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From:   Wong Vee Khee <vee.khee.wong@intel.com>
To:     Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc:     netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Ong Boon Leong <boon.leong.ong@intel.com>,
        Voon Wei Feng <weifeng.voon@intel.com>,
        Wong Vee Khee <vee.khee.wong@intel.com>,
        Christophe ROULLIER <christophe.roullier@st.com>
Subject: [PATCH v2 net 1/1] net: stmmac: Use rtnl_lock/unlock on netif_set_real_num_rx_queues() call
Date:   Sun, 15 Nov 2020 15:42:10 +0800
Message-Id: <20201115074210.23605-1-vee.khee.wong@intel.com>
Precedence: bulk

Fix an issue where dump stack is printed on suspend resume flow due to
netif_set_real_num_rx_queues() is not called with rtnl_lock held().

Fixes: 686cff3d7022 ("net: stmmac: Fix incorrect location to set real_num_rx|tx_queues")
Reported-by: Christophe ROULLIER <christophe.roullier@st.com>
Tested-by: Christophe ROULLIER <christophe.roullier@st.com>
Cc: Alexandre TORGUE <alexandre.torgue@st.com>
Reviewed-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: Wong Vee Khee <vee.khee.wong@intel.com>
---
v2 changelog:
- Move rtnl_lock() before priv->lock and release it after to avoid a
  possible ABBA deadlock scenario.
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ba855465a2db..c8770e9668a1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5272,6 +5272,7 @@ int stmmac_resume(struct device *dev)
 			return ret;
 	}
 
+	rtnl_lock();
 	mutex_lock(&priv->lock);
 
 	stmmac_reset_queues_param(priv);
@@ -5287,6 +5288,7 @@ int stmmac_resume(struct device *dev)
 	stmmac_enable_all_queues(priv);
 
 	mutex_unlock(&priv->lock);
+	rtnl_unlock();
 
 	if (!device_may_wakeup(priv->device) || !priv->plat->pmt) {
 		rtnl_lock();
-- 
2.17.0