#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);
-/*
- * 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;
+ struct urcu_wait wait;
};
/*
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)
* if we are the first thread added into the stack.
*/
cds_wfs_node_init(&gp_waiters_thread.node);
- gp_waiters_thread.wait_futex = AWAKE_WAITING;
+ 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_futex);
+ urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
goto gp_end;
}
struct gp_waiters_thread, node);
if (wt == &gp_waiters_thread)
continue;
- urcu_adaptative_wake_up(&wt->wait_futex);
+ urcu_adaptative_wake_up(&wt->wait);
}
gp_end:
* if we are the first thread added into the stack.
*/
cds_wfs_node_init(&gp_waiters_thread.node);
- gp_waiters_thread.wait_futex = AWAKE_WAITING;
+ 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_futex);
+ urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
goto gp_end;
}
struct gp_waiters_thread, node);
if (wt == &gp_waiters_thread)
continue;
- urcu_adaptative_wake_up(&wt->wait_futex);
+ urcu_adaptative_wake_up(&wt->wait);
}
gp_end:
--- /dev/null
+#ifndef _URCU_WAIT_H
+#define _URCU_WAIT_H
+
+/*
+ * urcu-wait.h
+ *
+ * Userspace RCU library wait/wakeup management
+ *
+ * Copyright (c) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <urcu/uatomic.h>
+
+/*
+ * Number of busy-loop attempts before waiting on futex for grace period
+ * batching.
+ */
+#define URCU_WAIT_ATTEMPTS 1000
+
+enum urcu_wait_state {
+ /* URCU_WAIT_WAITING is compared directly (futex compares it). */
+ URCU_WAIT_WAITING = 0,
+ /* non-zero are used as masks. */
+ URCU_WAIT_WAKEUP = (1 << 0),
+ URCU_WAIT_AWAKENED = (1 << 1),
+ URCU_WAIT_TEARDOWN = (1 << 2),
+};
+
+struct urcu_wait {
+ int32_t futex;
+};
+
+static inline
+void urcu_wait_init(struct urcu_wait *wait)
+{
+ wait->futex = URCU_WAIT_WAITING;
+}
+
+/*
+ * 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
+ * URCU_WAIT_TEARDOWN flag.
+ */
+static inline
+void urcu_adaptative_wake_up(struct urcu_wait *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);
+ /* Allow teardown of struct urcu_wait memory. */
+ uatomic_or(&wait->futex, 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)
+{
+ unsigned int i;
+
+ /* Load and test condition before read futex */
+ cmm_smp_rmb();
+ for (i = 0; i < URCU_WAIT_ATTEMPTS; i++) {
+ if (uatomic_read(&wait->futex) != URCU_WAIT_WAITING)
+ goto skip_futex_wait;
+ caa_cpu_relax();
+ }
+ futex_noasync(&wait->futex, FUTEX_WAIT,
+ URCU_WAIT_WAITING, NULL, NULL, 0);
+skip_futex_wait:
+
+ /* Tell waker thread than we are awakened. */
+ uatomic_or(&wait->futex, URCU_WAIT_AWAKENED);
+
+ /*
+ * 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)
+ break;
+ caa_cpu_relax();
+ }
+ while (!(uatomic_read(&wait->futex) & URCU_WAIT_TEARDOWN))
+ poll(NULL, 0, 10);
+ assert(uatomic_read(&wait->futex) & URCU_WAIT_TEARDOWN);
+}
+
+#endif /* _URCU_WAIT_H */
projects / userspace-rcu.git / commitdiff
