[TFRC]: Migrate TX history to singly-linked lis

This patch was based on another made by Gerrit Renker, his changelog was:

    ------------------------------------------------------
The patch set migrates TFRC TX history to a singly-linked list.

The details are:
 * use of a consistent naming scheme (all TFRC functions now begin with `tfrc_');
 * allocation and cleanup are taken care of internally;
 * provision of a lookup function, which is used by the CCID TX infrastructure
   to determine the time a packet was sent (in turn used for RTT sampling);
 * integration of the new interface with the present use in CCID3.
    ------------------------------------------------------

Simplifications I did:

. removing the tfrc_tx_hist_head that had a pointer to the list head and
  another for the slabcache.
. No need for creating a slabcache for each CCID that wants to use the TFRC
  tx history routines, create a single slabcache when the dccp_tfrc_lib module
  init routine is called.

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

1 files changed, 15 insertions, 64 deletions

diff --git a/net/dccp/ccids/lib/packet_history.h b/net/dccp/ccids/lib/packet_history.h
index 032bb61c6e39..5c07182dd659 100644
--- a/net/dccp/ccids/lib/packet_history.h
+++ b/net/dccp/ccids/lib/packet_history.h
@@ -1,10 +1,9 @@
 /*
- *  net/dccp/packet_history.h
+ *  Packet RX/TX history data structures and routines for TFRC-based protocols.
  *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
  *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
  *
- *  An implementation of the DCCP protocol
- *
  *  This code has been developed by the University of Waikato WAND
  *  research group. For further information please see http://www.wand.net.nz/
  *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
@@ -49,71 +48,23 @@
 #define TFRC_WIN_COUNT_PER_RTT	 4
 #define TFRC_WIN_COUNT_LIMIT	16
 
-/*
- * 	Transmitter History data structures and declarations
+/**
+ *  tfrc_tx_hist_entry  -  Simple singly-linked TX history list
+ *  @next:  next oldest entry (LIFO order)
+ *  @seqno: sequence number of this entry
+ *  @stamp: send time of packet with sequence number @seqno
  */
-struct dccp_tx_hist_entry {
-	struct list_head dccphtx_node;
-	u64		 dccphtx_seqno:48,
-			 dccphtx_sent:1;
-	u32		 dccphtx_rtt;
-	ktime_t		 dccphtx_tstamp;
-};
-
-struct dccp_tx_hist {
-	struct kmem_cache *dccptxh_slab;
+struct tfrc_tx_hist_entry {
+	struct tfrc_tx_hist_entry *next;
+	u64			  seqno;
+	ktime_t			  stamp;
 };
 
-extern struct dccp_tx_hist *dccp_tx_hist_new(const char *name);
-extern void 		    dccp_tx_hist_delete(struct dccp_tx_hist *hist);
-
-static inline struct dccp_tx_hist_entry *
-			dccp_tx_hist_entry_new(struct dccp_tx_hist *hist,
-					       const gfp_t prio)
-{
-	struct dccp_tx_hist_entry *entry = kmem_cache_alloc(hist->dccptxh_slab,
-							    prio);
-
-	if (entry != NULL)
-		entry->dccphtx_sent = 0;
-
-	return entry;
-}
-
-static inline struct dccp_tx_hist_entry *
-			dccp_tx_hist_head(struct list_head *list)
-{
-	struct dccp_tx_hist_entry *head = NULL;
-
-	if (!list_empty(list))
-		head = list_entry(list->next, struct dccp_tx_hist_entry,
-				  dccphtx_node);
-	return head;
-}
-
-extern struct dccp_tx_hist_entry *
-			dccp_tx_hist_find_entry(const struct list_head *list,
-						const u64 seq);
-
-static inline void dccp_tx_hist_add_entry(struct list_head *list,
-					  struct dccp_tx_hist_entry *entry)
-{
-	list_add(&entry->dccphtx_node, list);
-}
-
-static inline void dccp_tx_hist_entry_delete(struct dccp_tx_hist *hist,
-					     struct dccp_tx_hist_entry *entry)
-{
-	if (entry != NULL)
-		kmem_cache_free(hist->dccptxh_slab, entry);
-}
-
-extern void dccp_tx_hist_purge(struct dccp_tx_hist *hist,
-			       struct list_head *list);
+extern int  tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
+extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
 
-extern void dccp_tx_hist_purge_older(struct dccp_tx_hist *hist,
-				     struct list_head *list,
-				     struct dccp_tx_hist_entry *next);
+extern struct tfrc_tx_hist_entry *
+	tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 ackno);
 
 /*
  * 	Receiver History data structures and declarations