netdev - [PATCH net-next] net_sched: gen_estimator: extend packet counter to 64bit

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Message-Id: <20191107045240.211090-1-edumazet@google.com>
Date:   Wed,  6 Nov 2019 20:52:40 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next] net_sched: gen_estimator: extend packet counter to 64bit

I forgot to change last_packets field in struct net_rate_estimator.

Without this fix, rate estimators would misbehave after more
than 2^32 packets have been sent.

Another solution would be to be careful and only use the
32 least significant bits of packets counters, but we have
a hole in net_rate_estimator structure and this looks
easier to read/maintain.

Fixes: d0083d98f685 ("net_sched: extend packet counter to 64bit")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/gen_estimator.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index bfe7bdd4c3406a40e3b53b0b6c8260112691582e..80dbf2f4016e26824bc968115503ca2072933f63 100644
--- a/net/core/gen_estimator.c
+++ b/net/core/gen_estimator.c
@@ -48,7 +48,7 @@ struct net_rate_estimator {
 	u8			intvl_log; /* period : (250ms << intvl_log) */
 
 	seqcount_t		seq;
-	u32			last_packets;
+	u64			last_packets;
 	u64			last_bytes;
 
 	u64			avpps;
@@ -83,7 +83,7 @@ static void est_timer(struct timer_list *t)
 	brate = (b.bytes - est->last_bytes) << (10 - est->ewma_log - est->intvl_log);
 	brate -= (est->avbps >> est->ewma_log);
 
-	rate = (u64)(b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_log);
+	rate = (b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_log);
 	rate -= (est->avpps >> est->ewma_log);
 
 	write_seqcount_begin(&est->seq);
-- 
2.24.0.432.g9d3f5f5b63-goog