netdev - [PATCH net-next 4/9] mlxsw: spectrum_span: On policer_id_base_ref_count, use dec_and

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Date:   Mon,  3 Aug 2020 19:11:36 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, jiri@...lanox.com,
        petrm@...lanox.com, amitc@...lanox.com, mlxsw@...lanox.com,
        Ido Schimmel <idosch@...lanox.com>
Subject: [PATCH net-next 4/9] mlxsw: spectrum_span: On policer_id_base_ref_count, use dec_and_test

From: Petr Machata <petrm@...lanox.com>

When unsetting policer base, the SPAN code currently uses refcount_dec().
However that function splats when the counter reaches zero, because
reaching zero without actually testing is in general indicative of a
missing cleanup. There is no cleanup to be done here, but nonetheless, use
refcount_dec_and_test() as required.

Signed-off-by: Petr Machata <petrm@...lanox.com>
Reviewed-by: Jiri Pirko <jiri@...lanox.com>
Signed-off-by: Ido Schimmel <idosch@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
index 323eaf979aea..5c959a995199 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
@@ -837,7 +837,8 @@ static int mlxsw_sp_span_policer_id_base_set(struct mlxsw_sp_span *span,
 
 static void mlxsw_sp_span_policer_id_base_unset(struct mlxsw_sp_span *span)
 {
-	refcount_dec(&span->policer_id_base_ref_count);
+	if (refcount_dec_and_test(&span->policer_id_base_ref_count))
+		span->policer_id_base = 0;
 }
 
 static struct mlxsw_sp_span_entry *
-- 
2.26.2