1 files changed, 59 insertions, 0 deletions

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index f48e5857210f..e6d49cdc61b4 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -244,6 +244,65 @@ bool tipc_msg_validate(struct sk_buff **_skb)
 }
 
 /**
+ * tipc_msg_fragment - build a fragment skb list for TIPC message
+ *
+ * @skb: TIPC message skb
+ * @hdr: internal msg header to be put on the top of the fragments
+ * @pktmax: max size of a fragment incl. the header
+ * @frags: returned fragment skb list
+ *
+ * Returns 0 if the fragmentation is successful, otherwise: -EINVAL
+ * or -ENOMEM
+ */
+int tipc_msg_fragment(struct sk_buff *skb, const struct tipc_msg *hdr,
+                      int pktmax, struct sk_buff_head *frags)
+{
+        int pktno, nof_fragms, dsz, dmax, eat;
+        struct tipc_msg *_hdr;
+        struct sk_buff *_skb;
+        u8 *data;
+
+        /* Non-linear buffer? */
+        if (skb_linearize(skb))
+                return -ENOMEM;
+
+        data = (u8 *)skb->data;
+        dsz = msg_size(buf_msg(skb));
+        dmax = pktmax - INT_H_SIZE;
+        if (dsz <= dmax || !dmax)
+                return -EINVAL;
+
+        nof_fragms = dsz / dmax + 1;
+        for (pktno = 1; pktno <= nof_fragms; pktno++) {
+                if (pktno < nof_fragms)
+                        eat = dmax;
+                else
+                        eat = dsz % dmax;
+                /* Allocate a new fragment */
+                _skb = tipc_buf_acquire(INT_H_SIZE + eat, GFP_ATOMIC);
+                if (!_skb)
+                        goto error;
+                skb_orphan(_skb);
+                __skb_queue_tail(frags, _skb);
+                /* Copy header & data to the fragment */
+                skb_copy_to_linear_data(_skb, hdr, INT_H_SIZE);
+                skb_copy_to_linear_data_offset(_skb, INT_H_SIZE, data, eat);
+                data += eat;
+                /* Update the fragment's header */
+                _hdr = buf_msg(_skb);
+                msg_set_fragm_no(_hdr, pktno);
+                msg_set_nof_fragms(_hdr, nof_fragms);
+                msg_set_size(_hdr, INT_H_SIZE + eat);
+        }
+        return 0;
+
+error:
+        __skb_queue_purge(frags);
+        __skb_queue_head_init(frags);
+        return -ENOMEM;
+}
+
+/**
  * tipc_msg_build - create buffer chain containing specified header and data
  * @mhdr: Message header, to be prepended to data
  * @m: User message