[NET] Generalise tcp_listen_opt

This chunks out the accept_queue and tcp_listen_opt code and moves
them to net/core/request_sock.c and include/net/request_sock.h, to
make it useful for other transport protocols, DCCP being the first one
to use it.

Next patches will rename tcp_listen_opt to accept_sock and remove the
inline tcp functions that just call a reqsk_queue_ function.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 48 insertions, 0 deletions

diff --git a/net/core/request_sock.c b/net/core/request_sock.c
new file mode 100644
index 00000000000..1258333ca00
--- /dev/null
+++ b/net/core/request_sock.c
@@ -0,0 +1,48 @@
+/*
+ * NET          Generic infrastructure for Network protocols.
+ *
+ * Authors:     Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *              From code originally in include/net/tcp.h
+ *
+ *              This program is free software; you can redistribute it and/or
+ *              modify it under the terms of the GNU General Public License
+ *              as published by the Free Software Foundation; either version
+ *              2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <net/request_sock.h>
+
+int reqsk_queue_alloc(struct request_sock_queue *queue,
+                      const int nr_table_entries)
+{
+        const int lopt_size = sizeof(struct tcp_listen_opt) +
+                              nr_table_entries * sizeof(struct request_sock *);
+        struct tcp_listen_opt *lopt = kmalloc(lopt_size, GFP_KERNEL);
+
+        if (lopt == NULL)
+                return -ENOMEM;
+
+        memset(lopt, 0, lopt_size);
+
+        for (lopt->max_qlen_log = 6;
+             (1 << lopt->max_qlen_log) < sysctl_max_syn_backlog;
+             lopt->max_qlen_log++);
+
+        get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
+        rwlock_init(&queue->syn_wait_lock);
+        queue->rskq_accept_head = queue->rskq_accept_head = NULL;
+
+        write_lock_bh(&queue->syn_wait_lock);
+        queue->listen_opt = lopt;
+        write_unlock_bh(&queue->syn_wait_lock);
+
+        return 0;
+}
+
+EXPORT_SYMBOL(reqsk_queue_alloc);