[PATCH v3 1/2] event/sw: fix ordering corruption with op release

[Harry van Haaren]

This commit changes the logic in the scheduler to always
reset reorder-buffer (and QID/FID) entries when writing
them. This avoids stale ROB/QID/FID data re-use, which
previously caused ordering issues.

Before this commit, release events left the history-list
in an inconsistent state, and future events with op type of
forward could be incorrectly reordered.

There was a partial fix previously committed which is now
being resolved for all cases in a more general way, hence
the two fixlines here.

Fixes: 2e516d18dc01 ("event/sw: fix events mis-identified as needing reorder")
Fixes: 617995dfc5b2 ("event/sw: add scheduling logic")
Cc: stable at dpdk.org

Suggested-by: Bruce Richardson <bruce.richardson at intel.com>
Signed-off-by: Harry van Haaren <harry.van.haaren at intel.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>

---

v3:
- Fixup whitespace and line wrapping suggestions (Bruce)
- Add Fixes lines (Bruce)
- Cc stable, as this is a functionality bugfix
- Including Ack from v2, as no significant code changes

v2:
- Rework fix to simpler suggestion (Bruce)
- Respin patchset to "apply order" (Bruce)
---
 drivers/event/sw/sw_evdev_scheduler.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/event/sw/sw_evdev_scheduler.c b/drivers/event/sw/sw_evdev_scheduler.c
index de6ed21643..cc652815e4 100644
--- a/drivers/event/sw/sw_evdev_scheduler.c
+++ b/drivers/event/sw/sw_evdev_scheduler.c
@@ -90,8 +90,10 @@ sw_schedule_atomic_to_cq(struct sw_evdev *sw, struct sw_qid * const qid,
 		sw->cq_ring_space[cq]--;
 
 		int head = (p->hist_head++ & (SW_PORT_HIST_LIST-1));
-		p->hist_list[head].fid = flow_id;
-		p->hist_list[head].qid = qid_id;
+		p->hist_list[head] = (struct sw_hist_list_entry) {
+			.qid = qid_id,
+			.fid = flow_id,
+		};
 
 		p->stats.tx_pkts++;
 		qid->stats.tx_pkts++;
@@ -162,8 +164,10 @@ sw_schedule_parallel_to_cq(struct sw_evdev *sw, struct sw_qid * const qid,
 		qid->stats.tx_pkts++;
 
 		const int head = (p->hist_head & (SW_PORT_HIST_LIST-1));
-		p->hist_list[head].fid = SW_HASH_FLOWID(qe->flow_id);
-		p->hist_list[head].qid = qid_id;
+		p->hist_list[head] = (struct sw_hist_list_entry) {
+			.qid = qid_id,
+			.fid = SW_HASH_FLOWID(qe->flow_id),
+		};
 
 		if (keep_order)
 			rob_ring_dequeue(qid->reorder_buffer_freelist,
@@ -419,7 +423,6 @@ __pull_port_lb(struct sw_evdev *sw, uint32_t port_id, int allow_reorder)
 				struct reorder_buffer_entry *rob_entry =
 						hist_entry->rob_entry;
 
-				hist_entry->rob_entry = NULL;
 				/* Although fragmentation not currently
 				 * supported by eventdev API, we support it
 				 * here. Open: How do we alert the user that
-- 
2.34.1