Changes in v2:
It was requested to add test cases for the taprio software and offload modes.
Those are patches 08 and 09.
That implies adding taprio offload support to netdevsim, which is patch 07.
In turn, that implies adding a PHC driver for netdevsim, which is patch 06.
v1 at:
https://lore.kernel.org/lkml/[email protected]/
Original message:
Prompted by Vinicius' request to consolidate some child Qdisc
dereferences in taprio:
https://lore.kernel.org/netdev/[email protected]/
I remembered that I had left some unfinished work in this Qdisc, namely
commit af7b29b1deaa ("Revert "net/sched: taprio: make qdisc_leaf() see
the per-netdev-queue pfifo child qdiscs"").
This patch set represents another stab at, essentially, what's in the
title. Not only does taprio not properly detect when it's grafted as a
non-root qdisc, but it also returns incorrect per-class stats.
Eventually, Vinicius' request is addressed too, although in a different
form than the one he requested (which was purely cosmetic).
Review from people more experienced with Qdiscs than me would be
appreciated. I tried my best to explain what I consider to be problems.
I am deliberately targeting net-next because the changes are too
invasive for net - they were reverted from stable once already.
Vladimir Oltean (9):
net/sched: taprio: don't access q->qdiscs[] in unoffloaded mode during
attach()
net/sched: taprio: keep child Qdisc refcount elevated at 2 in offload
mode
net/sched: taprio: try again to report q->qdiscs[] to qdisc_leaf()
net/sched: taprio: delete misleading comment about preallocating child
qdiscs
net/sched: taprio: dump class stats for the actual q->qdiscs[]
net: netdevsim: create a mock-up PTP Hardware Clock driver
net: netdevsim: mimic tc-taprio offload
selftests/tc-testing: test that taprio can only be attached as root
selftests/tc-testing: verify that a qdisc can be grafted onto a taprio
class
drivers/net/Kconfig | 1 +
drivers/net/netdevsim/ethtool.c | 11 ++
drivers/net/netdevsim/netdev.c | 38 +++-
drivers/net/netdevsim/netdevsim.h | 2 +
drivers/ptp/Kconfig | 11 ++
drivers/ptp/Makefile | 1 +
drivers/ptp/ptp_mock.c | 175 ++++++++++++++++++
include/linux/ptp_mock.h | 38 ++++
net/sched/sch_taprio.c | 68 ++++---
.../tc-testing/tc-tests/qdiscs/taprio.json | 98 ++++++++++
10 files changed, 415 insertions(+), 28 deletions(-)
create mode 100644 drivers/ptp/ptp_mock.c
create mode 100644 include/linux/ptp_mock.h
--
2.34.1
As mentioned in commit af7b29b1deaa ("Revert "net/sched: taprio: make
qdisc_leaf() see the per-netdev-queue pfifo child qdiscs"") - unlike
mqprio, taprio doesn't use q->qdiscs[] only as a temporary transport
between Qdisc_ops :: init() and Qdisc_ops :: attach().
Delete the comment, which is just stolen from mqprio, but there, the
usage patterns are a lot different, and this is nothing but confusing.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2: none
net/sched/sch_taprio.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 14d628926d61..c35e27d0e49e 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2085,11 +2085,8 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
return -EOPNOTSUPP;
}
- /* pre-allocate qdisc, attachment can't fail */
- q->qdiscs = kcalloc(dev->num_tx_queues,
- sizeof(q->qdiscs[0]),
+ q->qdiscs = kcalloc(dev->num_tx_queues, sizeof(q->qdiscs[0]),
GFP_KERNEL);
-
if (!q->qdiscs)
return -ENOMEM;
--
2.34.1
This is a simple code transformation with no intended behavior change,
just to make it absolutely clear that q->qdiscs[] is only attached to
the child taprio classes in full offload mode.
Right now we use the q->qdiscs[] variable in taprio_attach() for
software mode too, but that is quite confusing and avoidable. We use
it only to reach the netdev TX queue, but we could as well just use
netdev_get_tx_queue() for that.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2: none
net/sched/sch_taprio.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index c6627f5abdfa..3ee8a7cca786 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2131,14 +2131,20 @@ static void taprio_attach(struct Qdisc *sch)
/* Attach underlying qdisc */
for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
- struct Qdisc *qdisc = q->qdiscs[ntx];
+ struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, ntx);
struct Qdisc *old;
if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
+ struct Qdisc *qdisc = q->qdiscs[ntx];
+
qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
- old = dev_graft_qdisc(qdisc->dev_queue, qdisc);
+ old = dev_graft_qdisc(dev_queue, qdisc);
} else {
- old = dev_graft_qdisc(qdisc->dev_queue, sch);
+ /* In software mode, attach the root taprio qdisc
+ * to all netdev TX queues, so that dev_qdisc_enqueue()
+ * goes through taprio_enqueue().
+ */
+ old = dev_graft_qdisc(dev_queue, sch);
qdisc_refcount_inc(sch);
}
if (old)
--
2.34.1
Normally, Qdiscs have one reference on them held by their owner and one
held for each TXQ to which they are attached, however this is not the
case with the children of an offloaded taprio. Instead, the taprio qdisc
currently lives in the following fragile equilibrium.
In the software scheduling case, taprio attaches itself (the root Qdisc)
to all TXQs, thus having a refcount of 1 + the number of TX queues. In
this mode, the q->qdiscs[] children are not visible directly to the
Qdisc API. The lifetime of the Qdiscs from this private array lasts
until qdisc_destroy() -> taprio_destroy().
In the fully offloaded case, the root taprio has a refcount of 1, and
all child q->qdiscs[] also have a refcount of 1. The child q->qdiscs[]
are attached to the netdev TXQs directly and thus are visible to the
Qdisc API, however taprio loses a reference to them very early - during
qdisc_graft(parent==NULL) -> taprio_attach(). At that time, taprio frees
the q->qdiscs[] array to not leak memory, but interestingly, it does not
release a reference on these qdiscs because it doesn't effectively own
them - they are created by taprio but owned by the Qdisc core, and will
be freed by qdisc_graft(parent==NULL, new==NULL) -> qdisc_put(old) when
the Qdisc is deleted or when the child Qdisc is replaced with something
else.
My interest is to change this equilibrium such that taprio also owns a
reference on the q->qdiscs[] child Qdiscs for the lifetime of the root
Qdisc, including in full offload mode. I want this because I would like
taprio_leaf(), taprio_dump_class(), taprio_dump_class_stats() to have
insight into q->qdiscs[] for the software scheduling mode - currently
they look at dev_queue->qdisc_sleeping, which is, as mentioned, the same
as the root taprio.
The following set of changes is necessary:
- don't free q->qdiscs[] early in taprio_attach(), free it late in
taprio_destroy() for consistency with software mode. But:
- currently that's not possible, because taprio doesn't own a reference
on q->qdiscs[]. So hold that reference - once during the initial
attach() and once during subsequent graft() calls when the child is
changed.
- always keep track of the current child in q->qdiscs[], even for full
offload mode, so that we free in taprio_destroy() what we should, and
not something stale.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2:
- fix refcount not dropping to 0 after a graft operation - spotted by
Paolo
- slightly reword commit message and comments
net/sched/sch_taprio.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 3ee8a7cca786..b5f533914415 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2132,30 +2132,31 @@ static void taprio_attach(struct Qdisc *sch)
/* Attach underlying qdisc */
for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, ntx);
- struct Qdisc *old;
+ struct Qdisc *old, *dev_queue_qdisc;
if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
struct Qdisc *qdisc = q->qdiscs[ntx];
+ /* In offload mode, the root taprio qdisc is bypassed
+ * and the netdev TX queues see the children directly
+ */
qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
- old = dev_graft_qdisc(dev_queue, qdisc);
+ dev_queue_qdisc = qdisc;
} else {
/* In software mode, attach the root taprio qdisc
* to all netdev TX queues, so that dev_qdisc_enqueue()
* goes through taprio_enqueue().
*/
- old = dev_graft_qdisc(dev_queue, sch);
- qdisc_refcount_inc(sch);
+ dev_queue_qdisc = sch;
}
+ old = dev_graft_qdisc(dev_queue, dev_queue_qdisc);
+ /* The qdisc's refcount requires to be elevated once
+ * for each netdev TX queue it is grafted onto
+ */
+ qdisc_refcount_inc(dev_queue_qdisc);
if (old)
qdisc_put(old);
}
-
- /* access to the child qdiscs is not needed in offload mode */
- if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
- kfree(q->qdiscs);
- q->qdiscs = NULL;
- }
}
static struct netdev_queue *taprio_queue_get(struct Qdisc *sch,
@@ -2184,13 +2185,23 @@ static int taprio_graft(struct Qdisc *sch, unsigned long cl,
if (dev->flags & IFF_UP)
dev_deactivate(dev);
+ /* In offload mode, the child Qdisc is directly attached to the netdev
+ * TX queue, and thus, we need to keep its refcount elevated in order
+ * to counteract qdisc_graft()'s call to qdisc_put() once per TX queue.
+ * However, save the reference to the new qdisc in the private array in
+ * both software and offload cases, to have an up-to-date reference to
+ * our children.
+ */
+ *old = q->qdiscs[cl - 1];
if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
- *old = dev_graft_qdisc(dev_queue, new);
- } else {
- *old = q->qdiscs[cl - 1];
- q->qdiscs[cl - 1] = new;
+ WARN_ON_ONCE(dev_graft_qdisc(dev_queue, new) != *old);
+ if (new)
+ qdisc_refcount_inc(new);
+ if (*old)
+ qdisc_put(*old);
}
+ q->qdiscs[cl - 1] = new;
if (new)
new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
--
2.34.1
This makes a difference for the software scheduling mode, where
dev_queue->qdisc_sleeping is the same as the taprio root Qdisc itself,
but when we're talking about what Qdisc and stats get reported for a
traffic class, the root taprio isn't what comes to mind, but q->qdiscs[]
is.
To understand the difference, I've attempted to send 100 packets in
software mode through class 8001:5, and recorded the stats before and
after the change.
Here is before:
$ tc -s class show dev eth0
class taprio 8001:1 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:2 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:3 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:4 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:5 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:6 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:7 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:8 root leaf 8001:
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
and here is after:
class taprio 8001:1 root
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:2 root
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:3 root
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:4 root
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:5 root
Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:6 root
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:7 root
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
class taprio 8001:8 root leaf 800d:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
window_drops 0
The most glaring (and expected) difference is that before, all class
stats reported the global stats, whereas now, they really report just
the counters for that traffic class.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2:
- reword commit message
- rebase on top of the TAPRIO_CMD_TC_STATS -> TAPRIO_CMD_QUEUE_STATS change
net/sched/sch_taprio.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index c35e27d0e49e..86450e67be14 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2458,11 +2458,11 @@ static unsigned long taprio_find(struct Qdisc *sch, u32 classid)
static int taprio_dump_class(struct Qdisc *sch, unsigned long cl,
struct sk_buff *skb, struct tcmsg *tcm)
{
- struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
+ struct Qdisc *child = taprio_leaf(sch, cl);
tcm->tcm_parent = TC_H_ROOT;
tcm->tcm_handle |= TC_H_MIN(cl);
- tcm->tcm_info = rtnl_dereference(dev_queue->qdisc_sleeping)->handle;
+ tcm->tcm_info = child->handle;
return 0;
}
@@ -2472,16 +2472,14 @@ static int taprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
__releases(d->lock)
__acquires(d->lock)
{
- struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
+ struct Qdisc *child = taprio_leaf(sch, cl);
struct tc_taprio_qopt_offload offload = {
.cmd = TAPRIO_CMD_QUEUE_STATS,
.queue_stats = {
.queue = cl - 1,
},
};
- struct Qdisc *child;
- child = rtnl_dereference(dev_queue->qdisc_sleeping);
if (gnet_stats_copy_basic(d, NULL, &child->bstats, true) < 0 ||
qdisc_qstats_copy(d, child) < 0)
return -1;
--
2.34.1
Check that the "Can only be attached as root qdisc" error message from
taprio is effective by attempting to attach it to a class of another
taprio qdisc. That operation should fail.
In the bug that was squashed by change "net/sched: taprio: try again to
report q->qdiscs[] to qdisc_leaf()", grafting a child taprio to a root
software taprio would be misinterpreted as a change() to the root
taprio. Catch this by looking at whether the base-time of the root
taprio has changed to follow the base-time of the child taprio,
something which should have absolutely never happened assuming correct
semantics.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2: patch is new
.../tc-testing/tc-tests/qdiscs/taprio.json | 48 +++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
index a44455372646..58d4d97f4499 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
@@ -131,5 +131,53 @@
"teardown": [
"echo \"1\" > /sys/bus/netdevsim/del_device"
]
+ },
+ {
+ "id": "39b4",
+ "name": "Reject grafting taprio as child qdisc of software taprio",
+ "category": [
+ "qdisc",
+ "taprio"
+ ],
+ "plugins": {
+ "requires": "nsPlugin"
+ },
+ "setup": [
+ "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
+ "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 clockid CLOCK_TAI"
+ ],
+ "cmdUnderTest": "$TC qdisc replace dev $ETH parent 8001:7 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 200 sched-entry S ff 20000000 clockid CLOCK_TAI",
+ "expExitCode": "2",
+ "verifyCmd": "$TC -j qdisc show dev $ETH root | jq '.[].options.base_time'",
+ "matchPattern": "0",
+ "matchCount": "1",
+ "teardown": [
+ "$TC qdisc del dev $ETH root",
+ "echo \"1\" > /sys/bus/netdevsim/del_device"
+ ]
+ },
+ {
+ "id": "e8a1",
+ "name": "Reject grafting taprio as child qdisc of offloaded taprio",
+ "category": [
+ "qdisc",
+ "taprio"
+ ],
+ "plugins": {
+ "requires": "nsPlugin"
+ },
+ "setup": [
+ "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
+ "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 flags 0x2"
+ ],
+ "cmdUnderTest": "$TC qdisc replace dev $ETH parent 8001:7 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 200 sched-entry S ff 20000000 flags 0x2",
+ "expExitCode": "2",
+ "verifyCmd": "$TC -j qdisc show dev $ETH root | jq '.[].options.base_time'",
+ "matchPattern": "0",
+ "matchCount": "1",
+ "teardown": [
+ "$TC qdisc del dev $ETH root",
+ "echo \"1\" > /sys/bus/netdevsim/del_device"
+ ]
}
]
--
2.34.1
The reason behind commit af7b29b1deaa ("Revert "net/sched: taprio: make
qdisc_leaf() see the per-netdev-queue pfifo child qdiscs"") was that the
patch it reverted caused a crash when attaching a CBS shaper to one of
the taprio classes. Prevent that from happening again by adding a test
case for it, which now passes correctly in both offload and software
modes.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2: patch is new
.../tc-testing/tc-tests/qdiscs/taprio.json | 50 +++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
index 58d4d97f4499..47692335bcf1 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
@@ -179,5 +179,55 @@
"$TC qdisc del dev $ETH root",
"echo \"1\" > /sys/bus/netdevsim/del_device"
]
+ },
+ {
+ "id": "a7bf",
+ "name": "Graft cbs as child of software taprio",
+ "category": [
+ "qdisc",
+ "taprio",
+ "cbs"
+ ],
+ "plugins": {
+ "requires": "nsPlugin"
+ },
+ "setup": [
+ "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
+ "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 clockid CLOCK_TAI"
+ ],
+ "cmdUnderTest": "$TC qdisc replace dev $ETH handle 8002: parent 8001:8 cbs idleslope 20000 sendslope -980000 hicredit 30 locredit -1470",
+ "expExitCode": "0",
+ "verifyCmd": "$TC -d qdisc show dev $ETH",
+ "matchPattern": "qdisc cbs 8002: parent 8001:8 hicredit 30 locredit -1470 sendslope -980000 idleslope 20000 offload 0",
+ "matchCount": "1",
+ "teardown": [
+ "$TC qdisc del dev $ETH root",
+ "echo \"1\" > /sys/bus/netdevsim/del_device"
+ ]
+ },
+ {
+ "id": "6a83",
+ "name": "Graft cbs as child of offloaded taprio",
+ "category": [
+ "qdisc",
+ "taprio",
+ "cbs"
+ ],
+ "plugins": {
+ "requires": "nsPlugin"
+ },
+ "setup": [
+ "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
+ "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 flags 0x2"
+ ],
+ "cmdUnderTest": "$TC qdisc replace dev $ETH handle 8002: parent 8001:8 cbs idleslope 20000 sendslope -980000 hicredit 30 locredit -1470",
+ "expExitCode": "0",
+ "verifyCmd": "$TC -d qdisc show dev $ETH",
+ "matchPattern": "qdisc cbs 8002: parent 8001:8 hicredit 30 locredit -1470 sendslope -980000 idleslope 20000 offload 0",
+ "matchCount": "1",
+ "teardown": [
+ "$TC qdisc del dev $ETH root",
+ "echo \"1\" > /sys/bus/netdevsim/del_device"
+ ]
}
]
--
2.34.1
On 13/06/2023 18:54, Vladimir Oltean wrote:
> Check that the "Can only be attached as root qdisc" error message from
> taprio is effective by attempting to attach it to a class of another
> taprio qdisc. That operation should fail.
>
> In the bug that was squashed by change "net/sched: taprio: try again to
> report q->qdiscs[] to qdisc_leaf()", grafting a child taprio to a root
> software taprio would be misinterpreted as a change() to the root
> taprio. Catch this by looking at whether the base-time of the root
> taprio has changed to follow the base-time of the child taprio,
> something which should have absolutely never happened assuming correct
> semantics.
>
> Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Pedro Tammela <[email protected]>
> ---
> v1->v2: patch is new
>
> .../tc-testing/tc-tests/qdiscs/taprio.json | 48 +++++++++++++++++++
> 1 file changed, 48 insertions(+)
>
> diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
> index a44455372646..58d4d97f4499 100644
> --- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
> +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
> @@ -131,5 +131,53 @@
> "teardown": [
> "echo \"1\" > /sys/bus/netdevsim/del_device"
> ]
> + },
> + {
> + "id": "39b4",
> + "name": "Reject grafting taprio as child qdisc of software taprio",
> + "category": [
> + "qdisc",
> + "taprio"
> + ],
> + "plugins": {
> + "requires": "nsPlugin"
> + },
> + "setup": [
> + "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
> + "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 clockid CLOCK_TAI"
> + ],
> + "cmdUnderTest": "$TC qdisc replace dev $ETH parent 8001:7 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 200 sched-entry S ff 20000000 clockid CLOCK_TAI",
> + "expExitCode": "2",
> + "verifyCmd": "$TC -j qdisc show dev $ETH root | jq '.[].options.base_time'",
> + "matchPattern": "0",
> + "matchCount": "1",
> + "teardown": [
> + "$TC qdisc del dev $ETH root",
> + "echo \"1\" > /sys/bus/netdevsim/del_device"
> + ]
> + },
> + {
> + "id": "e8a1",
> + "name": "Reject grafting taprio as child qdisc of offloaded taprio",
> + "category": [
> + "qdisc",
> + "taprio"
> + ],
> + "plugins": {
> + "requires": "nsPlugin"
> + },
> + "setup": [
> + "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
> + "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 flags 0x2"
> + ],
> + "cmdUnderTest": "$TC qdisc replace dev $ETH parent 8001:7 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 200 sched-entry S ff 20000000 flags 0x2",
> + "expExitCode": "2",
> + "verifyCmd": "$TC -j qdisc show dev $ETH root | jq '.[].options.base_time'",
> + "matchPattern": "0",
> + "matchCount": "1",
> + "teardown": [
> + "$TC qdisc del dev $ETH root",
> + "echo \"1\" > /sys/bus/netdevsim/del_device"
> + ]
> }
> ]
On 13/06/2023 18:54, Vladimir Oltean wrote:
> The reason behind commit af7b29b1deaa ("Revert "net/sched: taprio: make
> qdisc_leaf() see the per-netdev-queue pfifo child qdiscs"") was that the
> patch it reverted caused a crash when attaching a CBS shaper to one of
> the taprio classes. Prevent that from happening again by adding a test
> case for it, which now passes correctly in both offload and software
> modes.
>
> Signed-off-by: Vladimir Oltean <[email protected]>
Other than the comment below,
Reviewed-by: Pedro Tammela <[email protected]>
> ---
> v1->v2: patch is new
>
> .../tc-testing/tc-tests/qdiscs/taprio.json | 50 +++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
> index 58d4d97f4499..47692335bcf1 100644
> --- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
> +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
> @@ -179,5 +179,55 @@
> "$TC qdisc del dev $ETH root",
> "echo \"1\" > /sys/bus/netdevsim/del_device"
> ]
> + },
> + {
> + "id": "a7bf",
> + "name": "Graft cbs as child of software taprio",
> + "category": [
> + "qdisc",
> + "taprio",
> + "cbs"
> + ],
> + "plugins": {
> + "requires": "nsPlugin"
> + },
> + "setup": [
> + "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
> + "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 clockid CLOCK_TAI"
> + ],
> + "cmdUnderTest": "$TC qdisc replace dev $ETH handle 8002: parent 8001:8 cbs idleslope 20000 sendslope -980000 hicredit 30 locredit -1470",
> + "expExitCode": "0",
> + "verifyCmd": "$TC -d qdisc show dev $ETH",
> + "matchPattern": "qdisc cbs 8002: parent 8001:8 hicredit 30 locredit -1470 sendslope -980000 idleslope 20000 offload 0",
> + "matchCount": "1",
> + "teardown": [
> + "$TC qdisc del dev $ETH root",
> + "echo \"1\" > /sys/bus/netdevsim/del_device"
> + ]
> + },
> + {
> + "id": "6a83",
> + "name": "Graft cbs as child of offloaded taprio",
> + "category": [
> + "qdisc",
> + "taprio",
> + "cbs"
> + ],
> + "plugins": {
> + "requires": "nsPlugin"
> + },
> + "setup": [
> + "echo \"1 1 8\" > /sys/bus/netdevsim/new_device",
> + "$TC qdisc replace dev $ETH handle 8001: parent root stab overhead 24 taprio num_tc 8 map 0 1 2 3 4 5 6 7 queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 sched-entry S ff 20000000 flags 0x2"
> + ],
> + "cmdUnderTest": "$TC qdisc replace dev $ETH handle 8002: parent 8001:8 cbs idleslope 20000 sendslope -980000 hicredit 30 locredit -1470",
> + "expExitCode": "0",
> + "verifyCmd": "$TC -d qdisc show dev $ETH",
> + "matchPattern": "qdisc cbs 8002: parent 8001:8 hicredit 30 locredit -1470 sendslope -980000 idleslope 20000 offload 0",
Seems like this test is missing the 'refcnt 2' in the match pattern
> + "matchCount": "1",
> + "teardown": [
> + "$TC qdisc del dev $ETH root",
> + "echo \"1\" > /sys/bus/netdevsim/del_device"
> + ]
> }
> ]
On 13/06/2023 18:54, Vladimir Oltean wrote:
> [...]
Hi Vladimir,
Thanks for adding the tdc tests.
This series seem to have broken test 8471 in taprio but I don't see it
fixed here.
Do you plan to fix it in another patch?
On Wed, Jun 14, 2023 at 01:45:42PM -0300, Pedro Tammela wrote:
> > + "cmdUnderTest": "$TC qdisc replace dev $ETH handle 8002: parent 8001:8 cbs idleslope 20000 sendslope -980000 hicredit 30 locredit -1470",
> > + "expExitCode": "0",
> > + "verifyCmd": "$TC -d qdisc show dev $ETH",
> > + "matchPattern": "qdisc cbs 8002: parent 8001:8 hicredit 30 locredit -1470 sendslope -980000 idleslope 20000 offload 0",
>
> Seems like this test is missing the 'refcnt 2' in the match pattern
Makes sense. This is consistent with the idea of my patch set, which is
that in offloaded taprio mode, each child Qdisc has a refcount elevated
by the fact that it's attached to a netdev TX queue (hence the 2 here).
I had copied this expected output from the "Graft cbs as child of software
taprio" test a7bf (not sure why I didn't catch the failure), but there,
the expected refcount of child Qdiscs is 1 (and thus, not shown).
On Wed, Jun 14, 2023 at 01:47:25PM -0300, Pedro Tammela wrote:
> On 13/06/2023 18:54, Vladimir Oltean wrote:
> > [...]
>
> Hi Vladimir,
> Thanks for adding the tdc tests.
> This series seem to have broken test 8471 in taprio but I don't see it fixed
> here.
> Do you plan to fix it in another patch?
>
Thanks for pointing it out. I'll be unbreaking it in the next version,
as part of the patch that changes the "tc class show" output.