tipc: improve the link deferred queue insertion algorithm

Re-code the algorithm for inserting an out-of-sequence message into
a unicast or broadcast link's deferred message queue.  It remains
functionally equivalent but should be easier to understand/maintain.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 23 insertions, 25 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index ac1832a66f8a..c317abf74a78 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1853,17 +1853,16 @@ cont:
 }
 
 /*
- * link_defer_buf(): Sort a received out-of-sequence packet
- *                   into the deferred reception queue.
- * Returns the increase of the queue length,i.e. 0 or 1
+ * tipc_link_defer_pkt - Add out-of-sequence message to deferred reception queue
+ *
+ * Returns increase in queue length (i.e. 0 or 1)
  */
 
-u32 tipc_link_defer_pkt(struct sk_buff **head,
-                        struct sk_buff **tail,
+u32 tipc_link_defer_pkt(struct sk_buff **head, struct sk_buff **tail,
                         struct sk_buff *buf)
 {
-        struct sk_buff *prev = NULL;
-        struct sk_buff *crs = *head;
+        struct sk_buff *queue_buf;
+        struct sk_buff **prev;
         u32 seq_no = buf_seqno(buf);
 
         buf->next = NULL;
@@ -1881,31 +1880,30 @@ u32 tipc_link_defer_pkt(struct sk_buff **head,
                 return 1;
         }
 
-        /* Scan through queue and sort it in */
-        do {
-                struct tipc_msg *msg = buf_msg(crs);
+        /* Locate insertion point in queue, then insert; discard if duplicate */
+        prev = head;
+        queue_buf = *head;
+        for (;;) {
+                u32 curr_seqno = buf_seqno(queue_buf);
 
-                if (less(seq_no, msg_seqno(msg))) {
-                        buf->next = crs;
-                        if (prev)
-                                prev->next = buf;
-                        else
-                                *head = buf;
-                        return 1;
+                if (seq_no == curr_seqno) {
+                        buf_discard(buf);
+                        return 0;
                 }
-                if (seq_no == msg_seqno(msg))
+
+                if (less(seq_no, curr_seqno))
                         break;
-                prev = crs;
-                crs = crs->next;
-        } while (crs);
 
-        /* Message is a duplicate of an existing message */
+                prev = &queue_buf->next;
+                queue_buf = queue_buf->next;
+        }
 
-        buf_discard(buf);
-        return 0;
+        buf->next = queue_buf;
+        *prev = buf;
+        return 1;
 }
 
-/**
+/*
  * link_handle_out_of_seq_msg - handle arrival of out-of-sequence packet
  */