[PATCH 4.15 062/122] net_sched: gen_estimator: fix broken estimators based on percpu stats

From: Greg Kroah-Hartman
Date: Wed Mar 07 2018 - 15:39:03 EST


4.15-stable review patch. If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>


[ Upstream commit a5f7add332b4ea6d4b9480971b3b0f5e66466ae9 ]

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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/gen_estimator.c | 1 +
1 file changed, 1 insertion(+)

--- 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);