netdev - Re: [oss-drivers] [PATCH net-next 8/9] nfp: add a helper for wrapping descriptor index

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Date:   Tue, 16 May 2017 09:08:08 +0200
From:   Simon Horman <simon.horman@...ronome.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com
Subject: Re: [oss-drivers] [PATCH net-next 8/9] nfp: add a helper for
 wrapping descriptor index

On Mon, May 15, 2017 at 05:55:22PM -0700, Jakub Kicinski wrote:
> We have a number of places where we calculate the descriptor
> index based on a value which may have overflown.  Create a
> macro for masking with the ring size.
> 
> Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
> ---
>  drivers/net/ethernet/netronome/nfp/nfp_net.h        |  3 +++
>  drivers/net/ethernet/netronome/nfp/nfp_net_common.c | 21 ++++++++++-----------
>  2 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net.h b/drivers/net/ethernet/netronome/nfp/nfp_net.h
> index 66319a1026bb..7b9518cbe965 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfp_net.h
> +++ b/drivers/net/ethernet/netronome/nfp/nfp_net.h
> @@ -117,6 +117,9 @@ struct nfp_eth_table_port;
>  struct nfp_net;
>  struct nfp_net_r_vector;
>  
> +/* Convenience macro for wrapping descriptor index on ring size */
> +#define D_IDX(ring, idx)	((idx) & ((ring)->cnt - 1))

Any reason not to make this a function?

That notwithstanding:

Reviewed-by: Simon Horman <simon.horman@...ronome.com>