netdev - Re: [net-next 3/6] ixgbe: release lock for the duration of ixgbe_suspend

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Date:   Fri, 18 May 2018 11:59:16 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>, davem@...emloft.net
Cc:     Pavel Tatashin <pasha.tatashin@...cle.com>, netdev@...r.kernel.org,
        nhorman@...hat.com, sassmann@...hat.com, jogreene@...hat.com
Subject: Re: [net-next 3/6] ixgbe: release lock for the duration of
 ixgbe_suspend_close()

Hello!

On 5/17/2018 7:37 PM, Jeff Kirsher wrote:

> From: Pavel Tatashin <pasha.tatashin@...cle.com>
> 
> Currently, during device_shutdown() ixgbe holds rtnl_lock for the duration
> of lengthy ixgbe_close_suspend(). On machines with multiple ixgbe cards
> this lock prevents scaling if device_shutdown() function is multi-threaded.
> 
> It is not necessary to hold this lock during ixgbe_close_suspend()
> as it is not held when ixgbe_close() is called also during shutdown but for
> kexec case.
> 
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
> Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> ---
>   drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index a52d92e182ee..5ddfb93ed491 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -6698,8 +6698,15 @@ static int __ixgbe_shutdown(struct pci_dev *pdev, bool *enable_wake)
>   	rtnl_lock();
>   	netif_device_detach(netdev);
>   
> -	if (netif_running(netdev))
> +	if (netif_running(netdev)) {
> +		/* Suspend takes a long time, device_shutdown may be
> +		 * parallelized this function, so drop lock for the

     Parallelizing? Else the sentence doesn't parse for me. :-)

> +		 * duration of this call.
> +		 */
> +		rtnl_unlock();
>   		ixgbe_close_suspend(adapter);
> +		rtnl_lock();
> +	}
>   
>   	ixgbe_clear_interrupt_scheme(adapter);
>   	rtnl_unlock();

MBR, Sergei