This hashtable implementation is using hlist buckets to provide a simple
hashtable to prevent it from getting reimplemented all over the kernel.

Signed-off-by: Sasha Levin <levinsasha...@gmail.com>
---
 include/linux/hashtable.h |   46 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 46 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/hashtable.h

diff --git a/include/linux/hashtable.h b/include/linux/hashtable.h
new file mode 100644
index 0000000..9b29fd1
--- /dev/null
+++ b/include/linux/hashtable.h
@@ -0,0 +1,46 @@
+#ifndef _LINUX_HASHTABLE_H
+#define _LINUX_HASHTABLE_H
+
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/hash.h>
+
+#define DEFINE_HASHTABLE(name, bits)                                   \
+       struct hlist_head name[1 << bits];
+
+#define HASH_BITS(name) (order_base_2(ARRAY_SIZE(name)))
+#define HASH_SIZE(name) (1 << (HASH_BITS(name)))
+
+#define HASH_INIT(name)                                                        
\
+({                                                                     \
+       int __i;                                                        \
+       for (__i = 0 ; __i < HASH_SIZE(name) ; __i++)                   \
+               INIT_HLIST_HEAD(&name[__i]);                            \
+})
+
+#define HASH_ADD(name, obj, key)                                       \
+       hlist_add_head(obj, &name[                                      \
+               hash_long((unsigned long)key, HASH_BITS(name))]);
+
+#define HASH_GET(name, key, type, member, cmp_fn)                      \
+({                                                                     \
+       struct hlist_node *__node;                                      \
+       typeof(key) __key = key;                                        \
+       type *__obj = NULL;                                             \
+       hlist_for_each_entry(__obj, __node, &name[                      \
+                       hash_long((unsigned long) __key,                \
+                       HASH_BITS(name))], member)                      \
+               if (cmp_fn(__obj, __key))                               \
+                       break;                                          \
+       __obj;                                                          \
+})
+
+#define HASH_DEL(obj, member)                                          \
+       hlist_del(&obj->member)
+
+#define HASH_FOR_EACH(bkt, node, name, obj, member)                    \
+       for (bkt = 0; bkt < HASH_SIZE(name); bkt++)                     \
+               hlist_for_each_entry(obj, node, &name[i], member)
+
+#endif
-- 
1.7.8.6

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