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Subject[PATCH 4.4 077/135] net: Revert "pkt_sched: fq: use proper locking in fq_dump_stats()"
Date
From: Toke Høiland-Jørgensen <toke@redhat.com>

This reverts commit 191cf872190de28a92e1bd2b56d8860e37e07443 which is
commit 695b4ec0f0a9cf29deabd3ac075911d58b31f42b upstream.

That commit should never have been backported since it relies on a change in
locking semantics that was introduced in v4.8 and not backported. Because of
this, the backported commit to sch_fq leads to lockups because of the double
locking.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/sch_fq.c | 32 ++++++++++++++------------------
1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index f4aa2ab4713a2..eb814ffc09023 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -830,24 +830,20 @@ static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
static int fq_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
struct fq_sched_data *q = qdisc_priv(sch);
- struct tc_fq_qd_stats st;
-
- sch_tree_lock(sch);
-
- st.gc_flows = q->stat_gc_flows;
- st.highprio_packets = q->stat_internal_packets;
- st.tcp_retrans = q->stat_tcp_retrans;
- st.throttled = q->stat_throttled;
- st.flows_plimit = q->stat_flows_plimit;
- st.pkts_too_long = q->stat_pkts_too_long;
- st.allocation_errors = q->stat_allocation_errors;
- st.time_next_delayed_flow = q->time_next_delayed_flow - ktime_get_ns();
- st.flows = q->flows;
- st.inactive_flows = q->inactive_flows;
- st.throttled_flows = q->throttled_flows;
- st.pad = 0;
-
- sch_tree_unlock(sch);
+ u64 now = ktime_get_ns();
+ struct tc_fq_qd_stats st = {
+ .gc_flows = q->stat_gc_flows,
+ .highprio_packets = q->stat_internal_packets,
+ .tcp_retrans = q->stat_tcp_retrans,
+ .throttled = q->stat_throttled,
+ .flows_plimit = q->stat_flows_plimit,
+ .pkts_too_long = q->stat_pkts_too_long,
+ .allocation_errors = q->stat_allocation_errors,
+ .flows = q->flows,
+ .inactive_flows = q->inactive_flows,
+ .throttled_flows = q->throttled_flows,
+ .time_next_delayed_flow = q->time_next_delayed_flow - now,
+ };

return gnet_stats_copy_app(d, &st, sizeof(st));
}
--
2.25.1
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