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Subject[PATCH net] net: stmmac: Avoid deadlock on suspend/resume
Date
From: Thierry Reding <treding@nvidia.com>

The stmmac driver will try to acquire its private mutex during suspend
via phylink_resolve() -> stmmac_mac_link_down() -> stmmac_eee_init().
However, the phylink configuration is updated with the private mutex
held already, which causes a deadlock during suspend.

Fix this by moving the phylink configuration updates out of the region
of code protected by the private mutex.

Fixes: 19e13cb27b99 ("net: stmmac: Hold rtnl lock in suspend/resume callbacks")
Suggested-by: Bitan Biswas <bbiswas@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 843d53e084b7..c76a1336a451 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4716,10 +4716,10 @@ int stmmac_suspend(struct device *dev)
if (!ndev || !netif_running(ndev))
return 0;

- mutex_lock(&priv->lock);
-
phylink_mac_change(priv->phylink, false);

+ mutex_lock(&priv->lock);
+
netif_device_detach(ndev);
stmmac_stop_all_queues(priv);

@@ -4733,9 +4733,11 @@ int stmmac_suspend(struct device *dev)
stmmac_pmt(priv, priv->hw, priv->wolopts);
priv->irq_wake = 1;
} else {
+ mutex_unlock(&priv->lock);
rtnl_lock();
phylink_stop(priv->phylink);
rtnl_unlock();
+ mutex_lock(&priv->lock);

stmmac_mac_set(priv, priv->ioaddr, false);
pinctrl_pm_select_sleep_state(priv->device);
@@ -4827,6 +4829,8 @@ int stmmac_resume(struct device *dev)

stmmac_start_all_queues(priv);

+ mutex_unlock(&priv->lock);
+
if (!device_may_wakeup(priv->device)) {
rtnl_lock();
phylink_start(priv->phylink);
@@ -4835,8 +4839,6 @@ int stmmac_resume(struct device *dev)

phylink_mac_change(priv->phylink, true);

- mutex_unlock(&priv->lock);
-
return 0;
}
EXPORT_SYMBOL_GPL(stmmac_resume);
--
2.23.0
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