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Date: Wed, 11 Dec 2013 19:51:14 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Terry Lam <vtlam@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
Nandita Dukkipati <nanditad@...gle.com>,
Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH v2] net-qdisc-hhf: Heavy-Hitter Filter (HHF) qdisc
On Wed, 2013-12-11 at 18:10 -0800, Terry Lam wrote:
> +static u32 hhf_time_stamp(void)
> +{
> + return jiffies;
> +}
This is a 32 bit value (For a good reason)
> +{
> + struct hh_flow_state *flow, *next;
> + unsigned long now = hhf_time_stamp();
stored in a 'unsigned long'
> +
> + if (list_empty(head))
> + return NULL;
> +
> + list_for_each_entry_safe(flow, next, head, flowchain) {
> + unsigned long prev = flow->hit_timestamp + q->hhf_evict_timeout;
32bit + ...
> +
> + if (time_before(prev, now)) {
This wont work on 64 bit arches : Wrapping wont be detected anymore.
We keep 32bit variables to lower memory usage,
this is why we have special macros in include/net/codel.h
Please make sure you test your v3 patch, there is no hurry ;)
Thanks !
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