From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: David Miller <davem@davemloft.net>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
oss-drivers@netronome.com,
Stephen Hemminger <stephen@networkplumber.org>,
kbuild test robot <lkp@intel.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
Ben Hutchings <ben@decadent.org.uk>,
Simon Horman <simon.horman@netronome.com>
Subject: Re: [PATCH net] net: netem: fix error path for corrupted GSO frames
Date: Thu, 17 Oct 2019 11:44:04 -0700 [thread overview]
Message-ID: <20191017114404.4fb502c6@cakuba.netronome.com> (raw)
In-Reply-To: <CAM_iQpW=S+UarEKCtL6q_ZyxVn0chVLgXQyfRNP_Kw-P8_Qt+Q@mail.gmail.com>
On Thu, 17 Oct 2019 11:10:06 -0700, Cong Wang wrote:
> On Wed, Oct 16, 2019 at 4:22 PM Jakub Kicinski wrote:
> > On Wed, 16 Oct 2019 15:42:28 -0700, Cong Wang wrote:
> > > > @@ -612,7 +613,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
> > > > }
> > > > segs = skb2;
> > > > }
> > > > - qdisc_tree_reduce_backlog(sch, -nb, prev_len - len);
> > > > + qdisc_tree_reduce_backlog(sch, !skb - nb, prev_len - len);
> > >
> > > Am I the only one has trouble to understand the expression
> > > "!skb - nb"?
> >
> > The backward logic of qdisc_tree_reduce_backlog() always gives me a
> > pause :S
>
> Yeah, reducing with a negative value is actually an add. Feel free
> to add a wrapper for this if you think it is better.
I was avoiding adding the wrapper due to stable, but perhaps it should
be okay.
How does this look?
--->8--------------
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 637548d54b3e..66c2dc6a4742 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -630,6 +630,13 @@ void qdisc_reset(struct Qdisc *qdisc);
void qdisc_put(struct Qdisc *qdisc);
void qdisc_put_unlocked(struct Qdisc *qdisc);
void qdisc_tree_reduce_backlog(struct Qdisc *qdisc, int n, int len);
+
+static inline void
+qdisc_tree_increase_backlog(struct Qdisc *qdisc, int n, int len)
+{
+ qdisc_tree_reduce_backlog(qdisc, -n, -len);
+}
+
#ifdef CONFIG_NET_SCHED
int qdisc_offload_dump_helper(struct Qdisc *q, enum tc_setup_type type,
void *type_data);
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0e44039e729c..e22c13b56bfc 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -509,6 +509,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
if (skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_help(skb)) {
qdisc_drop(skb, sch, to_free);
+ skb = NULL;
goto finish_segs;
}
@@ -592,10 +593,13 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
finish_segs:
if (segs) {
- unsigned int len, last_len;
+ unsigned int last_len, len = 0;
int nb = 0;
- len = skb->len;
+ if (skb) {
+ len += skb->len;
+ nb++;
+ }
while (segs) {
skb2 = segs->next;
@@ -612,7 +616,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
}
segs = skb2;
}
- qdisc_tree_reduce_backlog(sch, -nb, prev_len - len);
+ /* Parent qdiscs accounted for 1 skb of size @prev_len */
+ qdisc_tree_increase_backlog(sch, nb - 1, len - prev_len);
}
return NET_XMIT_SUCCESS;
}
next prev parent reply other threads:[~2019-10-17 18:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 16:00 [PATCH net] net: netem: fix error path for corrupted GSO frames Jakub Kicinski
2019-10-16 22:42 ` Cong Wang
2019-10-16 23:22 ` Jakub Kicinski
2019-10-17 18:10 ` Cong Wang
2019-10-17 18:44 ` Jakub Kicinski [this message]
2019-10-17 19:28 ` Cong Wang
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