[Intel-wired-lan] [PATCH 02/10] igc: Refactor igc_xdp_run_prog()

[Maciej Fijalkowski]

On Thu, Dec 17, 2020 at 12:24:07PM -0800, Andre Guedes wrote:
> This patch refactors igc_xdp_run_prog() helper, preparing the code for

s/This patch refactors/Refactor

to follow the guideline of using the imperative mood in commit msgs.

> 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 the rx ring has zero-copy is enabled. To avoid code duplication as

The end of this sentence is a bit bogus.

What about:

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.

?

> much as possible, this patch encapsulates the code specific to handling

s/this patch encapsulates/encapsulate

git grep "This patch" Documentation/process/submitting-patches.rst

as a refresher :)

> XDP program actions into a local helper so it can be reused by the
> zero-copy path.
> 
> Signed-off-by: Andre Guedes <andre.guedes at 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 0e582a4ee986..56b791b356dc 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -2029,38 +2029,22 @@ 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,
> +			       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;
> @@ -2068,9 +2052,25 @@ 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();
> -- 
> 2.29.2
>