netdev - [PATCH net 0/3] net_sched: sch_sfq: reject a derived limit of 1

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Message-ID: <20250328201634.3876474-1-tavip@google.com>
Date: Fri, 28 Mar 2025 13:16:31 -0700
From: Octavian Purdila <tavip@...gle.com>
To: jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, horms@...nel.org, shuah@...nel.org, netdev@...r.kernel.org, 
	Octavian Purdila <tavip@...gle.com>
Subject: [PATCH net 0/3] net_sched: sch_sfq: reject a derived limit of 1

Because sfq parameters can influence each other there can be
situations where although the user sets a limit of 2 it can be lowered
to 1:

$ tc qdisc add dev dummy0 handle 1: root sfq limit 2 flows 1 depth 1
$ tc qdisc show dev dummy0
qdisc sfq 1: dev dummy0 root refcnt 2 limit 1p quantum 1514b depth 1 divisor 1024

$ tc qdisc add dev dummy0 handle 1: root sfq limit 2 flows 10 depth 1 divisor 1
$ tc qdisc show dev dummy0
qdisc sfq 2: root refcnt 2 limit 1p quantum 1514b depth 1 divisor 1

As a limit of 1 is invalid, this patch series moves the limit
validation to after all configuration changes have been done. To do
so, the configuration is done in a temporary work area then applied to
the internal state.

The patch series also adds new test cases.

Octavian Purdila (3):
  net_sched: sch_sfq: use a temporary work area for validating
    configuration
  net_sched: sch_sfq: move the limit validation
  selftests/tc-testing: sfq: check that a derived limit of 1 is rejected

 net/sched/sch_sfq.c                           | 70 ++++++++++++++-----
 .../tc-testing/tc-tests/qdiscs/sfq.json       | 36 ++++++++++
 2 files changed, 90 insertions(+), 16 deletions(-)

-- 
2.49.0.472.ge94155a9ec-goog