[Intel-wired-lan] [PATCH 1/2] fm10k: napi polling routine must return actual work done

[Keller, Jacob E]

> -----Original Message-----
> From: Keller, Jacob E
> Sent: Monday, June 20, 2016 10:40 AM
> To: Intel Wired LAN <intel-wired-lan at lists.osuosl.org>
> Cc: Keller, Jacob E <jacob.e.keller at intel.com>; Paolo Abeni
> <pabeni at redhat.com>; Venkatesh Srinivas <venkateshs at google.com>;
> Alexander Duyck <aduyck at mirantis.com>
> Subject: [PATCH 1/2] fm10k: napi polling routine must return actual work
> done
> 
> When fm10k_poll fully cleans rings it returns 0. This is incorrect as it
> messes up the budget accounting in the core napi code. Fix this by
> returning actual work done, capped at budget - 1 since the core doesn't
> expect a return of the full budget when the driver modifies the napi
> status.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>
> Cc: Paolo Abeni <pabeni at redhat.com>
> Cc: Venkatesh Srinivas <venkateshs at google.com>
> Cc: Alexander Duyck <aduyck at mirantis.com>
> ---
>  drivers/net/ethernet/intel/fm10k/fm10k_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_main.c
> b/drivers/net/ethernet/intel/fm10k/fm10k_main.c
> index 682a372bdb20..79d5093d83d1 100644
> --- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c
> +++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c
> @@ -1484,7 +1484,7 @@ static int fm10k_poll(struct napi_struct *napi, int
> budget)
>  	/* re-enable the q_vector */
>  	fm10k_qv_enable(q_vector);
> 
> -	return 0;
> +	return min(work_done, budget - 1);


This patch potentially appears to be caused Tx hangs in the napi routines in the stack, when under heavy traffic pressure. It appears that other drivers (i40e, and ixgbe) don't do this either, so I am not sure which is correct...

>  }
> 
>  /**
> --
> 2.9.0.rc1.405.g81f467e