netdev - Re: [PATCH net] net_sched: gen_estimator: fix broken estimators based on percpu stats

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Message-ID: <1519357224.55655.64.camel@gmail.com>
Date:   Thu, 22 Feb 2018 19:40:24 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>
Subject: Re: [PATCH net] net_sched: gen_estimator: fix broken estimators
 based on percpu stats

On Thu, 2018-02-22 at 19:36 -0800, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> pfifo_fast got percpu stats lately, uncovering a bug I introduced last
> year in linux-4.10.
> 
> I missed the fact that we have to clear our temporary storage
> before calling __gnet_stats_copy_basic() in the case of percpu stats.
> 
> Without this fix, rate estimators (tc qd replace dev xxx root est 1sec
> 4sec pfifo_fast) are utterly broken.
> 
> Fixes: 1c0d32fde5bd ("net_sched: gen_estimator: complete rewrite of rate estimators")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
>  net/core/gen_estimator.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
> index 0a3f88f08727f1f1217560407ff539c8a8c17496..f13ea3c1fa3eddc6be172df9eda8828da76045e7 100644
> --- a/net/core/gen_estimator.c
> +++ b/net/core/gen_estimator.c
> @@ -79,7 +79,7 @@ static void est_fetch_counters(struct net_rate_estimator *e,
>  static void est_timer(struct timer_list *t)
>  {
>  	struct net_rate_estimator *est = from_timer(est, t, timer);
> -	struct gnet_stats_basic_packed b;
> +	struct gnet_stats_basic_packed b = {0};
>  	u64 rate, brate;
>  
>  	est_fetch_counters(est, &b);

Oh I sent the wrong version of the patch, sorry.

Will send a V2.