Re: [PATCH net-next v2 2/2] net: migrate direct users to prandom_u32_max

[Daniel Borkmann]

On 09/04/2013 02:52 PM, Eric Dumazet wrote:
> On Wed, 2013-09-04 at 14:37 +0200, Daniel Borkmann wrote:
> > Users that directly use or reimplement what we have in prandom_u32_max()
> > can be migrated for now to use it directly, so that we can reduce code size
> > and avoid reimplementations. That's obvious, follow-up patches could inspect
> > modulo use cases for possible migration as well.
> >
> > Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
> > ---
> >   drivers/net/team/team_mode_random.c | 8 +-------
> >   include/net/red.h                   | 2 +-
> >   net/802/garp.c                      | 3 ++-
> >   net/802/mrp.c                       | 3 ++-
> >   net/packet/af_packet.c              | 2 +-
> >   net/sched/sch_choke.c               | 8 +-------
> >   6 files changed, 8 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/net/team/team_mode_random.c b/drivers/net/team/team_mode_random.c
> > index 7f032e2..0dbd1eb 100644
> > --- a/drivers/net/team/team_mode_random.c
> > +++ b/drivers/net/team/team_mode_random.c
> > @@ -13,20 +13,14 @@
> >   #include <linux/module.h>
> >   #include <linux/init.h>
> >   #include <linux/skbuff.h>
> > -#include <linux/reciprocal_div.h>
> >   #include <linux/if_team.h>
> >
> > -static u32 random_N(unsigned int N)
> > -{
> > -	return reciprocal_divide(prandom_u32(), N);
> > -}
> > -
> >   static bool rnd_transmit(struct team *team, struct sk_buff *skb)
> >   {
> >   	struct team_port *port;
> >   	int port_index;
> >
> > -	port_index = random_N(team->en_port_count);
> > +	port_index = prandom_u32_max(team->en_port_count - 1);
>
>
> Note the random_N(0) gave 0, while prandom_u32_max(0 - 1) can return any
> number in [0 ... ~0U]

Very true, that was stupid. Thanks for catching!
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