[Intel-wired-lan] [PATCH net-next v3 2/9] igc: Refactor igc_xdp_run_prog()

[Maciej Fijalkowski <maciej.fijalkowski@intel.com>]

On Mon, Feb 08, 2021 at 06:42:36PM -0800, Vedang Patel wrote:
> From: Andre Guedes <andre.guedes@intel.com>
> 
> Refactor igc_xdp_run_prog() helper, preparing the code for AF_XDP
> zero-copy support which is added by upcoming patches.
> 
> With AF_XDP zero-copy support, igc_poll() will have a dedicated path
> when rx ring's memory model is MEM_TYPE_XSK_BUFF_POOL. To avoid code
> duplication as much as possible, encapsulate the code specific to
> handling XDP program actions into a local helper so it can be reused by
> the zero-copy path.

Hey Vedang, I'm not sure why you didn't include my reviewed-by tag for the
series from v2, so I'm looking at that again.

Please mention that the ZC path can assume that bpf_prog will always be
!NULL and we don't have to check that explicitly, therefore it makes sense
to pull out the common logic.

> 
> Signed-off-by: Andre Guedes <andre.guedes@intel.com>
> Signed-off-by: Vedang Patel <vedang.patel@intel.com>
> ---
>  drivers/net/ethernet/intel/igc/igc_main.c | 56 +++++++++++------------
>  1 file changed, 28 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index 59a341566bc6..151ac078df48 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -2012,38 +2012,22 @@ static int igc_xdp_xmit_back(struct igc_adapter *adapter, struct xdp_buff *xdp)
>  	return res;
>  }
>  
> -static struct sk_buff *igc_xdp_run_prog(struct igc_adapter *adapter,
> -					struct xdp_buff *xdp)
> +/* This function assumes rcu_read_lock() is held by the caller. */
> +static int igc_xdp_do_run_prog(struct igc_adapter *adapter,

nit: I feel like __igc_xdp_run_prog would be a better fit

> +			       struct bpf_prog *prog,
> +			       struct xdp_buff *xdp)
>  {
> -	struct bpf_prog *prog;
> -	int res;
> -	u32 act;
> -
> -	rcu_read_lock();
> -
> -	prog = READ_ONCE(adapter->xdp_prog);
> -	if (!prog) {
> -		res = IGC_XDP_PASS;
> -		goto unlock;
> -	}
> +	u32 act = bpf_prog_run_xdp(prog, xdp);
>  
> -	act = bpf_prog_run_xdp(prog, xdp);
>  	switch (act) {
>  	case XDP_PASS:
> -		res = IGC_XDP_PASS;
> -		break;
> +		return IGC_XDP_PASS;
>  	case XDP_TX:
> -		if (igc_xdp_xmit_back(adapter, xdp) < 0)
> -			res = IGC_XDP_CONSUMED;
> -		else
> -			res = IGC_XDP_TX;
> -		break;
> +		return igc_xdp_xmit_back(adapter, xdp) < 0 ?
> +			IGC_XDP_CONSUMED : IGC_XDP_TX;
>  	case XDP_REDIRECT:
> -		if (xdp_do_redirect(adapter->netdev, xdp, prog) < 0)
> -			res = IGC_XDP_CONSUMED;
> -		else
> -			res = IGC_XDP_REDIRECT;
> -		break;
> +		return xdp_do_redirect(adapter->netdev, xdp, prog) < 0 ?
> +			IGC_XDP_CONSUMED : IGC_XDP_REDIRECT;
>  	default:
>  		bpf_warn_invalid_xdp_action(act);
>  		fallthrough;
> @@ -2051,9 +2035,25 @@ static struct sk_buff *igc_xdp_run_prog(struct igc_adapter *adapter,
>  		trace_xdp_exception(adapter->netdev, prog, act);
>  		fallthrough;
>  	case XDP_DROP:
> -		res = IGC_XDP_CONSUMED;
> -		break;
> +		return IGC_XDP_CONSUMED;
>  	}
> +}
> +
> +static struct sk_buff *igc_xdp_run_prog(struct igc_adapter *adapter,
> +					struct xdp_buff *xdp)
> +{
> +	struct bpf_prog *prog;
> +	int res;
> +
> +	rcu_read_lock();
> +
> +	prog = READ_ONCE(adapter->xdp_prog);
> +	if (!prog) {
> +		res = IGC_XDP_PASS;
> +		goto unlock;
> +	}
> +
> +	res = igc_xdp_do_run_prog(adapter, prog, xdp);
>  
>  unlock:
>  	rcu_read_unlock();
> -- 
> 2.17.1
> 
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