linux-toradex.git/net/sched/sch_fq_codel.c, branch v6.11

net_sched: sch_fq_codel: implement lockless fq_codel_dump()

2024-04-19T10:34:07+00:00

Instead of relying on RTNL, fq_codel_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in fq_codel_change().

Signed-off-by: Eric Dumazet 
Reviewed-by: Simon Horman 
Signed-off-by: David S. Miller

net/sched: Add module aliases for cls_,sch_,act_ modules

2024-02-02T18:57:55+00:00

No functional change intended, aliases will be used in followup commits.
Note for backporters: you may need to add aliases also for modules that
are already removed in mainline kernel but still in your version.

Patches were generated with the help of Coccinelle scripts like:

cat >scripts/coccinelle/misc/tcf_alias.cocci </dev/null | \
        sed 's/char module_alias = "\([^"]*\)";/MODULE_ALIAS_NET_CLS("\1");/'

And analogously for:

  static struct tc_action_ops ops = {
    .kind = K,

  static struct Qdisc_ops ops = {
    .id = K,

(Someone familiar would be able to fit those into one .cocci file
without sed post processing.)

Signed-off-by: Michal Koutný 
Acked-by: Jamal Hadi Salim 
Reviewed-by: Jiri Pirko 
Link: https://lore.kernel.org/r/20240201130943.19536-3-mkoutny@suse.com
Signed-off-by: Jakub Kicinski

Revert "net: sched: fq_codel: remove redundant resource cleanup in fq_codel_init()"

2022-10-19T12:47:09+00:00

This reverts commit 494f5063b86cd6e972cb41a27e083c9a3664319d.

When the default qdisc is fq_codel, if the qdisc of dev_queue fails to be
inited during mqprio_init(), fq_codel_reset() is invoked to clear
resources. In this case, the flow is NULL, and it will cause gpf issue.

The process is as follows:
qdisc_create_dflt()
	fq_codel_init()
		...
		q->flows_cnt = 1024;
		...
		q->flows = kvcalloc(...)      --->failed, q->flows is NULL
	...
	qdisc_put()
		...
		fq_codel_reset()
			...
			flow = q->flows + i   --->q->flows is NULL

The following is the Call Trace information:
general protection fault, probably for non-canonical address
0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
RIP: 0010:fq_codel_reset+0x14d/0x350
Call Trace:

qdisc_reset+0xed/0x6f0
qdisc_destroy+0x82/0x4c0
qdisc_put+0x9e/0xb0
qdisc_create_dflt+0x2c3/0x4a0
mqprio_init+0xa71/0x1760
qdisc_create+0x3eb/0x1000
tc_modify_qdisc+0x408/0x1720
rtnetlink_rcv_msg+0x38e/0xac0
netlink_rcv_skb+0x12d/0x3a0
netlink_unicast+0x4a2/0x740
netlink_sendmsg+0x826/0xcc0
sock_sendmsg+0xc5/0x100
____sys_sendmsg+0x583/0x690
___sys_sendmsg+0xe8/0x160
__sys_sendmsg+0xbf/0x160
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7fd272b22d04


Signed-off-by: Zhengchao Shao 
Signed-off-by: David S. Miller

net/sched: use tc_qdisc_stats_dump() in qdisc

2022-09-23T00:34:10+00:00

use tc_qdisc_stats_dump() in qdisc.

Signed-off-by: Zhengchao Shao 
Reviewed-by: Victor Nogueira 
Tested-by: Victor Nogueira 
Acked-by: Toke Høiland-Jørgensen 
Signed-off-by: Jakub Kicinski

net: sched: fq_codel: remove redundant resource cleanup in fq_codel_init()

2022-09-03T09:40:40+00:00

If fq_codel_init() fails, qdisc_create() invokes fq_codel_destroy() to
clear resources. Therefore, remove redundant resource cleanup in
fq_codel_init().

Signed-off-by: Zhengchao Shao 
Signed-off-by: David S. Miller

net: sched: remove redundant NULL check in change hook function

2022-09-01T06:06:45+00:00

Currently, the change function can be called by two ways. The one way is
that qdisc_change() will call it. Before calling change function,
qdisc_change() ensures tca[TCA_OPTIONS] is not empty. The other way is
that .init() will call it. The opt parameter is also checked before
calling change function in .init(). Therefore, it's no need to check the
input parameter opt in change function.

Signed-off-by: Zhengchao Shao 
Acked-by: Toke Høiland-Jørgensen 
Link: https://lore.kernel.org/r/20220829071219.208646-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni

net: sched: delete duplicate cleanup of backlog and qlen

2022-08-25T13:10:17+00:00

qdisc_reset() is clearing qdisc->q.qlen and qdisc->qstats.backlog
_after_ calling qdisc->ops->reset. There is no need to clear them
again in the specific reset function.

Signed-off-by: Zhengchao Shao 
Link: https://lore.kernel.org/r/20220824005231.345727-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni

fq_codel: generalise ce_threshold marking for subset of traffic

2021-10-20T22:24:36+00:00

Commit e72aeb9ee0e3 ("fq_codel: implement L4S style ce_threshold_ect1
marking") expanded the ce_threshold feature of FQ-CoDel so it can
be applied to a subset of the traffic, using the ECT(1) bit of the ECN
field as the classifier. However, hard-coding ECT(1) as the only
classifier for this feature seems limiting, so let's expand it to be more
general.

To this end, change the parameter from a ce_threshold_ect1 boolean, to a
one-byte selector/mask pair (ce_threshold_{selector,mask}) which is applied
to the whole diffserv/ECN field in the IP header. This makes it possible to
classify packets by any value in either the ECN field or the diffserv
field. In particular, setting a selector of INET_ECN_ECT_1 and a mask of
INET_ECN_MASK corresponds to the functionality before this patch, and a
mask of ~INET_ECN_MASK allows using the selector as a straight-forward
match against a diffserv code point:

 # apply ce_threshold to ECT(1) traffic
 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x1/0x3

 # apply ce_threshold to ECN-capable traffic marked as diffserv AF22
 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x50/0xfc

Regardless of the selector chosen, the normal rules for ECN-marking of
packets still apply, i.e., the flow must still declare itself ECN-capable
by setting one of the bits in the ECN field to get marked at all.

v2:
- Add tc usage examples to patch description

Signed-off-by: Toke Høiland-Jørgensen 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20211019174709.69081-1-toke@redhat.com
Signed-off-by: Jakub Kicinski

fq_codel: implement L4S style ce_threshold_ect1 marking

2021-10-15T10:33:08+00:00

Add TCA_FQ_CODEL_CE_THRESHOLD_ECT1 boolean option to select Low Latency,
Low Loss, Scalable Throughput (L4S) style marking, along with ce_threshold.

If enabled, only packets with ECT(1) can be transformed to CE
if their sojourn time is above the ce_threshold.

Note that this new option does not change rules for codel law.
In particular, if TCA_FQ_CODEL_ECN is left enabled (this is
the default when fq_codel qdisc is created), ECT(0) packets can
still get CE if codel law (as governed by limit/target) decides so.

Section 4.3.b of current draft [1] states:

b.  A scheduler with per-flow queues such as FQ-CoDel or FQ-PIE can
    be used for L4S.  For instance within each queue of an FQ-CoDel
    system, as well as a CoDel AQM, there is typically also ECN
    marking at an immediate (unsmoothed) shallow threshold to support
    use in data centres (see Sec.5.2.7 of [RFC8290]).  This can be
    modified so that the shallow threshold is solely applied to
    ECT(1) packets.  Then if there is a flow of non-ECN or ECT(0)
    packets in the per-flow-queue, the Classic AQM (e.g.  CoDel) is
    applied; while if there is a flow of ECT(1) packets in the queue,
    the shallower (typically sub-millisecond) threshold is applied.

Tested:

tc qd replace dev eth1 root fq_codel ce_threshold_ect1 50usec

netperf ... -t TCP_STREAM -- K dctcp

tc -s -d qd sh dev eth1
qdisc fq_codel 8022: root refcnt 32 limit 10240p flows 1024 quantum 9212 target 5ms ce_threshold_ect1 49us interval 100ms memory_limit 32Mb ecn drop_batch 64
 Sent 14388596616 bytes 9543449 pkt (dropped 0, overlimits 0 requeues 152013)
 backlog 0b 0p requeues 152013
  maxpacket 68130 drop_overlimit 0 new_flow_count 95678 ecn_mark 0 ce_mark 7639
  new_flows_len 0 old_flows_len 0

[1] L4S current draft:
https://datatracker.ietf.org/doc/html/draft-ietf-tsvwg-l4s-arch

Signed-off-by: Eric Dumazet 
Cc: Neal Cardwell 
Cc: Ingemar Johansson S 
Cc: Tom Henderson 
Cc: Bob Briscoe 
Signed-off-by: David S. Miller

fq_codel: reject silly quantum parameters

2021-09-04T09:49:46+00:00

syzbot found that forcing a big quantum attribute would crash hosts fast,
essentially using this:

tc qd replace dev eth0 root fq_codel quantum 4294967295

This is because fq_codel_dequeue() would have to loop
~2^31 times in :

	if (flow->deficit <= 0) {
		flow->deficit += q->quantum;
		list_move_tail(&flow->flowchain, &q->old_flows);
		goto begin;
	}

SFQ max quantum is 2^19 (half a megabyte)
Lets adopt a max quantum of one megabyte for FQ_CODEL.

Fixes: 4b549a2ef4be ("fq_codel: Fair Queue Codel AQM")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot 
Signed-off-by: David S. Miller