[PATCH 5.12 032/296] net/sched: fq_pie: re-factor fix for fq_pie endless loop

Greg Kroah-Hartman
2021-05-31T16:03:12Z

From: Davide Caratti <dcaratti@redhat.com>

commit 3a62fed2fd7b6fea96d720e779cafc30dfb3a22e upstream.

the patch that fixed an endless loop in_fq_pie_init() was not considering
that 65535 is a valid class id. The correct bugfix for this infinite loop
is to change 'idx' to become an u32, like Colin proposed in the past [1].

Fix this as follows:
- restore 65536 as maximum possible values of 'flows_cnt'
- use u32 'idx' when iterating on 'q->flows'
- fix the TDC selftest

This reverts commit bb2f930d6dd708469a587dc9ed1efe1ef969c0bf.

[1] https://lore.kernel.org/netdev/20210407163808.499027-1-colin.king@canonical.com/

CC: Colin Ian King <colin.king@canonical.com>
CC: stable@vger.kernel.org
Fixes: bb2f930d6dd7 ("net/sched: fix infinite loop in sch_fq_pie")
Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/sch_fq_pie.c | 10 +++++-----
tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json | 8 ++++----
2 files changed, 9 insertions(+), 9 deletions(-)

--- a/net/sched/sch_fq_pie.c
+++ b/net/sched/sch_fq_pie.c
@@ -297,9 +297,9 @@ static int fq_pie_change(struct Qdisc *s
goto flow_error;
}
q->flows_cnt = nla_get_u32(tb[TCA_FQ_PIE_FLOWS]);
- if (!q->flows_cnt || q->flows_cnt >= 65536) {
+ if (!q->flows_cnt || q->flows_cnt > 65536) {
NL_SET_ERR_MSG_MOD(extack,
- "Number of flows must range in [1..65535]");
+ "Number of flows must range in [1..65536]");
goto flow_error;
}
}
@@ -367,7 +367,7 @@ static void fq_pie_timer(struct timer_li
struct fq_pie_sched_data *q = from_timer(q, t, adapt_timer);
struct Qdisc *sch = q->sch;
spinlock_t *root_lock; /* to lock qdisc for probability calculations */
- u16 idx;
+ u32 idx;

root_lock = qdisc_lock(qdisc_root_sleeping(sch));
spin_lock(root_lock);
@@ -388,7 +388,7 @@ static int fq_pie_init(struct Qdisc *sch
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
int err;
- u16 idx;
+ u32 idx;

pie_params_init(&q->p_params);
sch->limit = 10 * 1024;
@@ -500,7 +500,7 @@ static int fq_pie_dump_stats(struct Qdis
static void fq_pie_reset(struct Qdisc *sch)
{
struct fq_pie_sched_data *q = qdisc_priv(sch);
- u16 idx;
+ u32 idx;

INIT_LIST_HEAD(&q->new_flows);
INIT_LIST_HEAD(&q->old_flows);
--- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
@@ -9,11 +9,11 @@
"setup": [
"$IP link add dev $DUMMY type dummy || /bin/true"
],
- "cmdUnderTest": "$TC qdisc add dev $DUMMY root fq_pie flows 65536",
- "expExitCode": "2",
+ "cmdUnderTest": "$TC qdisc add dev $DUMMY handle 1: root fq_pie flows 65536",
+ "expExitCode": "0",
"verifyCmd": "$TC qdisc show dev $DUMMY",
- "matchPattern": "qdisc",
- "matchCount": "0",
+ "matchPattern": "qdisc fq_pie 1: root refcnt 2 limit 10240p flows 65536",
+ "matchCount": "1",
"teardown": [
"$IP link del dev $DUMMY"
]