X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-defer-static.h;fp=urcu-defer-static.h;h=25137690465fa9c32ef5939be20d1cec3bdd17ad;hp=0000000000000000000000000000000000000000;hb=786ee85b1676d2a1865b2db7120c45bafdf954d6;hpb=983e806feba6adf1dd07318fe97e6e8d2255a626

diff --git a/urcu-defer-static.h b/urcu-defer-static.h
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+#ifndef _URCU_DEFER_STATIC_H
+#define _URCU_DEFER_STATIC_H
+
+/*
+ * urcu-defer-static.h
+ *
+ * Userspace RCU header - memory reclamation.
+ *
+ * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-defer.h for linking
+ * dynamically with the userspace rcu reclamation library.
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
+ *
+ * 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
+ *
+ * IBM's contributions to this file may be relicensed under LGPLv2 or later.
+ */
+
+#include <stdlib.h>
+#include <pthread.h>
+
+#include <compiler.h>
+#include <arch.h>
+
+
+/*
+ * Number of entries in the per-thread defer queue. Must be power of 2.
+ */
+#define DEFER_QUEUE_SIZE	(1 << 12)
+#define DEFER_QUEUE_MASK	(DEFER_QUEUE_SIZE - 1)
+
+/*
+ * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
+ */
+#define _LOAD_SHARED(p)	       ACCESS_ONCE(p)
+
+/*
+ * Load a data from shared memory, doing a cache flush if required.
+ */
+#define LOAD_SHARED(p)			\
+	({				\
+		smp_rmc();		\
+		_LOAD_SHARED(p);	\
+	})
+
+/*
+ * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
+ */
+#define _STORE_SHARED(x, v)	({ ACCESS_ONCE(x) = (v); })
+
+/*
+ * Store v into x, where x is located in shared memory. Performs the required
+ * cache flush after writing. Returns v.
+ */
+#define STORE_SHARED(x, v)		\
+	({				\
+		_STORE_SHARED(x, v);	\
+		smp_wmc();		\
+		(v);			\
+	})
+
+/*
+ * This code section can only be included in LGPL 2.1 compatible source code.
+ * See below for the function call wrappers which can be used in code meant to
+ * be only linked with the Userspace RCU library. This comes with a small
+ * performance degradation on the read-side due to the added function calls.
+ * This is required to permit relinking with newer versions of the library.
+ */
+
+#ifdef DEBUG_RCU
+#define rcu_assert(args...)	assert(args)
+#else
+#define rcu_assert(args...)
+#endif
+
+struct defer_queue {
+	unsigned long head;	/* add element at head */
+	unsigned long tail;	/* next element to remove at tail */
+	void **q;
+};
+
+extern struct defer_queue __thread defer_queue;
+
+extern void rcu_defer_barrier_thread(void);
+
+/*
+ * not signal-safe.
+ */
+static inline void _rcu_defer_queue(void *p)
+{
+	unsigned long head, tail;
+
+	/*
+	 * Head is only modified by ourself. Tail can be modified by reclamation
+	 * thread.
+	 */
+	head = defer_queue.head;
+	tail = LOAD_SHARED(defer_queue.tail);
+
+	/*
+	 * If queue is full, empty it ourself.
+	 */
+	if (unlikely(head - tail >= DEFER_QUEUE_SIZE)) {
+		assert(head - tail == DEFER_QUEUE_SIZE);
+		rcu_defer_barrier_thread();
+		assert(head - LOAD_SHARED(defer_queue.tail) == 0);
+	}
+
+	smp_wmb();	/* Publish new pointer before write q[] */
+	_STORE_SHARED(defer_queue.q[head & DEFER_QUEUE_MASK], p);
+	smp_wmb();	/* Write q[] before head. */
+	STORE_SHARED(defer_queue.head, head + 1);
+}
+
+#endif /* _URCU_DEFER_STATIC_H */