[dpdk-dev] [Bug 60] rte_event_port_unlink() causes subsequent events to end up in wrong port

[Elo, Matias (Nokia - FI/Espoo)]

> I think this should handle the unlink case you mention, however perhaps you have identified a genuine bug. If you have more info or a sample config / app that easily demonstrates the issue that would help reproduce/debug here? 


Hi Harry,

The bug report includes a simple test application for demonstrating the issue. I've done some further digging and the following simple patch seems to fix the issue of events ending up in wrong ports.


diff --git a/drivers/event/sw/sw_evdev_scheduler.c b/drivers/event/sw/sw_evdev_scheduler.c
index 8a2c9d4f9..57298345d 100644
--- a/drivers/event/sw/sw_evdev_scheduler.c
+++ b/drivers/event/sw/sw_evdev_scheduler.c
@@ -79,9 +79,11 @@ sw_schedule_atomic_to_cq(struct sw_evdev *sw, struct sw_qid * const qid,
 		int cq = fid->cq;
 
 		if (cq < 0) {
-			uint32_t cq_idx = qid->cq_next_tx++;
-			if (qid->cq_next_tx == qid->cq_num_mapped_cqs)
+			uint32_t cq_idx;
+			if (qid->cq_next_tx >= qid->cq_num_mapped_cqs)
 				qid->cq_next_tx = 0;
+			cq_idx = qid->cq_next_tx++;
+
 			cq = qid->cq_map[cq_idx];
 
 			/* find least used */
@@ -168,9 +170,11 @@ sw_schedule_parallel_to_cq(struct sw_evdev *sw, struct sw_qid * const qid,
 		do {
 			if (++cq_check_count > qid->cq_num_mapped_cqs)
 				goto exit;
-			cq = qid->cq_map[cq_idx];
-			if (++cq_idx == qid->cq_num_mapped_cqs)
+
+			if (cq_idx >= qid->cq_num_mapped_cqs)
 				cq_idx = 0;
+			cq = qid->cq_map[cq_idx++];
+
 		} while (rte_event_ring_free_count(
 				sw->ports[cq].cq_worker_ring) == 0 ||
 				sw->ports[cq].inflights == SW_PORT_HIST_LIST);
@@ -251,6 +255,9 @@ sw_schedule_qid_to_cq(struct sw_evdev *sw)
 		if (iq_num >= SW_IQS_MAX)
 			continue;
 
+		if (qid->cq_num_mapped_cqs == 0)
+			continue;
+
 		uint32_t pkts_done = 0;
 		uint32_t count = iq_ring_count(qid->iq[iq_num]);


However, events from atomic/ordered queues may still end up getting stuck when unlinking (scheduled back to unlinked port). In case of atomic queues the problem seems to be related to (struct sw_fid_t *)fid->cq fields being invalid. With ordered queues events get stuck in reorder buffer.

-Matias