[PATCH v2 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.

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

---

v2:
- Rework fix to simpler suggestion (Bruce)
- Respin patchset to "apply order" (Bruce)

---
 drivers/event/sw/sw_evdev_scheduler.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/event/sw/sw_evdev_scheduler.c b/drivers/event/sw/sw_evdev_scheduler.c
index de6ed21643..21c360770e 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 +164,13 @@ 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;
+		const uint32_t fid = SW_HASH_FLOWID(qe->flow_id);
+		p->hist_list[head] = (struct sw_hist_list_entry) {
+			.qid = qid_id,
+			.fid = fid,
+		};
+
+
 
 		if (keep_order)
 			rob_ring_dequeue(qid->reorder_buffer_freelist,
-- 
2.34.1