[Intel-wired-lan] [RFC PATCH] e1000: Do not perform reset in reset_task if we are already down

[Maxim Zhukov <mussitantesmortem@gmail.com>]

I applied this patch and ran the test. The first boot was successful.
I will write again after 500 reboots with result.

Thanks!

On Thu, Apr 16, 2020 at 01:34:19PM -0700, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> 
> We are seeing a deadlock in e1000 down when NAPI is being disabled. Looking
> over the kernel function trace of the system it appears that the interface
> is being closed and then a reset is hitting which deadlocks the interface
> as the NAPI interface is already disabled.
> 
> To prevent this from happening I am disabling the reset task when
> __E1000_DOWN is already set. In addition code has been added so that we set
> the __E1000_DOWN while holding the __E1000_RESET flag in e1000_close in
> order to guarantee that the reset task will not run after we have started
> the close call.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
> 
> Maxim,
> 
> If possible I would appreciate it if you could try this patch and see if
> it addresses the issues you were seeing. From what I can tell this issue
> is due to the interface being closed around the same time a reset is
> scheduled so the two are racing and resulting in down being called after
> a down was already completed. Adding this test for the down flag should
> correct that.
> 
> If it does I will resubmit this patch as a non-RFC.
> 
> Thanks.
> 
> Alex
> 
>  drivers/net/ethernet/intel/e1000/e1000_main.c |   18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index f7103356ef56..566bbcb74056 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -542,8 +542,13 @@ void e1000_reinit_locked(struct e1000_adapter *adapter)
>  	WARN_ON(in_interrupt());
>  	while (test_and_set_bit(__E1000_RESETTING, &adapter->flags))
>  		msleep(1);
> -	e1000_down(adapter);
> -	e1000_up(adapter);
> +
> +	/* only run the task if not already down */
> +	if (!test_bit(__E1000_DOWN, &adapter->flags)) {
> +		e1000_down(adapter);
> +		e1000_up(adapter);
> +	}
> +
>  	clear_bit(__E1000_RESETTING, &adapter->flags);
>  }
>  
> @@ -1433,10 +1438,15 @@ int e1000_close(struct net_device *netdev)
>  	struct e1000_hw *hw = &adapter->hw;
>  	int count = E1000_CHECK_RESET_COUNT;
>  
> -	while (test_bit(__E1000_RESETTING, &adapter->flags) && count--)
> +	while (test_and_set_bit(__E1000_RESETTING, &adapter->flags) && count--)
>  		usleep_range(10000, 20000);
>  
> -	WARN_ON(test_bit(__E1000_RESETTING, &adapter->flags));
> +	WARN_ON(count < 0);
> +
> +	/* signal that we're down so that the reset task will no longer run */
> +	set_bit(__E1000_DOWN, &adapter->flags);
> +	clear_bit(__E1000_RESETTING, &adapter->flags);
> +
>  	e1000_down(adapter);
>  	e1000_power_down_phy(adapter);
>  	e1000_free_irq(adapter);
>