path: root/net/sched/sch_choke.c
diff options
authorDaniel Borkmann <dborkman@redhat.com>2014-01-22 02:29:39 +0100
committerDavid S. Miller <davem@davemloft.net>2014-01-21 23:17:20 -0800
commitf337db64af059c9a94278a8b0ab97d87259ff62f (patch)
treeef7db2258d5929760f2a22b74779d374916634bd /net/sched/sch_choke.c
parentnet/mlx4_core: Remove unnecessary validation for port number (diff)
random32: add prandom_u32_max and convert open coded users
Many functions have open coded a function that returns a random number in range [0,N-1]. Under the assumption that we have a PRNG such as taus113 with being well distributed in [0, ~0U] space, we can implement such a function as uword t = (n*m')>>32, where m' is a random number obtained from PRNG, n the right open interval border and t our resulting random number, with n,m',t in u32 universe. Lets go with Joe and simply call it prandom_u32_max(), although technically we have an right open interval endpoint, but that we have documented. Other users can further be migrated to the new prandom_u32_max() function later on; for now, we need to make sure to migrate reciprocal_divide() users for the reciprocal_divide() follow-up fixup since their function signatures are going to change. Joint work with Hannes Frederic Sowa. Cc: Jakub Zawadzki <darkjames-ws@darkjames.pl> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
1 files changed, 1 insertions, 8 deletions
diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index ddd73cb2d7ba..2aee02802c27 100644
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -14,7 +14,6 @@
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
-#include <linux/reciprocal_div.h>
#include <linux/vmalloc.h>
#include <net/pkt_sched.h>
#include <net/inet_ecn.h>
@@ -77,12 +76,6 @@ struct choke_sched_data {
struct sk_buff **tab;
-/* deliver a random number between 0 and N - 1 */
-static u32 random_N(unsigned int N)
- return reciprocal_divide(prandom_u32(), N);
/* number of elements in queue including holes */
static unsigned int choke_len(const struct choke_sched_data *q)
@@ -233,7 +226,7 @@ static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
int retrys = 3;
do {
- *pidx = (q->head + random_N(choke_len(q))) & q->tab_mask;
+ *pidx = (q->head + prandom_u32_max(choke_len(q))) & q->tab_mask;
skb = q->tab[*pidx];
if (skb)
return skb;