#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
void __attribute__((destructor)) rcu_exit(void);
static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
-
-int32_t rcu_gp_futex;
-
-/*
- * Global grace period counter.
- */
-unsigned long rcu_gp_ctr = RCU_GP_ONLINE;
+struct rcu_gp rcu_gp = { .ctr = RCU_GP_ONLINE };
/*
* Active attempts to check for reader Q.S. before calling futex().
static CDS_LIST_HEAD(registry);
/*
- * Number of busy-loop attempts before waiting on futex for grace period
- * batching.
- */
-#define RCU_AWAKE_ATTEMPTS 1000
-
-enum adapt_wakeup_state {
- /* AWAKE_WAITING is compared directly (futex compares it). */
- AWAKE_WAITING = 0,
- /* non-zero are used as masks. */
- AWAKE_WAKEUP = (1 << 0),
- AWAKE_AWAKENED = (1 << 1),
- AWAKE_TEARDOWN = (1 << 2),
-};
-
-struct gp_waiters_thread {
- struct cds_wfs_node node;
- int32_t wait_futex;
-};
-
-/*
- * Stack keeping threads awaiting to wait for a grace period. Contains
+ * Queue 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 DEFINE_URCU_WAIT_QUEUE(gp_waiters);
static void mutex_lock(pthread_mutex_t *mutex)
{
{
/* Read reader_gp before read futex */
cmm_smp_rmb();
- if (uatomic_read(&rcu_gp_futex) == -1)
- futex_noasync(&rcu_gp_futex, FUTEX_WAIT, -1,
+ if (uatomic_read(&rcu_gp.futex) == -1)
+ futex_noasync(&rcu_gp.futex, FUTEX_WAIT, -1,
NULL, NULL, 0);
}
-/*
- * Note: urcu_adaptative_wake_up needs "value" to stay allocated
- * throughout its execution. In this scheme, the waiter owns the futex
- * memory, and we only allow it to free this memory when it receives the
- * AWAKE_TEARDOWN flag.
- */
-static void urcu_adaptative_wake_up(int32_t *value)
-{
- cmm_smp_mb();
- assert(uatomic_read(value) == AWAKE_WAITING);
- uatomic_set(value, AWAKE_WAKEUP);
- if (!(uatomic_read(value) & AWAKE_AWAKENED))
- futex_noasync(value, FUTEX_WAKE, 1, NULL, NULL, 0);
- /* Allow teardown of "value" memory. */
- uatomic_or(value, AWAKE_TEARDOWN);
-}
-
-/*
- * Caller must initialize "value" to AWAKE_WAITING before passing its
- * memory to waker thread.
- */
-static void urcu_adaptative_busy_wait(int32_t *value)
-{
- unsigned int i;
-
- /* Load and test condition before read futex */
- cmm_smp_rmb();
- for (i = 0; i < RCU_AWAKE_ATTEMPTS; i++) {
- if (uatomic_read(value) != AWAKE_WAITING)
- goto skip_futex_wait;
- caa_cpu_relax();
- }
- futex_noasync(value, FUTEX_WAIT, AWAKE_WAITING, NULL, NULL, 0);
-skip_futex_wait:
-
- /* Tell waker thread than we are awakened. */
- uatomic_or(value, AWAKE_AWAKENED);
-
- /*
- * Wait until waker thread lets us know it's ok to tear down
- * memory allocated for value.
- */
- for (i = 0; i < RCU_AWAKE_ATTEMPTS; i++) {
- if (uatomic_read(value) & AWAKE_TEARDOWN)
- break;
- caa_cpu_relax();
- }
- while (!(uatomic_read(value) & AWAKE_TEARDOWN))
- poll(NULL, 0, 10);
- assert(uatomic_read(value) & AWAKE_TEARDOWN);
-}
-
static void wait_for_readers(struct cds_list_head *input_readers,
struct cds_list_head *cur_snap_readers,
struct cds_list_head *qsreaders)
/*
* Wait for each thread URCU_TLS(rcu_reader).ctr to either
* indicate quiescence (offline), or for them to observe the
- * current rcu_gp_ctr value.
+ * current rcu_gp.ctr value.
*/
for (;;) {
wait_loops++;
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
- uatomic_set(&rcu_gp_futex, -1);
+ uatomic_set(&rcu_gp.futex, -1);
/*
* Write futex before write waiting (the other side
* reads them in the opposite order).
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
cmm_smp_mb();
- uatomic_set(&rcu_gp_futex, 0);
+ uatomic_set(&rcu_gp.futex, 0);
}
break;
} else {
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;
+ DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
+ struct urcu_waiters waiters;
- was_online = URCU_TLS(rcu_reader).ctr;
+ was_online = rcu_read_ongoing();
/* All threads should read qparity before accessing data structure
* where new ptr points to. In the "then" case, rcu_thread_offline
cmm_smp_mb();
/*
- * Add ourself to gp_waiters stack of threads awaiting to wait
+ * Add ourself to gp_waiters queue 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.
+ * if we are the first thread added into the queue.
*/
- cds_wfs_node_init(&gp_waiters_thread.node);
- gp_waiters_thread.wait_futex = AWAKE_WAITING;
- 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_futex);
+ if (urcu_wait_add(&gp_waiters, &wait) != 0) {
+ /* Not first in queue: will be awakened by another thread. */
+ urcu_adaptative_busy_wait(&wait);
goto gp_end;
}
+ /* We won't need to wake ourself up */
+ urcu_wait_set_state(&wait, URCU_WAIT_RUNNING);
mutex_lock(&rcu_gp_lock);
/*
- * Pop all waiters into our local stack head.
+ * Move all waiters into our local queue.
*/
- gp_waiters_head = __cds_wfs_pop_all(&gp_waiters);
+ urcu_move_waiters(&waiters, &gp_waiters);
if (cds_list_empty(®istry))
goto out;
/*
* Must finish waiting for quiescent state for original parity
- * before committing next rcu_gp_ctr update to memory. Failure
+ * before committing next rcu_gp.ctr update to memory. Failure
* to do so could result in the writer waiting forever while new
* readers are always accessing data (no progress). Enforce
* compiler-order of load URCU_TLS(rcu_reader).ctr before store
- * to rcu_gp_ctr.
+ * to rcu_gp.ctr.
*/
cmm_barrier();
cmm_smp_mb();
/* Switch parity: 0 -> 1, 1 -> 0 */
- CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR);
+ CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR);
/*
- * Must commit rcu_gp_ctr update to memory before waiting for
+ * Must commit rcu_gp.ctr update to memory before waiting for
* quiescent state. Failure to do so could result in the writer
* waiting forever while new readers are always accessing data
- * (no progress). Enforce compiler-order of store to rcu_gp_ctr
+ * (no progress). Enforce compiler-order of store to rcu_gp.ctr
* before load URCU_TLS(rcu_reader).ctr.
*/
cmm_barrier();
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_futex);
- }
-
+ urcu_wake_all_waiters(&waiters);
gp_end:
/*
* Finish waiting for reader threads before letting the old ptr being
{
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;
+ DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
+ struct urcu_waiters waiters;
- was_online = URCU_TLS(rcu_reader).ctr;
+ was_online = rcu_read_ongoing();
/*
* Mark the writer thread offline to make sure we don't wait for
cmm_smp_mb();
/*
- * Add ourself to gp_waiters stack of threads awaiting to wait
+ * Add ourself to gp_waiters queue 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.
+ * if we are the first thread added into the queue.
*/
- cds_wfs_node_init(&gp_waiters_thread.node);
- gp_waiters_thread.wait_futex = AWAKE_WAITING;
- 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_futex);
+ if (urcu_wait_add(&gp_waiters, &wait) != 0) {
+ /* Not first in queue: will be awakened by another thread. */
+ urcu_adaptative_busy_wait(&wait);
goto gp_end;
}
+ /* We won't need to wake ourself up */
+ urcu_wait_set_state(&wait, URCU_WAIT_RUNNING);
mutex_lock(&rcu_gp_lock);
/*
- * Pop all waiters into our local stack head.
+ * Move all waiters into our local queue.
*/
- gp_waiters_head = __cds_wfs_pop_all(&gp_waiters);
+ urcu_move_waiters(&waiters, &gp_waiters);
if (cds_list_empty(®istry))
goto out;
/* Increment current G.P. */
- CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR);
+ CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr + RCU_GP_CTR);
/*
- * Must commit rcu_gp_ctr update to memory before waiting for
+ * Must commit rcu_gp.ctr update to memory before waiting for
* quiescent state. Failure to do so could result in the writer
* waiting forever while new readers are always accessing data
- * (no progress). Enforce compiler-order of store to rcu_gp_ctr
+ * (no progress). Enforce compiler-order of store to rcu_gp.ctr
* before load URCU_TLS(rcu_reader).ctr.
*/
cmm_barrier();
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_futex);
- }
-
+ urcu_wake_all_waiters(&waiters);
gp_end:
if (was_online)
rcu_thread_online();
_rcu_read_unlock();
}
+int rcu_read_ongoing(void)
+{
+ return _rcu_read_ongoing();
+}
+
void rcu_quiescent_state(void)
{
_rcu_quiescent_state();
projects / urcu.git / blobdiff