From cef5ecf96b28dc91c4e9f398a336c578fb9e1a0c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 6 Jul 2015 05:18:05 -0700 Subject: [PATCH] net_sched: act_gact: make tcfg_pval non zero First step for gact RCU operation : Instead of testing if tcfg_pval is zero or not, just make it 1. No change in behavior, but slightly faster code. The smp_rmb()/smp_wmb() barriers, while not strictly needed at this stage are added for upcoming spinlock removal. Signed-off-by: Eric Dumazet Acked-by: Alexei Starovoitov Acked-by: Jamal Hadi Salim Acked-by: John Fastabend Signed-off-by: David S. Miller --- net/sched/act_gact.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/sched/act_gact.c b/net/sched/act_gact.c index a4f8af29ee30..22a3a61aa090 100644 --- a/net/sched/act_gact.c +++ b/net/sched/act_gact.c @@ -28,14 +28,16 @@ #ifdef CONFIG_GACT_PROB static int gact_net_rand(struct tcf_gact *gact) { - if (!gact->tcfg_pval || prandom_u32() % gact->tcfg_pval) + smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */ + if (prandom_u32() % gact->tcfg_pval) return gact->tcf_action; return gact->tcfg_paction; } static int gact_determ(struct tcf_gact *gact) { - if (!gact->tcfg_pval || gact->tcf_bstats.packets % gact->tcfg_pval) + smp_rmb(); /* coupled with smp_wmb() in tcf_gact_init() */ + if (gact->tcf_bstats.packets % gact->tcfg_pval) return gact->tcf_action; return gact->tcfg_paction; } @@ -105,7 +107,11 @@ static int tcf_gact_init(struct net *net, struct nlattr *nla, #ifdef CONFIG_GACT_PROB if (p_parm) { gact->tcfg_paction = p_parm->paction; - gact->tcfg_pval = p_parm->pval; + gact->tcfg_pval = max_t(u16, 1, p_parm->pval); + /* Make sure tcfg_pval is written before tcfg_ptype + * coupled with smp_rmb() in gact_net_rand() & gact_determ() + */ + smp_wmb(); gact->tcfg_ptype = p_parm->ptype; } #endif -- 2.30.2