tipc: Avoid recomputation of outgoing message length

Rework TIPC's message sending routines to take advantage of the total
amount of data value passed to it by the kernel socket infrastructure.
This change eliminates the need for TIPC to compute the size of outgoing
messages itself, as well as the check for an oversize message in
tipc_msg_build().  In addition, this change warrants an explanation:

   -     res = send_packet(NULL, sock, &my_msg, 0);
   +     res = send_packet(NULL, sock, &my_msg, bytes_to_send);

Previously, the final argument to send_packet() was ignored (since the
amount of data being sent was recalculated by a lower-level routine)
and we could just pass in a dummy value (0). Now that the
recalculation is being eliminated, the argument value being passed to
send_packet() is significant and we have to supply the actual amount
of data we want to send.

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

1 files changed, 3 insertions, 22 deletions

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index 6d92d17e7fb..03e57bf92c7 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -68,20 +68,6 @@ void tipc_msg_init(struct tipc_msg *m, u32 user, u32 type,
 }
 
 /**
- * tipc_msg_calc_data_size - determine total data size for message
- */
-
-int tipc_msg_calc_data_size(struct iovec const *msg_sect, u32 num_sect)
-{
-	int dsz = 0;
-	int i;
-
-	for (i = 0; i < num_sect; i++)
-		dsz += msg_sect[i].iov_len;
-	return dsz;
-}
-
-/**
  * tipc_msg_build - create message using specified header and data
  *
  * Note: Caller must not hold any locks in case copy_from_user() is interrupted!
@@ -89,18 +75,13 @@ int tipc_msg_calc_data_size(struct iovec const *msg_sect, u32 num_sect)
  * Returns message data size or errno
  */
 
-int tipc_msg_build(struct tipc_msg *hdr,
-			    struct iovec const *msg_sect, u32 num_sect,
+int tipc_msg_build(struct tipc_msg *hdr, struct iovec const *msg_sect,
+		   u32 num_sect, unsigned int total_len,
 			    int max_size, int usrmem, struct sk_buff **buf)
 {
 	int dsz, sz, hsz, pos, res, cnt;
 
-	dsz = tipc_msg_calc_data_size(msg_sect, num_sect);
-	if (unlikely(dsz > TIPC_MAX_USER_MSG_SIZE)) {
-		*buf = NULL;
-		return -EINVAL;
-	}
-
+	dsz = total_len;
 	pos = hsz = msg_hdr_sz(hdr);
 	sz = hsz + dsz;
 	msg_set_size(hdr, sz);