netdev - [PATCH net-next] net: sched: pie: change tc_pie

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Date:   Tue, 10 Mar 2020 00:40:33 +0530
From:   Leslie Monis <lesliemonis@...il.com>
To:     Linux NetDev <netdev@...r.kernel.org>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "Mohit P . Tahiliani" <tahiliani@...k.edu.in>,
        Gautam Ramakrishnan <gautamramk@...il.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] net: sched: pie: change tc_pie_xstats->prob

Commit 105e808c1da2 ("pie: remove pie_vars->accu_prob_overflows")
changes the scale of probability values in PIE from (2^64 - 1) to
(2^56 - 1). This affects the precision of tc_pie_xstats->prob in
user space.

This patch ensures user space is unaffected.

Suggested-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Leslie Monis <lesliemonis@...il.com>
---
 net/sched/sch_pie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c
index f52442d39bf5..c65077f0c0f3 100644
--- a/net/sched/sch_pie.c
+++ b/net/sched/sch_pie.c
@@ -493,7 +493,7 @@ static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 {
 	struct pie_sched_data *q = qdisc_priv(sch);
 	struct tc_pie_xstats st = {
-		.prob		= q->vars.prob,
+		.prob		= q->vars.prob << BITS_PER_BYTE,
 		.delay		= ((u32)PSCHED_TICKS2NS(q->vars.qdelay)) /
 				   NSEC_PER_USEC,
 		.packets_in	= q->stats.packets_in,
-- 
2.17.1