*/
#include <urcu/uatomic.h>
+#include <urcu/wfstack.h>
+#include "urcu-die.h"
/*
* Number of busy-loop attempts before waiting on futex for grace period
URCU_WAIT_WAITING = 0,
/* non-zero are used as masks. */
URCU_WAIT_WAKEUP = (1 << 0),
- URCU_WAIT_AWAKENED = (1 << 1),
+ URCU_WAIT_RUNNING = (1 << 1),
URCU_WAIT_TEARDOWN = (1 << 2),
};
-struct urcu_wait {
- int32_t futex;
+struct urcu_wait_node {
+ struct cds_wfs_node node;
+ int32_t state; /* enum urcu_wait_state */
};
+#define URCU_WAIT_NODE_INIT(name, _state) \
+ { .state = _state }
+
+#define DEFINE_URCU_WAIT_NODE(name, state) \
+ struct urcu_wait_node name = URCU_WAIT_NODE_INIT(name, state)
+
+#define DECLARE_URCU_WAIT_NODE(name) \
+ struct urcu_wait_node name
+
+struct urcu_wait_queue {
+ struct cds_wfs_stack stack;
+};
+
+#define URCU_WAIT_QUEUE_HEAD_INIT(name) \
+ { .stack.head = CDS_WFS_END, .stack.lock = PTHREAD_MUTEX_INITIALIZER }
+
+#define DECLARE_URCU_WAIT_QUEUE(name) \
+ struct urcu_wait_queue name
+
+#define DEFINE_URCU_WAIT_QUEUE(name) \
+ struct urcu_wait_queue name = URCU_WAIT_QUEUE_HEAD_INIT(name)
+
+struct urcu_waiters {
+ struct cds_wfs_head *head;
+};
+
+/*
+ * Add ourself atomically to a wait queue. Return 0 if queue was
+ * previously empty, else return 1.
+ * A full memory barrier is issued before being added to the wait queue.
+ */
static inline
-void urcu_wait_init(struct urcu_wait *wait)
+bool urcu_wait_add(struct urcu_wait_queue *queue,
+ struct urcu_wait_node *node)
{
- wait->futex = URCU_WAIT_WAITING;
+ return cds_wfs_push(&queue->stack, &node->node);
+}
+
+/*
+ * Atomically move all waiters from wait queue into our local struct
+ * urcu_waiters.
+ */
+static inline
+void urcu_move_waiters(struct urcu_waiters *waiters,
+ struct urcu_wait_queue *queue)
+{
+ waiters->head = __cds_wfs_pop_all(&queue->stack);
+}
+
+static inline
+void urcu_wait_set_state(struct urcu_wait_node *node,
+ enum urcu_wait_state state)
+{
+ node->state = state;
+}
+
+static inline
+void urcu_wait_node_init(struct urcu_wait_node *node,
+ enum urcu_wait_state state)
+{
+ urcu_wait_set_state(node, state);
+ cds_wfs_node_init(&node->node);
}
/*
* Note: urcu_adaptative_wake_up needs "value" to stay allocated
- * throughout its execution. In this scheme, the waiter owns the futex
+ * throughout its execution. In this scheme, the waiter owns the node
* memory, and we only allow it to free this memory when it receives the
* URCU_WAIT_TEARDOWN flag.
*/
static inline
-void urcu_adaptative_wake_up(struct urcu_wait *wait)
+void urcu_adaptative_wake_up(struct urcu_wait_node *wait)
{
cmm_smp_mb();
- assert(uatomic_read(&wait->futex) == URCU_WAIT_WAITING);
- uatomic_set(&wait->futex, URCU_WAIT_WAKEUP);
- if (!(uatomic_read(&wait->futex) & URCU_WAIT_AWAKENED))
- futex_noasync(&wait->futex, FUTEX_WAKE, 1, NULL, NULL, 0);
+ assert(uatomic_read(&wait->state) == URCU_WAIT_WAITING);
+ uatomic_set(&wait->state, URCU_WAIT_WAKEUP);
+ if (!(uatomic_read(&wait->state) & URCU_WAIT_RUNNING)) {
+ if (futex_noasync(&wait->state, FUTEX_WAKE, 1,
+ NULL, NULL, 0) < 0)
+ urcu_die(errno);
+ }
/* Allow teardown of struct urcu_wait memory. */
- uatomic_or(&wait->futex, URCU_WAIT_TEARDOWN);
+ uatomic_or(&wait->state, URCU_WAIT_TEARDOWN);
}
/*
* Caller must initialize "value" to URCU_WAIT_WAITING before passing its
* memory to waker thread.
*/
-static void urcu_adaptative_busy_wait(struct urcu_wait *wait)
+static inline
+void urcu_adaptative_busy_wait(struct urcu_wait_node *wait)
{
unsigned int i;
- /* Load and test condition before read futex */
+ /* Load and test condition before read state */
cmm_smp_rmb();
for (i = 0; i < URCU_WAIT_ATTEMPTS; i++) {
- if (uatomic_read(&wait->futex) != URCU_WAIT_WAITING)
+ if (uatomic_read(&wait->state) != URCU_WAIT_WAITING)
goto skip_futex_wait;
caa_cpu_relax();
}
- futex_noasync(&wait->futex, FUTEX_WAIT,
- URCU_WAIT_WAITING, NULL, NULL, 0);
+ while (futex_noasync(&wait->state, FUTEX_WAIT, URCU_WAIT_WAITING,
+ NULL, NULL, 0)) {
+ switch (errno) {
+ case EWOULDBLOCK:
+ /* Value already changed. */
+ goto skip_futex_wait;
+ case EINTR:
+ /* Retry if interrupted by signal. */
+ break; /* Get out of switch. */
+ default:
+ /* Unexpected error. */
+ urcu_die(errno);
+ }
+ }
skip_futex_wait:
- /* Tell waker thread than we are awakened. */
- uatomic_or(&wait->futex, URCU_WAIT_AWAKENED);
+ /* Tell waker thread than we are running. */
+ uatomic_or(&wait->state, URCU_WAIT_RUNNING);
/*
* Wait until waker thread lets us know it's ok to tear down
* memory allocated for struct urcu_wait.
*/
for (i = 0; i < URCU_WAIT_ATTEMPTS; i++) {
- if (uatomic_read(&wait->futex) & URCU_WAIT_TEARDOWN)
+ if (uatomic_read(&wait->state) & URCU_WAIT_TEARDOWN)
break;
caa_cpu_relax();
}
- while (!(uatomic_read(&wait->futex) & URCU_WAIT_TEARDOWN))
+ while (!(uatomic_read(&wait->state) & URCU_WAIT_TEARDOWN))
poll(NULL, 0, 10);
- assert(uatomic_read(&wait->futex) & URCU_WAIT_TEARDOWN);
+ assert(uatomic_read(&wait->state) & URCU_WAIT_TEARDOWN);
+}
+
+static inline
+void urcu_wake_all_waiters(struct urcu_waiters *waiters)
+{
+ struct cds_wfs_node *iter, *iter_n;
+
+ /* Wake all waiters in our stack head */
+ cds_wfs_for_each_blocking_safe(waiters->head, iter, iter_n) {
+ struct urcu_wait_node *wait_node =
+ caa_container_of(iter, struct urcu_wait_node, node);
+
+ /* Don't wake already running threads */
+ if (wait_node->state & URCU_WAIT_RUNNING)
+ continue;
+ urcu_adaptative_wake_up(wait_node);
+ }
}
#endif /* _URCU_WAIT_H */
projects / urcu.git / blobdiff