tipc: Prevent loss of fragmented messages over unicast links (b76b27ca) · Commits · 戴 / test

Modifies unicast link endpoint logic so an incoming fragmented message is not lost if reassembly cannot begin because there is no buffer big enough to hold the entire reassembled message. The link endpoint now ignores the first fragment completely, which causes the sending node to retransmit the first fragment so that reassembly can be re-attempted. Previously, the sender would have had no reason to retransmit the 1st fragment, so we would never have a chance to re-try the allocation. Signed-off-by:

Allan Stephens <allan.stephens@windriver.com>

net/tipc/link.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -1774,6 +1774,7 @@ protocol_check:
		head = link_insert_deferred_queue(l_ptr,
		head);
		if (likely(msg_is_dest(msg, tipc_own_addr))) {
		int ret;
		deliver:
		if (likely(msg_isdata(msg))) {
		tipc_node_unlock(n_ptr);
		@@ -1798,11 +1799,15 @@ deliver:
		continue;
		case MSG_FRAGMENTER:
		l_ptr->stats.recv_fragments++;
		if (tipc_link_recv_fragment(&l_ptr->defragm_buf,
		&buf, &msg)) {
		ret = tipc_link_recv_fragment(
		&l_ptr->defragm_buf,
		&buf, &msg);
		if (ret == 1) {
		l_ptr->stats.recv_fragmented++;
		goto deliver;
		}
		if (ret == -1)
		l_ptr->next_in_no--;
		break;
		case CHANGEOVER_PROTOCOL:
		type = msg_type(msg);
		@@ -2632,7 +2637,9 @@ int tipc_link_recv_fragment(struct sk_buff pending, struct sk_buff fb,
		set_fragm_size(pbuf, fragm_sz);
		set_expected_frags(pbuf, exp_fragm_cnt - 1);
		} else {
		warn("Link unable to reassemble fragmented message\n");
		dbg("Link unable to reassemble fragmented message\n");
		buf_discard(fbuf);
		return -1;
		}
		buf_discard(fbuf);
		return 0;

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