mutex_unlock(&rcu_gp_lock);
+ /* Wake all waiters in our stack head, excluding ourself. */
+ cds_wfs_for_each_blocking_safe(gp_waiters_head, waiters_iter,
+ waiters_iter_n) {
+ struct gp_waiters_thread *wt;
+
+ wt = caa_container_of(waiters_iter,
+ struct gp_waiters_thread, node);
+ if (wt == &gp_waiters_thread)
+ continue;
+ urcu_adaptative_wake_up(&wt->wait);
+ }
+
+gp_end:
/*
* Finish waiting for reader threads before letting the old ptr being
* freed.
#else /* !(CAA_BITS_PER_LONG < 64) */
void synchronize_rcu(void)
{
+ CDS_LIST_HEAD(qsreaders);
unsigned long was_online;
+ struct gp_waiters_thread gp_waiters_thread;
+ struct cds_wfs_head *gp_waiters_head;
+ struct cds_wfs_node *waiters_iter, *waiters_iter_n;
was_online = URCU_TLS(rcu_reader).ctr;
else
cmm_smp_mb();
+ /*
+ * Add ourself to gp_waiters stack of threads awaiting to wait
+ * for a grace period. Proceed to perform the grace period only
+ * if we are the first thread added into the stack.
+ */
+ cds_wfs_node_init(&gp_waiters_thread.node);
+ urcu_wait_init(&gp_waiters_thread.wait);
+ if (cds_wfs_push(&gp_waiters, &gp_waiters_thread.node) != 0) {
+ /* Not first in stack: will be awakened by another thread. */
+ urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
+ goto gp_end;
+ }
+
mutex_lock(&rcu_gp_lock);
+
+ /*
+ * Pop all waiters into our local stack head.
+ */
+ gp_waiters_head = __cds_wfs_pop_all(&gp_waiters);
+
if (cds_list_empty(®istry))
goto out;
/*
* Wait for readers to observe new count of be quiescent.
*/
- wait_for_readers();
+ wait_for_readers(®istry, NULL, &qsreaders);
+
+ /*
+ * Put quiescent reader list back into registry.
+ */
+ cds_list_splice(&qsreaders, ®istry);
out:
mutex_unlock(&rcu_gp_lock);
+ /* Wake all waiters in our stack head, excluding ourself. */
+ cds_wfs_for_each_blocking_safe(gp_waiters_head, waiters_iter,
+ waiters_iter_n) {
+ struct gp_waiters_thread *wt;
+
+ wt = caa_container_of(waiters_iter,
+ struct gp_waiters_thread, node);
+ if (wt == &gp_waiters_thread)
+ continue;
+ urcu_adaptative_wake_up(&wt->wait);
+ }
+
+gp_end:
if (was_online)
rcu_thread_online();
else
projects / urcu.git / blobdiff