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Merge branch 'sch_sfq-derived-limit'

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Octavian Purdila says:

====================
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.

v3:
 - remove a couple of unnecessary comments
 - rearrange local variables to use reverse Christmas tree style
   declaration order

v2: https://lore.kernel.org/all/20250402162750.1671155-1-tavip@google.com/
 - remove tmp struct and directly use local variables

v1: https://lore.kernel.org/all/20250328201634.3876474-1-tavip@google.com/
===================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2025-04-09 12:55:48 +01:00
parent 7f1ff1b38a 26e705184e
commit 29d261466f
2 changed files with 86 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

66
net/sched/sch_sfq.c
View File

@@ -631,6 +631,15 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt,
struct red_parms *p = NULL;
struct sk_buff *to_free = NULL;
struct sk_buff *tail = NULL;
unsigned int maxflows;
unsigned int quantum;
unsigned int divisor;
int perturb_period;
u8 headdrop;
u8 maxdepth;
int limit;
u8 flags;
if (opt->nla_len < nla_attr_size(sizeof(*ctl)))
return -EINVAL;
@@ -652,39 +661,64 @@ 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);
limit = q->limit;
divisor = q->divisor;
headdrop = q->headdrop;
maxdepth = q->maxdepth;
maxflows = q->maxflows;
perturb_period = q->perturb_period;
quantum = q->quantum;
flags = q->flags;
/* update and validate configuration */
if (ctl->quantum)
q->quantum = ctl->quantum;
WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ);
quantum = ctl->quantum;
perturb_period = ctl->perturb_period * HZ;
if (ctl->flows)
q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
if (ctl->divisor) {
q->divisor = ctl->divisor;
q->maxflows = min_t(u32, q->maxflows, q->divisor);
divisor = ctl->divisor;
maxflows = min_t(u32, maxflows, divisor);
}
if (ctl_v1) {
if (ctl_v1->depth)
q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);
maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH);
if (p) {
swap(q->red_parms, p);
red_set_parms(q->red_parms,
red_set_parms(p,
ctl_v1->qth_min, ctl_v1->qth_max,
ctl_v1->Wlog,
ctl_v1->Plog, ctl_v1->Scell_log,
NULL,
ctl_v1->max_P);
}
q->flags = ctl_v1->flags;
q->headdrop = ctl_v1->headdrop;
flags = ctl_v1->flags;
headdrop = ctl_v1->headdrop;
}
if (ctl->limit) {
q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows);
q->maxflows = min_t(u32, q->maxflows, q->limit);
limit = min_t(u32, ctl->limit, maxdepth * maxflows);
maxflows = min_t(u32, maxflows, limit);
}
if (limit == 1) {
sch_tree_unlock(sch);
kfree(p);
NL_SET_ERR_MSG_MOD(extack, "invalid limit");
return -EINVAL;
}
/* commit configuration */
q->limit = limit;
q->divisor = divisor;
q->headdrop = headdrop;
q->maxdepth = maxdepth;
q->maxflows = maxflows;
WRITE_ONCE(q->perturb_period, perturb_period);
q->quantum = quantum;
q->flags = flags;
if (p)
swap(q->red_parms, p);
qlen = sch->q.qlen;
while (sch->q.qlen > q->limit) {

36
tools/testing/selftests/tc-testing/tc-tests/qdiscs/sfq.json
View File

@@ -228,5 +228,41 @@
"matchCount": "0",
"teardown": [
]
},
{
"id": "7f8f",
"name": "Check that a derived limit of 1 is rejected (limit 2 depth 1 flows 1)",
"category": [
"qdisc",
"sfq"
],
"plugins": {
"requires": "nsPlugin"
},
"setup": [],
"cmdUnderTest": "$TC qdisc add dev $DUMMY handle 1: root sfq limit 2 depth 1 flows 1",
"expExitCode": "2",
"verifyCmd": "$TC qdisc show dev $DUMMY",
"matchPattern": "sfq",
"matchCount": "0",
"teardown": []
},
{
"id": "5168",
"name": "Check that a derived limit of 1 is rejected (limit 2 depth 1 divisor 1)",
"category": [
"qdisc",
"sfq"
],
"plugins": {
"requires": "nsPlugin"
},
"setup": [],
"cmdUnderTest": "$TC qdisc add dev $DUMMY handle 1: root sfq limit 2 depth 1 divisor 1",
"expExitCode": "2",
"verifyCmd": "$TC qdisc show dev $DUMMY",
"matchPattern": "sfq",
"matchCount": "0",
"teardown": []
}
]