* [PATCH net 1/1] net: stmmac: Use rtnl_lock/unlock on netif_set_real_num_rx_queues() call
@ 2020-11-12 14:49 Wong Vee Khee
2020-11-14 20:45 ` Jakub Kicinski
0 siblings, 1 reply; 2+ messages in thread
From: Wong Vee Khee @ 2020-11-12 14:49 UTC (permalink / raw)
To: Giuseppe Cavallaro, Alexandre Torgue, Jose Abreu,
David S . Miller, Jakub Kicinski, Maxime Coquelin
Cc: netdev, linux-stm32, linux-arm-kernel, linux-kernel,
Ong Boon Leong, Voon Wei Feng, Wong Vee Khee,
Christophe ROULLIER
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>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ba855465a2db..33e280040000 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5278,7 +5278,10 @@ int stmmac_resume(struct device *dev)
stmmac_clear_descriptors(priv);
+ rtnl_lock();
stmmac_hw_setup(ndev, false);
+ rtnl_unlock();
+
stmmac_init_coalesce(priv);
stmmac_set_rx_mode(ndev);
--
2.17.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net 1/1] net: stmmac: Use rtnl_lock/unlock on netif_set_real_num_rx_queues() call
2020-11-12 14:49 [PATCH net 1/1] net: stmmac: Use rtnl_lock/unlock on netif_set_real_num_rx_queues() call Wong Vee Khee
@ 2020-11-14 20:45 ` Jakub Kicinski
0 siblings, 0 replies; 2+ messages in thread
From: Jakub Kicinski @ 2020-11-14 20:45 UTC (permalink / raw)
To: Wong Vee Khee
Cc: Giuseppe Cavallaro, Alexandre Torgue, Jose Abreu,
David S . Miller, Maxime Coquelin, netdev, linux-stm32,
linux-arm-kernel, linux-kernel, Ong Boon Leong, Voon Wei Feng,
Christophe ROULLIER
On Thu, 12 Nov 2020 22:49:48 +0800 Wong Vee Khee wrote:
> 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>
> ---
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index ba855465a2db..33e280040000 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -5278,7 +5278,10 @@ int stmmac_resume(struct device *dev)
>
> stmmac_clear_descriptors(priv);
>
> + rtnl_lock();
> stmmac_hw_setup(ndev, false);
> + rtnl_unlock();
> +
> stmmac_init_coalesce(priv);
> stmmac_set_rx_mode(ndev);
>
Doesn't look quite right. This is under the priv->lock which is
sometimes taken under rtnl_lock. So theoretically there could be
a deadlock.
You should probably take rtnl_lock() before priv->lock and release
it after. It's pretty common for drivers to hold rtnl_lock around
most of the resume method.
With larger context:
mutex_lock(&priv->lock);
stmmac_reset_queues_param(priv);
stmmac_clear_descriptors(priv);
+ rtnl_lock();
stmmac_hw_setup(ndev, false);
+ rtnl_unlock();
+
stmmac_init_coalesce(priv);
stmmac_set_rx_mode(ndev);
stmmac_restore_hw_vlan_rx_fltr(priv, ndev, priv->hw);
stmmac_enable_all_queues(priv);
mutex_unlock(&priv->lock);
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