[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>
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 08a8fd1..38943ed 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -16,7 +16,9 @@
#define _REQUEST_SOCK_H
#include <linux/slab.h>
+#include <linux/spinlock.h>
#include <linux/types.h>
+
#include <net/sock.h>
struct request_sock;
@@ -74,4 +76,180 @@
__reqsk_free(req);
}
+extern int sysctl_max_syn_backlog;
+
+/** struct tcp_listen_opt - listen state
+ *
+ * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
+ */
+struct tcp_listen_opt {
+ u8 max_qlen_log;
+ /* 3 bytes hole, try to use */
+ int qlen;
+ int qlen_young;
+ int clock_hand;
+ u32 hash_rnd;
+ struct request_sock *syn_table[0];
+};
+
+/** struct request_sock_queue - queue of request_socks
+ *
+ * @rskq_accept_head - FIFO head of established children
+ * @rskq_accept_tail - FIFO tail of established children
+ * @syn_wait_lock - serializer
+ *
+ * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
+ * lock sock while browsing the listening hash (otherwise it's deadlock prone).
+ *
+ * This lock is acquired in read mode only from listening_get_next() seq_file
+ * op and it's acquired in write mode _only_ from code that is actively
+ * changing rskq_accept_head. All readers that are holding the master sock lock
+ * don't need to grab this lock in read mode too as rskq_accept_head. writes
+ * are always protected from the main sock lock.
+ */
+struct request_sock_queue {
+ struct request_sock *rskq_accept_head;
+ struct request_sock *rskq_accept_tail;
+ rwlock_t syn_wait_lock;
+ struct tcp_listen_opt *listen_opt;
+};
+
+extern int reqsk_queue_alloc(struct request_sock_queue *queue,
+ const int nr_table_entries);
+
+static inline struct tcp_listen_opt *reqsk_queue_yank_listen_sk(struct request_sock_queue *queue)
+{
+ struct tcp_listen_opt *lopt;
+
+ write_lock_bh(&queue->syn_wait_lock);
+ lopt = queue->listen_opt;
+ queue->listen_opt = NULL;
+ write_unlock_bh(&queue->syn_wait_lock);
+
+ return lopt;
+}
+
+static inline void reqsk_queue_destroy(struct request_sock_queue *queue)
+{
+ kfree(reqsk_queue_yank_listen_sk(queue));
+}
+
+static inline struct request_sock *
+ reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
+{
+ struct request_sock *req = queue->rskq_accept_head;
+
+ queue->rskq_accept_head = queue->rskq_accept_head = NULL;
+ return req;
+}
+
+static inline int reqsk_queue_empty(struct request_sock_queue *queue)
+{
+ return queue->rskq_accept_head == NULL;
+}
+
+static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
+ struct request_sock *req,
+ struct request_sock **prev_req)
+{
+ write_lock(&queue->syn_wait_lock);
+ *prev_req = req->dl_next;
+ write_unlock(&queue->syn_wait_lock);
+}
+
+static inline void reqsk_queue_add(struct request_sock_queue *queue,
+ struct request_sock *req,
+ struct sock *parent,
+ struct sock *child)
+{
+ req->sk = child;
+ sk_acceptq_added(parent);
+
+ if (queue->rskq_accept_head == NULL)
+ queue->rskq_accept_head = req;
+ else
+ queue->rskq_accept_tail->dl_next = req;
+
+ queue->rskq_accept_tail = req;
+ req->dl_next = NULL;
+}
+
+static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
+{
+ struct request_sock *req = queue->rskq_accept_head;
+
+ BUG_TRAP(req != NULL);
+
+ queue->rskq_accept_head = req->dl_next;
+ if (queue->rskq_accept_head == NULL)
+ queue->rskq_accept_tail = NULL;
+
+ return req;
+}
+
+static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
+ struct sock *parent)
+{
+ struct request_sock *req = reqsk_queue_remove(queue);
+ struct sock *child = req->sk;
+
+ BUG_TRAP(child != NULL);
+
+ sk_acceptq_removed(parent);
+ __reqsk_free(req);
+ return child;
+}
+
+static inline int reqsk_queue_removed(struct request_sock_queue *queue,
+ struct request_sock *req)
+{
+ struct tcp_listen_opt *lopt = queue->listen_opt;
+
+ if (req->retrans == 0)
+ --lopt->qlen_young;
+
+ return --lopt->qlen;
+}
+
+static inline int reqsk_queue_added(struct request_sock_queue *queue)
+{
+ struct tcp_listen_opt *lopt = queue->listen_opt;
+ const int prev_qlen = lopt->qlen;
+
+ lopt->qlen_young++;
+ lopt->qlen++;
+ return prev_qlen;
+}
+
+static inline int reqsk_queue_len(struct request_sock_queue *queue)
+{
+ return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
+}
+
+static inline int reqsk_queue_len_young(struct request_sock_queue *queue)
+{
+ return queue->listen_opt->qlen_young;
+}
+
+static inline int reqsk_queue_is_full(struct request_sock_queue *queue)
+{
+ return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
+}
+
+static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
+ u32 hash, struct request_sock *req,
+ unsigned timeout)
+{
+ struct tcp_listen_opt *lopt = queue->listen_opt;
+
+ req->expires = jiffies + timeout;
+ req->retrans = 0;
+ req->sk = NULL;
+ req->dl_next = lopt->syn_table[hash];
+
+ write_lock(&queue->syn_wait_lock);
+ lopt->syn_table[hash] = req;
+ write_unlock(&queue->syn_wait_lock);
+}
+
#endif /* _REQUEST_SOCK_H */