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| author | Martin Ottens <martin.ottens@fau.de> | 2024-11-25 18:46:07 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-12-14 19:44:45 +0100 |
| commit | dfc2e5802842dc2c0e31f7bb92c0e7e57eabfabb (patch) | |
| tree | 508568f684dc5237d00457d4d4c351843941e841 /net | |
| parent | 147a42bb02de8735cb08476be6d0917987d022c2 (diff) | |
| download | linux-dfc2e5802842dc2c0e31f7bb92c0e7e57eabfabb.tar.gz linux-dfc2e5802842dc2c0e31f7bb92c0e7e57eabfabb.tar.bz2 linux-dfc2e5802842dc2c0e31f7bb92c0e7e57eabfabb.zip | |
net/sched: tbf: correct backlog statistic for GSO packets
[ Upstream commit 1596a135e3180c92e42dd1fbcad321f4fb3e3b17 ]
When the length of a GSO packet in the tbf qdisc is larger than the burst
size configured the packet will be segmented by the tbf_segment function.
Whenever this function is used to enqueue SKBs, the backlog statistic of
the tbf is not increased correctly. This can lead to underflows of the
'backlog' byte-statistic value when these packets are dequeued from tbf.
Reproduce the bug:
Ensure that the sender machine has GSO enabled. Configured the tbf on
the outgoing interface of the machine as follows (burstsize = 1 MTU):
$ tc qdisc add dev <oif> root handle 1: tbf rate 50Mbit burst 1514 latency 50ms
Send bulk TCP traffic out via this interface, e.g., by running an iPerf3
client on this machine. Check the qdisc statistics:
$ tc -s qdisc show dev <oif>
The 'backlog' byte-statistic has incorrect values while traffic is
transferred, e.g., high values due to u32 underflows. When the transfer
is stopped, the value is != 0, which should never happen.
This patch fixes this bug by updating the statistics correctly, even if
single SKBs of a GSO SKB cannot be enqueued.
Fixes: e43ac79a4bc6 ("sch_tbf: segment too big GSO packets")
Signed-off-by: Martin Ottens <martin.ottens@fau.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241125174608.1484356-1-martin.ottens@fau.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/sch_tbf.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c index a7f60bb2dd51..259a39ca99bf 100644 --- a/net/sched/sch_tbf.c +++ b/net/sched/sch_tbf.c @@ -146,7 +146,7 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, struct tbf_sched_data *q = qdisc_priv(sch); struct sk_buff *segs, *nskb; netdev_features_t features = netif_skb_features(skb); - unsigned int len = 0, prev_len = qdisc_pkt_len(skb); + unsigned int len = 0, prev_len = qdisc_pkt_len(skb), seg_len; int ret, nb; segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); @@ -158,22 +158,28 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, while (segs) { nskb = segs->next; skb_mark_not_on_list(segs); - qdisc_skb_cb(segs)->pkt_len = segs->len; - len += segs->len; + seg_len = segs->len; + qdisc_skb_cb(segs)->pkt_len = seg_len; ret = qdisc_enqueue(segs, q->qdisc, to_free); if (ret != NET_XMIT_SUCCESS) { if (net_xmit_drop_count(ret)) qdisc_qstats_drop(sch); } else { nb++; + len += seg_len; } segs = nskb; } sch->q.qlen += nb; - if (nb > 1) + sch->qstats.backlog += len; + if (nb > 0) { qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); - consume_skb(skb); - return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; + consume_skb(skb); + return NET_XMIT_SUCCESS; + } + + kfree_skb(skb); + return NET_XMIT_DROP; } static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch, |