Trace attempts to process all the recirculations. However, if there
is a recirculation loop, i.e. if every recirculation generates another
recirculation, this process will never stop. It will grind until the
trace fills the system memory.
A simple reproducer:
make sandbox
ovs-vsctl add-br br0
ovs-vsctl add-port br0 p1
ovs-ofctl add-flow br0 "table=0,in_port=p1,ip,actions=ct(table=0)"
ovs-appctl ofproto/trace br0 in_port=p1,ip
Limit the number of recirculations trace is processing with a fairly
arbitrary number - 4096 (loosely based on the resubmit limit, but
they are not actually related).
Not adding a test for this since it's only for a trace, but also
because the test may lead to OOM event in a system if the test fails,
which is not nice.
Fixes: e6bc8e749381 ("ofproto/trace: Add support for tracing conntrack
recirculation")
Reported-by: Jaime Caamaño Ruiz <jcaam...@redhat.com>
Signed-off-by: Ilya Maximets <i.maxim...@ovn.org>
---
ofproto/ofproto-dpif-trace.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/ofproto/ofproto-dpif-trace.c b/ofproto/ofproto-dpif-trace.c
index b86e7fe07..87506aa78 100644
--- a/ofproto/ofproto-dpif-trace.c
+++ b/ofproto/ofproto-dpif-trace.c
@@ -845,17 +845,35 @@ ofproto_trace(struct ofproto_dpif *ofproto, const struct
flow *flow,
bool names)
{
struct ovs_list recirc_queue = OVS_LIST_INITIALIZER(&recirc_queue);
+ int recirculations = 0;
+
ofproto_trace__(ofproto, flow, packet, &recirc_queue,
ofpacts, ofpacts_len, output, names);
struct oftrace_recirc_node *recirc_node;
LIST_FOR_EACH_POP (recirc_node, node, &recirc_queue) {
+ if (recirculations++ > 4096) {
+ ds_put_cstr(output, "\n\n");
+ ds_put_char_multiple(output, '=', 79);
+ ds_put_cstr(output, "\nTrace reached the recirculation limit."
+ " Sopping the trace here.");
+ ds_put_format(output,
+ "\nQueued but not processed: %"PRIuSIZE
+ " recirculations.",
+ ovs_list_size(&recirc_queue) + 1);
+ oftrace_recirc_node_destroy(recirc_node);
+ break;
+ }
ofproto_trace_recirc_node(recirc_node, next_ct_states, output);
ofproto_trace__(ofproto, &recirc_node->flow, recirc_node->packet,
&recirc_queue, ofpacts, ofpacts_len, output,
names);
oftrace_recirc_node_destroy(recirc_node);
}
+ /* Destroy remaining recirculation nodes, if any. */
+ LIST_FOR_EACH_POP (recirc_node, node, &recirc_queue) {
+ oftrace_recirc_node_destroy(recirc_node);
+ }
}
void
--
2.43.0
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