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Date: Mon, 11 Apr 2016 11:24:30 -0700
From: Stephen Hemminger <stephen@networkplumber.org>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Mirko Lindner <mlindner@marvell.com>
Subject: Re: Unhandled fault during system suspend in sky2_shutdown
Message-ID: <20160411112430.2a03e296@xeon-e3>
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On Mon, 11 Apr 2016 17:24:37 +0100
Sudeep Holla <sudeep.holla@arm.com> wrote:

> Hi,
> 
> I am seeing unhandled fault during system suspend in sky2_shutdown.
> I am not sure if it's something missing in the firmware, but just wanted
> to check. I see that networkmanager is invoking calling to 
> netlink_sendmsg which calls sky2_get_stats after the device is shutdown.
> 
> Unhandled fault: synchronous external abort (0x96000210) at 
> 0xffff0000091c2918
> Internal error: : 96000210 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 3 PID: 2029 Comm: NetworkManager Not tainted 4.6.0-rc3 #126
> Hardware name: ARM Juno development board (r2) (DT)
> task: ffff80007a673000 ti: ffff800940b5c000 task.ti: ffff800940b5c000
> PC is at sky2_get_stats+0x44/0x3b8
> LR is at dev_get_stats+0x58/0xc8
>   sky2_get_stats+0x44/0x3b8
>   rtnl_fill_stats+0x20/0x138
>   rtnl_fill_ifinfo+0x440/0xb38
>   rtnl_getlink+0xe8/0x198
>   rtnetlink_rcv_msg+0xe4/0x220
>   netlink_rcv_skb+0xc4/0xf8
>   rtnetlink_rcv+0x2c/0x40
>   netlink_unicast+0x160/0x238
>   netlink_sendmsg+0x2f0/0x358
>   sock_sendmsg+0x18/0x30
>   ___sys_sendmsg+0x204/0x218
>   __sys_sendmsg+0x44/0x88
>   SyS_sendmsg+0xc/0x18
>   el0_svc_naked+0x24/0x28
> 
> The below patch is the hack I came up to check if the netdev is detached 
> and unregistered, I no longer see the issue.
> 
> Regards,
> Sudeep
> 
> -->8  
> 
> diff --git i/drivers/net/ethernet/marvell/sky2.c 
> w/drivers/net/ethernet/marvell/sky2.c
> index ec0a22119e09..0ff0434e32fc 100644
> --- i/drivers/net/ethernet/marvell/sky2.c
> +++ w/drivers/net/ethernet/marvell/sky2.c
> @@ -5220,6 +5220,13 @@ static SIMPLE_DEV_PM_OPS(sky2_pm_ops, 
> sky2_suspend, sky2_resume);
> 
>   static void sky2_shutdown(struct pci_dev *pdev)
>   {
> +       struct sky2_hw *hw = pci_get_drvdata(pdev);
> +       int i;
> +
> +       for (i = hw->ports - 1; i >= 0; --i) {
> +               sky2_detach(hw->dev[i]);
> +               unregister_netdev(hw->dev[i]);
> +       }
>          sky2_suspend(&pdev->dev);
>          pci_wake_from_d3(pdev, device_may_wakeup(&pdev->dev));
>          pci_set_power_state(pdev, PCI_D3hot);

This is not the correct fix, the device is supposed to stay registered.
The correct way to fix this would be to make get_stats ignore requests for device
when suspended.