net/mlx5: HWS, force rehash when rule insertion failed

Rules are inserted into hash table in accordance with their hash index.
When a certain number of rules is reached, the table is rehashed:
a bigger new table is allocated and all the rules are moved there.
But sometimes a new rule can't be inserted into the hash table
because its index is full, even though the number of rules in the
table is well below the threshold. The hash function is not perfect,
so such cases are not rare. When that happens, we want to do the same
rehash, in order to increase the table size and lower the probability
for such cases.

This patch fixes the usecase where rule insertion was failing, but
rehash couldn't be initiated due to low number of rules: it adds flag
that denotes that rehash is required, even if the number of rules in
the table is below the rehash threshold.

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>
Link: https://patch.msgid.link/1746992290-568936-7-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 d70db6948dbb2f2bc079d9efe6e0b577a691ac52..dce2605fc99bae23f569025b17f25ab8bcdf3042 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.c
@@ -169,6 +169,7 @@ mlx5hws_bwc_matcher_create(struct mlx5hws_table *table,
                return NULL;
 
        atomic_set(&bwc_matcher->num_of_rules, 0);
+       atomic_set(&bwc_matcher->rehash_required, false);
 
        /* Check if the required match params can be all matched
         * in single STE, otherwise complex matcher is needed.
@@ -769,9 +770,9 @@ hws_bwc_matcher_rehash_size(struct mlx5hws_bwc_matcher *bwc_matcher)
 
        /* It is possible that other rule has already performed rehash.
         * Need to check again if we really need rehash.
-        * If the reason for rehash was size, but not any more - skip rehash.
         */
-       if (!hws_bwc_matcher_rehash_size_needed(bwc_matcher,
+       if (!atomic_read(&bwc_matcher->rehash_required) &&
+           !hws_bwc_matcher_rehash_size_needed(bwc_matcher,
                                                atomic_read(&bwc_matcher->num_of_rules)))
                return 0;
 
@@ -782,6 +783,8 @@ hws_bwc_matcher_rehash_size(struct mlx5hws_bwc_matcher *bwc_matcher)
         *  - destroy the old matcher
         */
 
+       atomic_set(&bwc_matcher->rehash_required, false);
+
        ret = hws_bwc_matcher_extend_size(bwc_matcher);
        if (ret)
                return ret;
@@ -875,6 +878,7 @@ int mlx5hws_bwc_rule_create_simple(struct mlx5hws_bwc_rule *bwc_rule,
         * Try rehash by size and insert rule again - last chance.
         */
 
+       atomic_set(&bwc_matcher->rehash_required, true);
        mutex_unlock(queue_lock);
 
        hws_bwc_lock_all_queues(ctx);

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.h b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.h
index cf2b651463179269470f8636081705c4eff67ef2..d21fc247a510dc86e22eb948323fb7125b01a16c 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/bwc.h
@@ -30,6 +30,7 @@ struct mlx5hws_bwc_matcher {
        u8 size_log;
        u32 priority;
        atomic_t num_of_rules;
+       atomic_t rehash_required;
        struct list_head *rules;
 };