Re: [PATCH v2 net] net_sched: gen_estimator: fix broken estimators based on percpu stats

[David Miller]

From: Eric Dumazet 
Date: Thu, 22 Feb 2018 19:45:27 -0800

> From: Eric Dumazet 
> 
> 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 
> ---
> v2: Perform the zeroing in est_fetch_counters() instead of caller(s)

Applied and queued up for -stable.

[PATCH v2 net] net_sched: gen_estimator: fix broken estimators based on percpu stats

[Eric Dumazet]

From: Eric Dumazet 

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 
---
v2: Perform the zeroing in est_fetch_counters() instead of caller(s)

 net/core/gen_estimator.c |1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index 
0a3f88f08727f1f1217560407ff539c8a8c17496..98fd12721221e4aa26e4d11be9de6c0305fb6dd9
 100644
--- a/net/core/gen_estimator.c
+++ b/net/core/gen_estimator.c
@@ -66,6 +66,7 @@ struct net_rate_estimator {
 static void est_fetch_counters(struct net_rate_estimator *e,
   struct gnet_stats_basic_packed *b)
 {
+   memset(b, 0, sizeof(*b));
if (e->stats_lock)
spin_lock(e->stats_lock);