[PATCH net-next 09/10] net/mlx5: HWS, rework rehash loop

[Tariq Toukan <tariqt@nvidia.com>]

From: Yevgeny Kliteynik <kliteyn@nvidia.com>

Reworking the rehash loop - simplifying the code and making it less
error prone:
 - Instead of doing round-robin on all the queues with batch of rules in
   each cycle, just go over all the queues and move all the rules that
   belong to this queue.
 - If at some stage of moving the rule we get a failure (which should
   not happen), this can't be rolled back. So instead of aborting
   rehash and leaving the matcher in a broken state, allow the loop
   to continue: attempt to move the rest of the rules and delete the
   old matcher. A rule that failed to move to a new matcher will loose
   its match STE once the rehash is completed and the old matcher is
   deleted, so the rule won't match any traffic any more. This rule's
   packets will fall back to the steering pipeline w/o HW offload.
   Rehash procedure will return an error, which will cause the rule
   insertion to fail for the rule that started this whole rehash.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Vlad Dogaru <vdogaru@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../mellanox/mlx5/core/steering/hws/bwc.c     | 127 +++++++-----------
 1 file changed, 52 insertions(+), 75 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
index 456fac895f5e..9e057f808ea5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
@@ -610,95 +610,69 @@ hws_bwc_matcher_find_at(struct mlx5hws_bwc_matcher *bwc_matcher,
 
 static int hws_bwc_matcher_move_all_simple(struct mlx5hws_bwc_matcher *bwc_matcher)
 {
+	bool move_error = false, poll_error = false, drain_error = false;
 	struct mlx5hws_context *ctx = bwc_matcher->matcher->tbl->ctx;
+	struct mlx5hws_matcher *matcher = bwc_matcher->matcher;
 	u16 bwc_queues = mlx5hws_bwc_queues(ctx);
-	struct mlx5hws_bwc_rule **bwc_rules;
 	struct mlx5hws_rule_attr rule_attr;
-	u32 *pending_rules;
-	int i, j, ret = 0;
-	bool all_done;
-	u16 burst_th;
+	struct mlx5hws_bwc_rule *bwc_rule;
+	struct mlx5hws_send_engine *queue;
+	struct list_head *rules_list;
+	u32 pending_rules;
+	int i, ret = 0;
 
 	mlx5hws_bwc_rule_fill_attr(bwc_matcher, 0, 0, &rule_attr);
 
-	pending_rules = kcalloc(bwc_queues, sizeof(*pending_rules), GFP_KERNEL);
-	if (!pending_rules)
-		return -ENOMEM;
-
-	bwc_rules = kcalloc(bwc_queues, sizeof(*bwc_rules), GFP_KERNEL);
-	if (!bwc_rules) {
-		ret = -ENOMEM;
-		goto free_pending_rules;
-	}
-
 	for (i = 0; i < bwc_queues; i++) {
 		if (list_empty(&bwc_matcher->rules[i]))
-			bwc_rules[i] = NULL;
-		else
-			bwc_rules[i] = list_first_entry(&bwc_matcher->rules[i],
-							struct mlx5hws_bwc_rule,
-							list_node);
-	}
+			continue;
 
-	do {
-		all_done = true;
+		pending_rules = 0;
+		rule_attr.queue_id = mlx5hws_bwc_get_queue_id(ctx, i);
+		rules_list = &bwc_matcher->rules[i];
 
-		for (i = 0; i < bwc_queues; i++) {
-			rule_attr.queue_id = mlx5hws_bwc_get_queue_id(ctx, i);
-			burst_th = hws_bwc_get_burst_th(ctx, rule_attr.queue_id);
-
-			for (j = 0; j < burst_th && bwc_rules[i]; j++) {
-				rule_attr.burst = !!((j + 1) % burst_th);
-				ret = mlx5hws_matcher_resize_rule_move(bwc_matcher->matcher,
-								       bwc_rules[i]->rule,
-								       &rule_attr);
-				if (unlikely(ret)) {
-					mlx5hws_err(ctx,
-						    "Moving BWC rule failed during rehash (%d)\n",
-						    ret);
-					goto free_bwc_rules;
-				}
+		list_for_each_entry(bwc_rule, rules_list, list_node) {
+			ret = mlx5hws_matcher_resize_rule_move(matcher,
+							       bwc_rule->rule,
+							       &rule_attr);
+			if (unlikely(ret && !move_error)) {
+				mlx5hws_err(ctx,
+					    "Moving BWC rule: move failed (%d), attempting to move rest of the rules\n",
+					    ret);
+				move_error = true;
+			}
 
-				all_done = false;
-				pending_rules[i]++;
-				bwc_rules[i] = list_is_last(&bwc_rules[i]->list_node,
-							    &bwc_matcher->rules[i]) ?
-					       NULL : list_next_entry(bwc_rules[i], list_node);
-
-				ret = mlx5hws_bwc_queue_poll(ctx,
-							     rule_attr.queue_id,
-							     &pending_rules[i],
-							     false);
-				if (unlikely(ret)) {
-					mlx5hws_err(ctx,
-						    "Moving BWC rule failed during rehash (%d)\n",
-						    ret);
-					goto free_bwc_rules;
-				}
+			pending_rules++;
+			ret = mlx5hws_bwc_queue_poll(ctx,
+						     rule_attr.queue_id,
+						     &pending_rules,
+						     false);
+			if (unlikely(ret && !poll_error)) {
+				mlx5hws_err(ctx,
+					    "Moving BWC rule: poll failed (%d), attempting to move rest of the rules\n",
+					    ret);
+				poll_error = true;
 			}
 		}
-	} while (!all_done);
-
-	/* drain all the bwc queues */
-	for (i = 0; i < bwc_queues; i++) {
-		if (pending_rules[i]) {
-			u16 queue_id = mlx5hws_bwc_get_queue_id(ctx, i);
 
-			mlx5hws_send_engine_flush_queue(&ctx->send_queue[queue_id]);
-			ret = mlx5hws_bwc_queue_poll(ctx, queue_id,
-						     &pending_rules[i], true);
-			if (unlikely(ret)) {
+		if (pending_rules) {
+			queue = &ctx->send_queue[rule_attr.queue_id];
+			mlx5hws_send_engine_flush_queue(queue);
+			ret = mlx5hws_bwc_queue_poll(ctx,
+						     rule_attr.queue_id,
+						     &pending_rules,
+						     true);
+			if (unlikely(ret && !drain_error)) {
 				mlx5hws_err(ctx,
-					    "Moving BWC rule failed during rehash (%d)\n", ret);
-				goto free_bwc_rules;
+					    "Moving BWC rule: drain failed (%d), attempting to move rest of the rules\n",
+					    ret);
+				drain_error = true;
 			}
 		}
 	}
 
-free_bwc_rules:
-	kfree(bwc_rules);
-free_pending_rules:
-	kfree(pending_rules);
+	if (move_error || poll_error || drain_error)
+		ret = -EINVAL;
 
 	return ret;
 }
@@ -742,15 +716,18 @@ static int hws_bwc_matcher_move(struct mlx5hws_bwc_matcher *bwc_matcher)
 	}
 
 	ret = hws_bwc_matcher_move_all(bwc_matcher);
-	if (ret) {
-		mlx5hws_err(ctx, "Rehash error: moving rules failed\n");
-		return -ENOMEM;
-	}
+	if (ret)
+		mlx5hws_err(ctx, "Rehash error: moving rules failed, attempting to remove the old matcher\n");
+
+	/* Error during rehash can't be rolled back.
+	 * The best option here is to allow the rehash to complete and remove
+	 * the old matcher - can't leave the matcher in the 'in_resize' state.
+	 */
 
 	bwc_matcher->matcher = new_matcher;
 	mlx5hws_matcher_destroy(old_matcher);
 
-	return 0;
+	return ret;
 }
 
 static int
-- 
2.31.1