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When created, AF_UNIX socket is put into net->unx.table.buckets[], and the hash is stored in sk->sk_hash. * unbound socket : 0 <= sk_hash <= UNIX_HASH_MOD When bind() is called, the socket could be moved to another bucket. * pathname socket : 0 <= sk_hash <= UNIX_HASH_MOD * abstract socket : UNIX_HASH_MOD + 1 <= sk_hash <= UNIX_HASH_MOD * 2 + 1 Then, we call unix_table_double_lock() which locks a single bucket or two. Let's define the order as unix_table_lock_cmp_fn() instead of using spin_lock_nested(). The locking is always done in ascending order of sk->sk_hash, which is the index of buckets/locks array allocated by kvmalloc_array(). sk_hash_A < sk_hash_B <=> &locks[sk_hash_A].dep_map < &locks[sk_hash_B].dep_map So, the relation of two sk->sk_hash can be derived from the addresses of dep_map in the array of locks. Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Paolo Abeni <pabeni@redhat.com>