netdev - Re: [net-next 16/20] fm10k: check if PCIe link is restored

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Message-ID: <63e931a3-e447-5a1f-f998-578e1cb2eb8e@cogentembedded.com>
Date:	Thu, 21 Jul 2016 13:51:54 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>, davem@...emloft.net
Cc:	Jacob Keller <jacob.e.keller@...el.com>, netdev@...r.kernel.org,
	nhorman@...hat.com, sassmann@...hat.com, jogreene@...hat.com,
	guru.anbalagane@...cle.com
Subject: Re: [net-next 16/20] fm10k: check if PCIe link is restored

Hello.

On 7/21/2016 1:23 AM, Jeff Kirsher wrote:

> From: Jacob Keller <jacob.e.keller@...el.com>
>
> Sometimes, a VF driver will lose PCIe address access, such as due to
> a PF FLR event. In fm10k_detach_subtask, poll and check whether the
> PCIe register space is active again and restore the device when it has.
>
> Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
> Tested-by: Krishneil Singh <Krishneil.k.singh@...el.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> ---
>  drivers/net/ethernet/intel/fm10k/fm10k_pci.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
> index 5e40460..d4ccb2a 100644
> --- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
> +++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
> @@ -123,11 +123,24 @@ static void fm10k_service_timer(unsigned long data)
>  static void fm10k_detach_subtask(struct fm10k_intfc *interface)
>  {
>  	struct net_device *netdev = interface->netdev;
> +	u32 __iomem *hw_addr;
> +	u32 value;
>
>  	/* do nothing if device is still present or hw_addr is set */
>  	if (netif_device_present(netdev) || interface->hw.hw_addr)
>  		return;
>
> +	/* check the real address space to see if we've recovered */
> +	hw_addr = READ_ONCE(interface->uc_addr);
> +	value = readl(hw_addr);
> +	if ((~value)) {

    Why these double parens?

[...]

MBR, Sergei