net/mlx5: HWS, fix redundant extension of action templates

When a rule is inserted into a matcher, we search for the suitable
action template. If such template is not found, action template array
is extended with the new template. However, when several threads are
performing this in parallel, there is a race - we can end up with
extending the action templates array with the same template.

This patch is doing the following:
 - refactor the code to find action template index in rule create and
   update, have the common code in an auxiliary function
 - after locking all the queues, check again if the action template
   array still needs to be extended

Signed-off-by: Vlad Dogaru <vdogaru@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1746992290-568936-9-git-send-email-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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 7d991a61eeb39073afb54794b034498033f026de..456fac895f5eff97f41e1633b36ff52c8454443b 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
@@ -789,6 +789,53 @@ hws_bwc_matcher_rehash_size(struct mlx5hws_bwc_matcher *bwc_matcher)
        return hws_bwc_matcher_move(bwc_matcher);
 }
 
+static int hws_bwc_rule_get_at_idx(struct mlx5hws_bwc_rule *bwc_rule,
+                                  struct mlx5hws_rule_action rule_actions[],
+                                  u16 bwc_queue_idx)
+{
+       struct mlx5hws_bwc_matcher *bwc_matcher = bwc_rule->bwc_matcher;
+       struct mlx5hws_context *ctx = bwc_matcher->matcher->tbl->ctx;
+       struct mutex *queue_lock; /* Protect the queue */
+       int at_idx, ret;
+
+       /* check if rehash needed due to missing action template */
+       at_idx = hws_bwc_matcher_find_at(bwc_matcher, rule_actions);
+       if (likely(at_idx >= 0))
+               return at_idx;
+
+       /* we need to extend BWC matcher action templates array */
+       queue_lock = hws_bwc_get_queue_lock(ctx, bwc_queue_idx);
+       mutex_unlock(queue_lock);
+       hws_bwc_lock_all_queues(ctx);
+
+       /* check again - perhaps other thread already did extend_at */
+       at_idx = hws_bwc_matcher_find_at(bwc_matcher, rule_actions);
+       if (at_idx >= 0)
+               goto out;
+
+       ret = hws_bwc_matcher_extend_at(bwc_matcher, rule_actions);
+       if (unlikely(ret)) {
+               mlx5hws_err(ctx, "BWC rule: failed extending AT (%d)", ret);
+               at_idx = -EINVAL;
+               goto out;
+       }
+
+       /* action templates array was extended, we need the last idx */
+       at_idx = bwc_matcher->num_of_at - 1;
+       ret = mlx5hws_matcher_attach_at(bwc_matcher->matcher,
+                                       bwc_matcher->at[at_idx]);
+       if (unlikely(ret)) {
+               mlx5hws_err(ctx, "BWC rule: failed attaching new AT (%d)", ret);
+               at_idx = -EINVAL;
+               goto out;
+       }
+
+out:
+       hws_bwc_unlock_all_queues(ctx);
+       mutex_lock(queue_lock);
+       return at_idx;
+}
+
 int mlx5hws_bwc_rule_create_simple(struct mlx5hws_bwc_rule *bwc_rule,
                                   u32 *match_param,
                                   struct mlx5hws_rule_action rule_actions[],
@@ -809,31 +856,12 @@ int mlx5hws_bwc_rule_create_simple(struct mlx5hws_bwc_rule *bwc_rule,
 
        mutex_lock(queue_lock);
 
-       /* check if rehash needed due to missing action template */
-       at_idx = hws_bwc_matcher_find_at(bwc_matcher, rule_actions);
+       at_idx = hws_bwc_rule_get_at_idx(bwc_rule, rule_actions, bwc_queue_idx);
        if (unlikely(at_idx < 0)) {
-               /* we need to extend BWC matcher action templates array */
                mutex_unlock(queue_lock);
-               hws_bwc_lock_all_queues(ctx);
-
-               ret = hws_bwc_matcher_extend_at(bwc_matcher, rule_actions);
-               if (unlikely(ret)) {
-                       hws_bwc_unlock_all_queues(ctx);
-                       return ret;
-               }
-
-               /* action templates array was extended, we need the last idx */
-               at_idx = bwc_matcher->num_of_at - 1;
-
-               ret = mlx5hws_matcher_attach_at(bwc_matcher->matcher,
-                                               bwc_matcher->at[at_idx]);
-               if (unlikely(ret)) {
-                       hws_bwc_unlock_all_queues(ctx);
-                       return ret;
-               }
-
-               hws_bwc_unlock_all_queues(ctx);
-               mutex_lock(queue_lock);
+               mlx5hws_err(ctx, "BWC rule create: failed getting AT (%d)",
+                           ret);
+               return -EINVAL;
        }
 
        /* check if number of rules require rehash */
@@ -971,36 +999,11 @@ hws_bwc_rule_action_update(struct mlx5hws_bwc_rule *bwc_rule,
 
        mutex_lock(queue_lock);
 
-       /* check if rehash needed due to missing action template */
-       at_idx = hws_bwc_matcher_find_at(bwc_matcher, rule_actions);
+       at_idx = hws_bwc_rule_get_at_idx(bwc_rule, rule_actions, idx);
        if (unlikely(at_idx < 0)) {
-               /* we need to extend BWC matcher action templates array */
                mutex_unlock(queue_lock);
-               hws_bwc_lock_all_queues(ctx);
-
-               /* check again - perhaps other thread already did extend_at */
-               at_idx = hws_bwc_matcher_find_at(bwc_matcher, rule_actions);
-               if (likely(at_idx < 0)) {
-                       ret = hws_bwc_matcher_extend_at(bwc_matcher, rule_actions);
-                       if (unlikely(ret)) {
-                               hws_bwc_unlock_all_queues(ctx);
-                               mlx5hws_err(ctx, "BWC rule update: failed extending AT (%d)", ret);
-                               return -EINVAL;
-                       }
-
-                       /* action templates array was extended, we need the last idx */
-                       at_idx = bwc_matcher->num_of_at - 1;
-
-                       ret = mlx5hws_matcher_attach_at(bwc_matcher->matcher,
-                                                       bwc_matcher->at[at_idx]);
-                       if (unlikely(ret)) {
-                               hws_bwc_unlock_all_queues(ctx);
-                               return ret;
-                       }
-               }
-
-               hws_bwc_unlock_all_queues(ctx);
-               mutex_lock(queue_lock);
+               mlx5hws_err(ctx, "BWC rule update: failed getting AT\n");
+               return -EINVAL;
        }
 
        ret = hws_bwc_rule_update_sync(bwc_rule,