Commit 1daa6591 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'net_sched-sch_sfq-reject-limit-of-1' 

Octavian Purdila says:

====================
net_sched: sch_sfq: reject limit of 1

The implementation does not properly support limits of 1. Add an
in-kernel check, in addition to existing iproute2 check, since other
tools may be used for configuration.

This patch set also adds a selfcheck to test that a limit of 1 is
rejected.

An alternative (or in addition) we could fix the implementation by
setting q->tail to NULL in sfq_drop if this is the last slot we marked
empty, e.g.:

  --- a/net/sched/sch_sfq.c
  +++ b/net/sched/sch_sfq.c
  @@ -317,8 +317,11 @@ static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free)
                  /* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
                  x = q->tail->next;
                  slot = &q->slots[x];
  -               q->tail->next = slot->next;
                  q->ht[slot->hash] = SFQ_EMPTY_SLOT;
  +               if (x == slot->next)
  +                       q->tail = NULL; /* no more active slots */
  +               else
  +                       q->tail->next = slot->next;
                  goto drop;
          }
====================

Link: https://patch.msgid.link/20241204030520.2084663-1-tavip@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 5765c7f6 1e7e1f0e

net/sched/sch_sfq.c

+4 −0
Original line number Diff line number Diff line
@@ -652,6 +652,10 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt, 
		if (!p)

			return -ENOMEM;

	}

	if (ctl->limit == 1) {

		NL_SET_ERR_MSG_MOD(extack, "invalid limit");

		return -EINVAL;

	}

	sch_tree_lock(sch);

	if (ctl->quantum)

		q->quantum = ctl->quantum;

tools/testing/selftests/tc-testing/scripts/sfq_rejects_limit_1.py

0 → 100755
+21 −0
Original line number Diff line number Diff line 
#!/usr/bin/env python3

# SPDX-License-Identifier: GPL-2.0

#

# Script that checks that SFQ rejects a limit of 1 at the kernel

# level. We can't use iproute2's tc because it does not accept a limit

# of 1.



import sys

import os



from pyroute2 import IPRoute

from pyroute2.netlink.exceptions import NetlinkError



ip = IPRoute()

ifidx = ip.link_lookup(ifname=sys.argv[1])



try:

    ip.tc('add', 'sfq', ifidx, limit=1)

    sys.exit(1)

except NetlinkError:

    sys.exit(0)

tools/testing/selftests/tc-testing/tc-tests/qdiscs/sfq.json

+20 −0
Original line number Diff line number Diff line
@@ -208,5 +208,25 @@ 
        "teardown": [

            "$TC qdisc del dev $DUMMY handle 1: root"

        ]

    },

    {

        "id": "4d6f",

        "name": "Check that limit of 1 is rejected",

        "category": [

            "qdisc",

            "sfq"

        ],

        "plugins": {

            "requires": "nsPlugin"

        },

        "setup": [

        ],

        "cmdUnderTest": "./scripts/sfq_rejects_limit_1.py $DUMMY",

        "expExitCode": "0",

        "verifyCmd": "$TC qdisc show dev $DUMMY",

        "matchPattern": "sfq",

        "matchCount": "0",

        "teardown": [

        ]

    }

]