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

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Message-ID: <20170516082225.GA15081@vergenet.net>
Date:   Tue, 16 May 2017 10:22:28 +0200
From:   Simon Horman <simon.horman@...ronome.com>
To:     Jakub Kicinski <kubakici@...pl>
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 Tue, May 16, 2017 at 12:38:57AM -0700, Jakub Kicinski wrote:
> On Tue, 16 May 2017 09:08:08 +0200, Simon Horman wrote:
> > 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?
> 
> This is to be able to use the same macro for both RX and TX rings.  If
> you look below in the code I have a macro for setting dma addresses on
> descriptors also regardless of the type.
> 
> It makes the code a tiny bit cleaner IMHO and should be acceptable for
> trivial macros.

Thanks for the clarification, that sounds reasonable to me.

> > That notwithstanding:
> > 
> > Reviewed-by: Simon Horman <simon.horman@...ronome.com>
> 
> Thanks for the reviews!