1 files changed, 135 insertions, 0 deletions
diff --git a/runtime/mempool.c b/runtime/mempool.c
new file mode 100644
index 00000000..0fbb4326
--- /dev/null
+++ b/runtime/mempool.c
@@ -0,0 +1,135 @@
+/*  -*- linux-c -*-
+ * Preallocated memory pools
+ * Copyright (C) 2008 Red Hat Inc.
+ *
+ * This file is part of systemtap, and is free software.  You can
+ * redistribute it and/or modify it under the terms of the GNU General
+ * Public License (GPL); either version 2, or (at your option) any
+ * later version.
+ */
+
+#ifndef _STP_MEMPOOL_C_
+#define _STP_MEMPOOL_C_
+
+/* An opaque struct identifying the memory pool. */
+typedef struct {
+	struct list_head free_list;
+	unsigned num;
+	unsigned size;
+	spinlock_t lock;
+} _stp_mempool_t;
+
+/* for internal use only */
+struct _stp_mem_buffer {
+	struct list_head list;
+	_stp_mempool_t *pool;
+	void *buf;
+};
+
+/* Delete a memory pool */
+static void _stp_mempool_destroy(_stp_mempool_t *pool)
+{
+	struct list_head *p, *tmp;
+	if (pool) {
+		list_for_each_safe(p, tmp, &pool->free_list) {
+			list_del(p);
+			_stp_kfree(p);
+		}
+		_stp_kfree(pool);
+	}
+}
+
+/* Create a new memory pool */
+static _stp_mempool_t *_stp_mempool_init(size_t size, size_t num)
+{
+	int i, alloc_size;
+	struct _stp_mem_buffer *m;
+
+	_stp_mempool_t *pool = (_stp_mempool_t *)_stp_kmalloc(sizeof(_stp_mempool_t));
+	if (unlikely(pool == NULL)) {
+		errk("Memory allocation failed.\n");
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&pool->free_list);
+	spin_lock_init(&pool->lock);
+
+	alloc_size = size + sizeof(struct _stp_mem_buffer) - sizeof(void *);
+
+	for (i = 0; i < num; i++) {
+		m = (struct _stp_mem_buffer *)_stp_kmalloc(alloc_size);
+		if (unlikely(m == NULL))
+			goto err;
+		m->pool = pool;
+		list_add((struct list_head *)m, &pool->free_list);
+	}
+	pool->num = num;
+	pool->size = alloc_size;
+	return pool;
+
+err:
+	_stp_mempool_destroy(pool);
+	return NULL;
+}
+
+/* Resize a memory pool */
+static int _stp_mempool_resize(_stp_mempool_t *pool, size_t num)
+{
+	int i;
+	unsigned long flags;
+	struct _stp_mem_buffer *m;
+
+	if (unlikely(num == 0 || num == pool->num))
+		return pool->num;
+
+	if (num > pool->num) {
+		for (i = 0; i < num - pool->num; i++) {
+			m = (struct _stp_mem_buffer *)_stp_kmalloc(pool->size);
+			if (unlikely(m == NULL))
+				goto done;
+			m->pool = pool;
+			pool->num++;
+			spin_lock_irqsave(&pool->lock, flags);
+			list_add((struct list_head *)m, &pool->free_list);
+			spin_unlock_irqrestore(&pool->lock, flags);
+		}
+	} else {
+		for (i = 0; i < pool->num - num; i++) {
+			spin_lock_irqsave(&pool->lock, flags);
+			m = (struct _stp_mem_buffer *)pool->free_list.next;
+			list_del(&m->list);
+			spin_unlock_irqrestore(&pool->lock, flags);
+			_stp_kfree(m);
+		}
+		pool->num = num;
+	}
+done:
+	return num;
+}
+
+/* allocate a buffer from a memory pool */
+static void *_stp_mempool_alloc(_stp_mempool_t *pool)
+{
+	unsigned long flags;
+	struct _stp_mem_buffer *ptr = NULL;
+	spin_lock_irqsave(&pool->lock, flags);
+	if (likely(!list_empty(&pool->free_list))) {
+		ptr = (struct _stp_mem_buffer *)pool->free_list.next;
+		list_del_init(&ptr->list);
+		spin_unlock_irqrestore(&pool->lock, flags);
+		return &ptr->buf;
+	}
+	spin_unlock_irqrestore(&pool->lock, flags);
+	return NULL;
+}
+
+/* return a buffer to its memory pool */
+static void _stp_mempool_free(void *buf)
+{
+	unsigned long flags;
+	struct _stp_mem_buffer *m = container_of(buf, struct _stp_mem_buffer, buf);
+	spin_lock_irqsave(&m->pool->lock, flags);
+	list_add(&m->list, &m->pool->free_list);
+	spin_unlock_irqrestore(&m->pool->lock, flags);
+}
+#endif /* _STP_MEMPOOL_C_ */