From: Ido Schimmel <idosch@mellanox.com>
Date: Thu, 20 Feb 2020 09:07:52 +0200
Subject: mlxsw: spectrum_span: Only update mirroring agents if present
Patch-mainline: v5.7-rc1
Git-commit: eb833eec3b4cad9d5ba54d573f88f756e4c5fb84
References: bsc#1176774

In order not to needlessly schedule the work item that updates the
mirroring agents, only schedule it if there are any mirroring agents
present.

This is done by adding an atomic counter that counts the active
mirroring agents.

It is incremented / decremented whenever a mirroring agent is created /
destroyed. It is read before scheduling the work item and in the
devlink-resource occupancy callback.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c |   20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
@@ -19,6 +19,7 @@
 struct mlxsw_sp_span {
 	struct work_struct work;
 	struct mlxsw_sp *mlxsw_sp;
+	atomic_t active_entries_count;
 	int entries_count;
 	struct mlxsw_sp_span_entry entries[0];
 };
@@ -28,15 +29,8 @@ static void mlxsw_sp_span_respin_work(st
 static u64 mlxsw_sp_span_occ_get(void *priv)
 {
 	const struct mlxsw_sp *mlxsw_sp = priv;
-	u64 occ = 0;
-	int i;
 
-	for (i = 0; i < mlxsw_sp->span->entries_count; i++) {
-		if (mlxsw_sp->span->entries[i].ref_count)
-			occ++;
-	}
-
-	return occ;
+	return atomic_read(&mlxsw_sp->span->active_entries_count);
 }
 
 int mlxsw_sp_span_init(struct mlxsw_sp *mlxsw_sp)
@@ -53,6 +47,7 @@ int mlxsw_sp_span_init(struct mlxsw_sp *
 	if (!span)
 		return -ENOMEM;
 	span->entries_count = entries_count;
+	atomic_set(&span->active_entries_count, 0);
 	span->mlxsw_sp = mlxsw_sp;
 	mlxsw_sp->span = span;
 
@@ -668,6 +663,7 @@ mlxsw_sp_span_entry_create(struct mlxsw_
 	if (!span_entry)
 		return NULL;
 
+	atomic_inc(&mlxsw_sp->span->active_entries_count);
 	span_entry->ops = ops;
 	span_entry->ref_count = 1;
 	span_entry->to_dev = to_dev;
@@ -676,9 +672,11 @@ mlxsw_sp_span_entry_create(struct mlxsw_
 	return span_entry;
 }
 
-static void mlxsw_sp_span_entry_destroy(struct mlxsw_sp_span_entry *span_entry)
+static void mlxsw_sp_span_entry_destroy(struct mlxsw_sp *mlxsw_sp,
+					struct mlxsw_sp_span_entry *span_entry)
 {
 	mlxsw_sp_span_entry_deconfigure(span_entry);
+	atomic_dec(&mlxsw_sp->span->active_entries_count);
 }
 
 struct mlxsw_sp_span_entry *
@@ -740,7 +738,7 @@ static int mlxsw_sp_span_entry_put(struc
 {
 	WARN_ON(!span_entry->ref_count);
 	if (--span_entry->ref_count == 0)
-		mlxsw_sp_span_entry_destroy(span_entry);
+		mlxsw_sp_span_entry_destroy(mlxsw_sp, span_entry);
 	return 0;
 }
 
@@ -1033,5 +1031,7 @@ static void mlxsw_sp_span_respin_work(st
 
 void mlxsw_sp_span_respin(struct mlxsw_sp *mlxsw_sp)
 {
+	if (atomic_read(&mlxsw_sp->span->active_entries_count) == 0)
+		return;
 	mlxsw_core_schedule_work(&mlxsw_sp->span->work);
 }