[PATCH 3.16 051/306] pkt_sched: fq: use proper locking in fq_dump_stats()

Ben Hutchings
2017-02-15T23:32:27Z

From: Eric Dumazet <edumazet@google.com>

commit 695b4ec0f0a9cf29deabd3ac075911d58b31f42b upstream.

When fq is used on 32bit kernels, we need to lock the qdisc before
copying 64bit fields.

Otherwise "tc -s qdisc ..." might report bogus values.

Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: keep using ktime_to_ns(ktime_get())]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/sched/sch_fq.c | 32 ++++++++++++++++++--------------
1 file changed, 18 insertions(+), 14 deletions(-)

--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -789,20 +789,24 @@ nla_put_failure:
static int fq_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
struct fq_sched_data *q = qdisc_priv(sch);
- u64 now = ktime_to_ns(ktime_get());
- 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,
- };
+ 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_to_ns(ktime_get());
+ st.flows = q->flows;
+ st.inactive_flows = q->inactive_flows;
+ st.throttled_flows = q->throttled_flows;
+ st.pad = 0;
+
+ sch_tree_unlock(sch);

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