1 files changed, 106 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/cxgb4/id_table.c b/drivers/infiniband/hw/cxgb4/id_table.c
new file mode 100644
index 0000000000..e2188b335e
--- /dev/null
+++ b/drivers/infiniband/hw/cxgb4/id_table.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2011 Chelsio Communications.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include <linux/kernel.h>
+#include <linux/random.h>
+#include "iw_cxgb4.h"
+
+#define RANDOM_SKIP 16
+
+/*
+ * Trivial bitmap-based allocator. If the random flag is set, the
+ * allocator is designed to:
+ * - pseudo-randomize the id returned such that it is not trivially predictable.
+ * - avoid reuse of recently used id (at the expense of predictability)
+ */
+u32 c4iw_id_alloc(struct c4iw_id_table *alloc)
+{
+	unsigned long flags;
+	u32 obj;
+
+	spin_lock_irqsave(&alloc->lock, flags);
+
+	obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last);
+	if (obj >= alloc->max)
+		obj = find_first_zero_bit(alloc->table, alloc->max);
+
+	if (obj < alloc->max) {
+		if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
+			alloc->last += get_random_u32_below(RANDOM_SKIP);
+		else
+			alloc->last = obj + 1;
+		if (alloc->last >= alloc->max)
+			alloc->last = 0;
+		__set_bit(obj, alloc->table);
+		obj += alloc->start;
+	} else
+		obj = -1;
+
+	spin_unlock_irqrestore(&alloc->lock, flags);
+	return obj;
+}
+
+void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj)
+{
+	unsigned long flags;
+
+	obj -= alloc->start;
+
+	spin_lock_irqsave(&alloc->lock, flags);
+	__clear_bit(obj, alloc->table);
+	spin_unlock_irqrestore(&alloc->lock, flags);
+}
+
+int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
+			u32 reserved, u32 flags)
+{
+	alloc->start = start;
+	alloc->flags = flags;
+	if (flags & C4IW_ID_TABLE_F_RANDOM)
+		alloc->last = get_random_u32_below(RANDOM_SKIP);
+	else
+		alloc->last = 0;
+	alloc->max = num;
+	spin_lock_init(&alloc->lock);
+	alloc->table = bitmap_zalloc(num, GFP_KERNEL);
+	if (!alloc->table)
+		return -ENOMEM;
+
+	if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY))
+		bitmap_set(alloc->table, 0, reserved);
+
+	return 0;
+}
+
+void c4iw_id_table_free(struct c4iw_id_table *alloc)
+{
+	bitmap_free(alloc->table);
+}