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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Bitan Biswas <bbiswas@nvidia.com>,
        Thierry Reding <treding@nvidia.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.3 049/197] net: stmmac: Avoid deadlock on suspend/resume
Date:   Sun, 27 Oct 2019 21:59:27 +0100
Message-Id: <20191027203354.341058811@linuxfoundation.org>
In-Reply-To: <20191027203351.684916567@linuxfoundation.org>
References: <20191027203351.684916567@linuxfoundation.org>
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From: Thierry Reding <treding@nvidia.com>

[ Upstream commit 134cc4cefad34d8d24670d8a911b59c3b89c6731 ]

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 69cc9133336fc..8d5ec73e02d34 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4454,10 +4454,10 @@ 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);
 
@@ -4471,9 +4471,11 @@ 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);
@@ -4565,6 +4567,8 @@ 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);
@@ -4573,8 +4577,6 @@ int stmmac_resume(struct device *dev)
 
 	phylink_mac_change(priv->phylink, true);
 
-	mutex_unlock(&priv->lock);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(stmmac_resume);
-- 
2.20.1