[PATCH net] net: stmmac: Hold rtnl lock in suspend/resume callbacks

[Jose Abreu]

We need to hold rnl lock in suspend and resume callbacks because phylink
requires it. Otherwise we will get a WARN() in suspend and resume.

Also, move phylink start and stop callbacks to inside device's internal
lock so that we prevent concurrent HW accesses.

Fixes: 74371272f97f ("net: stmmac: Convert to phylink and remove phylib logic")
Reported-by: Christophe ROULLIER <christophe.roullier@xxxxxx>
Tested-by: Christophe ROULLIER <christophe.roullier@xxxxxx>
Signed-off-by: Jose Abreu <joabreu@xxxxxxxxxxxx>

---
Cc: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>
Cc: Alexandre Torgue <alexandre.torgue@xxxxxx>
Cc: Jose Abreu <joabreu@xxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Christophe ROULLIER <christophe.roullier@xxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index fd54c7c87485..b19ab09cb18f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4451,10 +4451,12 @@ int stmmac_suspend(struct device *dev)
 	if (!ndev || !netif_running(ndev))
 		return 0;
 
-	phylink_stop(priv->phylink);
-
 	mutex_lock(&priv->lock);
 
+	rtnl_lock();
+	phylink_stop(priv->phylink);
+	rtnl_unlock();
+
 	netif_device_detach(ndev);
 	stmmac_stop_all_queues(priv);
 
@@ -4558,9 +4560,11 @@ int stmmac_resume(struct device *dev)
 
 	stmmac_start_all_queues(priv);
 
-	mutex_unlock(&priv->lock);
-
+	rtnl_lock();
 	phylink_start(priv->phylink);
+	rtnl_unlock();
+
+	mutex_unlock(&priv->lock);
 
 	return 0;
 }
-- 
2.7.4