[PATCH net-next v2 01/11] net: stmmac: ptp: improve handling of aux_ts_lock lifetime

[Russell King (Oracle)]

The aux_ts_lock mutex is only required while the PTP clock has been
successfully registered.

stmmac_ptp_register() does not return any errors (as we don't wish to
prevent the netdev being opened if PTP fails), stmmac_ptp_unregister()
was coded to allow it to be called irrespective of whether PTP was
successfully registered or not.

Arrange for the aux_ts_lock mutex to be destroyed if the PTP clock
is not functional during stmmac_ptp_register(), and only destroy it
in stmmac_ptp_unregister() if we had a PTP clock registered.

Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index 69bd8ace139c..993ff4e87e55 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -370,8 +370,12 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
 	if (IS_ERR(priv->ptp_clock)) {
 		netdev_err(priv->dev, "ptp_clock_register failed\n");
 		priv->ptp_clock = NULL;
-	} else if (priv->ptp_clock)
+	}
+
+	if (priv->ptp_clock)
 		netdev_info(priv->dev, "registered PTP clock\n");
+	else
+		mutex_destroy(&priv->aux_ts_lock);
 }
 
 /**
@@ -387,7 +391,7 @@ void stmmac_ptp_unregister(struct stmmac_priv *priv)
 		priv->ptp_clock = NULL;
 		pr_debug("Removed PTP HW clock successfully on %s\n",
 			 priv->dev->name);
-	}
 
-	mutex_destroy(&priv->aux_ts_lock);
+		mutex_destroy(&priv->aux_ts_lock);
+	}
 }
-- 
2.47.3