[dpdk-dev] [PATCH] event/sw: remove stale IQ references when reconfigured

[Gage Eads <gage.eads@intel.com>]

This commit fixes a bug in which, when the sw PMD is reconfigured, it would
leave stale IQ chunk pointers in each queue's IQ structure. Now, the PMD
initializes all IQs at eventdev start time and releases all IQ chunk
pointers at eventdev stop time (which has the consequence that any events
in a queue when the eventdev is stopped will be lost). This approach should
be resilient to any reconfiguration done between the stop and start, such
as adding or removing queues.

This commit also fixes two potential issues in iq_chunk.h. iq_init()
now initializes the IQ's count field to 0, and iq_dequeue_burst() sets
iq->head to the appropriate next pointer.

Fixes: 5b5e476e59a4 ("event/sw: use dynamically-sized IQs")
Signed-off-by: Gage Eads <gage.eads@intel.com>
---
 drivers/event/sw/iq_chunk.h | 14 +++++++++-
 drivers/event/sw/sw_evdev.c | 62 ++++++++++++++++++++++++++++++++-------------
 2 files changed, 57 insertions(+), 19 deletions(-)

diff --git a/drivers/event/sw/iq_chunk.h b/drivers/event/sw/iq_chunk.h
index 29f5a35..2fa724c 100644
--- a/drivers/event/sw/iq_chunk.h
+++ b/drivers/event/sw/iq_chunk.h
@@ -73,12 +73,24 @@ iq_free_chunk(struct sw_evdev *sw, struct sw_queue_chunk *chunk)
 }
 
 static __rte_always_inline void
+iq_free_chunk_list(struct sw_evdev *sw, struct sw_queue_chunk *head)
+{
+	while (head) {
+		struct sw_queue_chunk *next;
+		next = head->next;
+		iq_free_chunk(sw, head);
+		head = next;
+	}
+}
+
+static __rte_always_inline void
 iq_init(struct sw_evdev *sw, struct sw_iq *iq)
 {
 	iq->head = iq_alloc_chunk(sw);
 	iq->tail = iq->head;
 	iq->head_idx = 0;
 	iq->tail_idx = 0;
+	iq->count = 0;
 }
 
 static __rte_always_inline void
@@ -154,7 +166,7 @@ iq_dequeue_burst(struct sw_evdev *sw,
 
 done:
 	if (unlikely(index == SW_EVS_PER_Q_CHUNK)) {
-		struct sw_queue_chunk *next = iq->head->next;
+		struct sw_queue_chunk *next = current->next;
 		iq_free_chunk(sw, current);
 		iq->head = next;
 		iq->head_idx = 0;
diff --git a/drivers/event/sw/sw_evdev.c b/drivers/event/sw/sw_evdev.c
index 1ef6340..7430a5d 100644
--- a/drivers/event/sw/sw_evdev.c
+++ b/drivers/event/sw/sw_evdev.c
@@ -245,9 +245,6 @@ qid_init(struct sw_evdev *sw, unsigned int idx, int type,
 	char buf[IQ_ROB_NAMESIZE];
 	struct sw_qid *qid = &sw->qids[idx];
 
-	for (i = 0; i < SW_IQS_MAX; i++)
-		iq_init(sw, &qid->iq[i]);
-
 	/* Initialize the FID structures to no pinning (-1), and zero packets */
 	const struct sw_fid_t fid = {.cq = -1, .pcount = 0};
 	for (i = 0; i < RTE_DIM(qid->fids); i++)
@@ -325,11 +322,6 @@ qid_init(struct sw_evdev *sw, unsigned int idx, int type,
 	return 0;
 
 cleanup:
-	for (i = 0; i < SW_IQS_MAX; i++) {
-		if (qid->iq[i].head)
-			iq_free_chunk(sw, qid->iq[i].head);
-	}
-
 	if (qid->reorder_buffer) {
 		rte_free(qid->reorder_buffer);
 		qid->reorder_buffer = NULL;
@@ -348,13 +340,6 @@ sw_queue_release(struct rte_eventdev *dev, uint8_t id)
 {
 	struct sw_evdev *sw = sw_pmd_priv(dev);
 	struct sw_qid *qid = &sw->qids[id];
-	uint32_t i;
-
-	for (i = 0; i < SW_IQS_MAX; i++) {
-		if (!qid->iq[i].head)
-			continue;
-		iq_free_chunk(sw, qid->iq[i].head);
-	}
 
 	if (qid->type == RTE_SCHED_TYPE_ORDERED) {
 		rte_free(qid->reorder_buffer);
@@ -388,6 +373,41 @@ sw_queue_setup(struct rte_eventdev *dev, uint8_t queue_id,
 }
 
 static void
+sw_init_qid_iqs(struct sw_evdev *sw)
+{
+	int i, j;
+
+	/* Initialize the IQ memory of all configured qids */
+	for (i = 0; i < RTE_EVENT_MAX_QUEUES_PER_DEV; i++) {
+		struct sw_qid *qid = &sw->qids[i];
+
+		if (!qid->initialized)
+			continue;
+
+		for (j = 0; j < SW_IQS_MAX; j++)
+			iq_init(sw, &qid->iq[j]);
+	}
+}
+
+static void
+sw_clean_qid_iqs(struct sw_evdev *sw)
+{
+	int i, j;
+
+	/* Release the IQ memory of all configured qids */
+	for (i = 0; i < RTE_EVENT_MAX_QUEUES_PER_DEV; i++) {
+		struct sw_qid *qid = &sw->qids[i];
+
+		for (j = 0; j < SW_IQS_MAX; j++) {
+			if (!qid->iq[j].head)
+				continue;
+			iq_free_chunk_list(sw, qid->iq[j].head);
+			qid->iq[j].head = NULL;
+		}
+	}
+}
+
+static void
 sw_queue_def_conf(struct rte_eventdev *dev, uint8_t queue_id,
 				 struct rte_event_queue_conf *conf)
 {
@@ -434,7 +454,10 @@ sw_dev_configure(const struct rte_eventdev *dev)
 	num_chunks = ((SW_INFLIGHT_EVENTS_TOTAL/SW_EVS_PER_Q_CHUNK)+1) +
 			sw->qid_count*SW_IQS_MAX*2;
 
-	/* If this is a reconfiguration, free the previous IQ allocation */
+	/* If this is a reconfiguration, free the previous IQ allocation. All
+	 * IQ chunk references were cleaned out of the QIDs in sw_stop(), and
+	 * will be reinitialized in sw_start().
+	 */
 	if (sw->chunks)
 		rte_free(sw->chunks);
 
@@ -667,8 +690,8 @@ sw_start(struct rte_eventdev *dev)
 
 	/* check all queues are configured and mapped to ports*/
 	for (i = 0; i < sw->qid_count; i++)
-		if (sw->qids[i].iq[0].head == NULL ||
-				sw->qids[i].cq_num_mapped_cqs == 0) {
+		if (!sw->qids[i].initialized ||
+		    sw->qids[i].cq_num_mapped_cqs == 0) {
 			SW_LOG_ERR("Queue %d not configured\n", i);
 			return -ENOLINK;
 		}
@@ -689,6 +712,8 @@ sw_start(struct rte_eventdev *dev)
 		}
 	}
 
+	sw_init_qid_iqs(sw);
+
 	if (sw_xstats_init(sw) < 0)
 		return -EINVAL;
 
@@ -702,6 +727,7 @@ static void
 sw_stop(struct rte_eventdev *dev)
 {
 	struct sw_evdev *sw = sw_pmd_priv(dev);
+	sw_clean_qid_iqs(sw);
 	sw_xstats_uninit(sw);
 	sw->started = 0;
 	rte_smp_wmb();
-- 
2.7.4