Re: [RFC 1/4] hashtable: introduce a small and naive hashtable

[Sasha Levin <levinsasha928@xxxxxxxxx>]

On 08/02/2012 01:23 PM, Sasha Levin wrote:
>> #define DEFINE_HASH_TABLE(name, length) struct hash_table name = { .count = length, .buckets = { [0 ... (length - 1)] = HLIST_HEAD_INIT } }
> The limitation of this approach is that the struct hash_table variable must be 'static', which is a bit limiting - see for example the use of hashtable in 'struct user_namespace'.
> 

What if we just use two possible decelerations? One of static structs and one for regular ones.

struct hash_table {
        size_t bits;
        struct hlist_head buckets[];
};

#define DEFINE_HASHTABLE(name, bits)                                    \
        union {                                                         \
                struct hash_table name;                                 \
                struct {                                                \
                        size_t bits;                                    \
                        struct hlist_head buckets[1 << bits];           \
                } __name;                                               \
        }

#define DEFINE_STATIC_HASHTABLE(name, bit)                              \
        static struct hash_table name = { .bits = bit,                  \
                .buckets = { [0 ... (bit - 1)] = HLIST_HEAD_INIT } }

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