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-rw-r--r--net/tipc/msg.c51
1 files changed, 44 insertions, 7 deletions
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index b0d07b35909d..55d8ba92291d 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -251,20 +251,23 @@ bool tipc_msg_validate(struct sk_buff **_skb)
* @pktmax: Max packet size that can be used
* @list: Buffer or chain of buffers to be returned to caller
*
+ * Note that the recursive call we are making here is safe, since it can
+ * logically go only one further level down.
+ *
* Returns message data size or errno: -ENOMEM, -EFAULT
*/
-int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
- int offset, int dsz, int pktmax, struct sk_buff_head *list)
+int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m, int offset,
+ int dsz, int pktmax, struct sk_buff_head *list)
{
int mhsz = msg_hdr_sz(mhdr);
+ struct tipc_msg pkthdr;
int msz = mhsz + dsz;
- int pktno = 1;
- int pktsz;
int pktrem = pktmax;
- int drem = dsz;
- struct tipc_msg pkthdr;
struct sk_buff *skb;
+ int drem = dsz;
+ int pktno = 1;
char *pktpos;
+ int pktsz;
int rc;
msg_set_size(mhdr, msz);
@@ -272,8 +275,18 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
/* No fragmentation needed? */
if (likely(msz <= pktmax)) {
skb = tipc_buf_acquire(msz, GFP_KERNEL);
- if (unlikely(!skb))
+
+ /* Fall back to smaller MTU if node local message */
+ if (unlikely(!skb)) {
+ if (pktmax != MAX_MSG_SIZE)
+ return -ENOMEM;
+ rc = tipc_msg_build(mhdr, m, offset, dsz, FB_MTU, list);
+ if (rc != dsz)
+ return rc;
+ if (tipc_msg_assemble(list))
+ return dsz;
return -ENOMEM;
+ }
skb_orphan(skb);
__skb_queue_tail(list, skb);
skb_copy_to_linear_data(skb, mhdr, mhsz);
@@ -589,6 +602,30 @@ bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
return true;
}
+/* tipc_msg_assemble() - assemble chain of fragments into one message
+ */
+bool tipc_msg_assemble(struct sk_buff_head *list)
+{
+ struct sk_buff *skb, *tmp = NULL;
+
+ if (skb_queue_len(list) == 1)
+ return true;
+
+ while ((skb = __skb_dequeue(list))) {
+ skb->next = NULL;
+ if (tipc_buf_append(&tmp, &skb)) {
+ __skb_queue_tail(list, skb);
+ return true;
+ }
+ if (!tmp)
+ break;
+ }
+ __skb_queue_purge(list);
+ __skb_queue_head_init(list);
+ pr_warn("Failed do assemble buffer\n");
+ return false;
+}
+
/* tipc_msg_reassemble() - clone a buffer chain of fragments and
* reassemble the clones into one message
*/