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Date: Fri, 15 Dec 2023 19:12:18 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Jamal Hadi Salim <hadi@...atatu.com>
Cc: Victor Nogueira <victor@...atatu.com>, jhs@...atatu.com,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, xiyou.wangcong@...il.com, mleitner@...hat.com,
vladbu@...dia.com, paulb@...dia.com, pctammela@...atatu.com,
netdev@...r.kernel.org, kernel@...atatu.com
Subject: Re: [PATCH net-next v7 1/3] net/sched: Introduce tc block netdev
tracking infra
Fri, Dec 15, 2023 at 06:17:27PM CET, hadi@...atatu.com wrote:
>On Fri, Dec 15, 2023 at 10:52 AM Jiri Pirko <jiri@...nulli.us> wrote:
>>
>> Fri, Dec 15, 2023 at 03:35:01PM CET, hadi@...atatu.com wrote:
>> >On Fri, Dec 15, 2023 at 8:31 AM Jiri Pirko <jiri@...nulli.us> wrote:
>> >>
>> >> Fri, Dec 15, 2023 at 12:10:48PM CET, victor@...atatu.com wrote:
>> >> >This commit makes tc blocks track which ports have been added to them.
>> >> >And, with that, we'll be able to use this new information to send
>> >> >packets to the block's ports. Which will be done in the patch #3 of this
>> >> >series.
>> >> >
>> >> >Suggested-by: Jiri Pirko <jiri@...dia.com>
>> >> >Co-developed-by: Jamal Hadi Salim <jhs@...atatu.com>
>> >> >Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
>> >> >Co-developed-by: Pedro Tammela <pctammela@...atatu.com>
>> >> >Signed-off-by: Pedro Tammela <pctammela@...atatu.com>
>> >> >Signed-off-by: Victor Nogueira <victor@...atatu.com>
>> >> >---
>> >> > include/net/sch_generic.h | 4 +++
>> >> > net/sched/cls_api.c | 2 ++
>> >> > net/sched/sch_api.c | 55 +++++++++++++++++++++++++++++++++++++++
>> >> > net/sched/sch_generic.c | 31 ++++++++++++++++++++--
>> >> > 4 files changed, 90 insertions(+), 2 deletions(-)
>> >> >
>> >> >diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
>> >> >index dcb9160e6467..cefca55dd4f9 100644
>> >> >--- a/include/net/sch_generic.h
>> >> >+++ b/include/net/sch_generic.h
>> >> >@@ -19,6 +19,7 @@
>> >> > #include <net/gen_stats.h>
>> >> > #include <net/rtnetlink.h>
>> >> > #include <net/flow_offload.h>
>> >> >+#include <linux/xarray.h>
>> >> >
>> >> > struct Qdisc_ops;
>> >> > struct qdisc_walker;
>> >> >@@ -126,6 +127,8 @@ struct Qdisc {
>> >> >
>> >> > struct rcu_head rcu;
>> >> > netdevice_tracker dev_tracker;
>> >> >+ netdevice_tracker in_block_tracker;
>> >> >+ netdevice_tracker eg_block_tracker;
>> >> > /* private data */
>> >> > long privdata[] ____cacheline_aligned;
>> >> > };
>> >> >@@ -457,6 +460,7 @@ struct tcf_chain {
>> >> > };
>> >> >
>> >> > struct tcf_block {
>> >> >+ struct xarray ports; /* datapath accessible */
>> >> > /* Lock protects tcf_block and lifetime-management data of chains
>> >> > * attached to the block (refcnt, action_refcnt, explicitly_created).
>> >> > */
>> >> >diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>> >> >index dc1c19a25882..6020a32ecff2 100644
>> >> >--- a/net/sched/cls_api.c
>> >> >+++ b/net/sched/cls_api.c
>> >> >@@ -531,6 +531,7 @@ static void tcf_block_destroy(struct tcf_block *block)
>> >> > {
>> >> > mutex_destroy(&block->lock);
>> >> > mutex_destroy(&block->proto_destroy_lock);
>> >> >+ xa_destroy(&block->ports);
>> >> > kfree_rcu(block, rcu);
>> >> > }
>> >> >
>> >> >@@ -1002,6 +1003,7 @@ static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
>> >> > refcount_set(&block->refcnt, 1);
>> >> > block->net = net;
>> >> > block->index = block_index;
>> >> >+ xa_init(&block->ports);
>> >> >
>> >> > /* Don't store q pointer for blocks which are shared */
>> >> > if (!tcf_block_shared(block))
>> >> >diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
>> >> >index e9eaf637220e..09ec64f2f463 100644
>> >> >--- a/net/sched/sch_api.c
>> >> >+++ b/net/sched/sch_api.c
>> >> >@@ -1180,6 +1180,57 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
>> >> > return 0;
>> >> > }
>> >> >
>> >> >+static int qdisc_block_add_dev(struct Qdisc *sch, struct net_device *dev,
>> >> >+ struct nlattr **tca,
>> >> >+ struct netlink_ext_ack *extack)
>> >> >+{
>> >> >+ const struct Qdisc_class_ops *cl_ops = sch->ops->cl_ops;
>> >> >+ struct tcf_block *in_block = NULL;
>> >> >+ struct tcf_block *eg_block = NULL;
>> >>
>> >> No need to null.
>> >>
>> >> Can't you just have:
>> >> struct tcf_block *block;
>> >>
>> >> And use it in both ifs? You can easily obtain the block again on
>> >> the error path.
>> >>
>> >
>> >It's just easier to read.
>>
>> Hmm.
>>
>> >
>> >> >+ int err;
>> >> >+
>> >> >+ if (tca[TCA_INGRESS_BLOCK]) {
>> >> >+ /* works for both ingress and clsact */
>> >> >+ in_block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
>> >> >+ if (!in_block) {
>> >>
>> >> I don't see how this could happen. In fact, why exactly do you check
>> >> tca[TCA_INGRESS_BLOCK]?
>> >>
>> >
>> >It's lazy but what is wrong with doing that?
>>
>> It's not needed, that's wrong.
>>
>
>Are you ok with the proposal i made?
Not sure what you mean here.
>
>>
>> >
>> >> At this time, the clsact/ingress init() function was already called, you
>> >> can just do:
>> >>
>> >> block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
>> >> if (block) {
>> >> err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
>> >> if (err) {
>> >> NL_SET_ERR_MSG(extack, "Ingress block dev insert failed");
>> >> return err;
>> >> }
>> >> netdev_hold(dev, &sch->in_block_tracker, GFP_KERNEL);
>> >> }
>> >> block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
>> >> if (block) {
>> >> err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
>> >> if (err) {
>> >> NL_SET_ERR_MSG(extack, "Egress block dev insert failed");
>> >> goto err_out;
>> >> }
>> >> netdev_hold(dev, &sch->eg_block_tracker, GFP_KERNEL);
>> >> }
>> >> return 0;
>> >>
>> >> err_out:
>> >> block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
>> >> if (block) {
>> >> xa_erase(&block->ports, dev->ifindex);
>> >> netdev_put(dev, &sch->in_block_tracker);
>> >> }
>> >> return err;
>> >>
>> >> >+ NL_SET_ERR_MSG(extack, "Shared ingress block missing");
>> >> >+ return -EINVAL;
>> >> >+ }
>> >> >+
>> >> >+ err = xa_insert(&in_block->ports, dev->ifindex, dev, GFP_KERNEL);
>> >> >+ if (err) {
>> >> >+ NL_SET_ERR_MSG(extack, "Ingress block dev insert failed");
>> >> >+ return err;
>> >> >+ }
>> >> >+
>> >
>> >How about a middle ground:
>> > in_block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
>> > if (in_block) {
>> > err = xa_insert(&in_block->ports, dev->ifindex, dev,
>> >GFP_KERNEL);
>> > if (err) {
>> > NL_SET_ERR_MSG(extack, "ingress block dev
>> >insert failed");
>> > return err;
>> > }
>> > netdev_hold(dev, &sch->in_block_tracker, GFP_KERNEL)
>> > }
>> > eg_block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
>> > if (eg_block) {
>> > err = xa_insert(&eg_block->ports, dev->ifindex, dev,
>> >GFP_KERNEL);
>> > if (err) {
>> > netdev_put(dev, &sch->eg_block_tracker);
>> > NL_SET_ERR_MSG(extack, "Egress block dev
>> >insert failed");
>> > xa_erase(&in_block->ports, dev->ifindex);
>> > netdev_put(dev, &sch->in_block_tracker);
>> > return err;
>> > }
>> > netdev_hold(dev, &sch->eg_block_tracker, GFP_KERNEL);
>> > }
>> > return 0;
>> >
>> >> >+ netdev_hold(dev, &sch->in_block_tracker, GFP_KERNEL);
>> >>
>> >> Why exactly do you need an extra reference of netdev? Qdisc is already
>> >> having one.
>> >
>> >More fine grained tracking.
>>
>> Again, good for what exactly?
>
>We do xa_insert(&eg_block->ports, dev->ifindex, dev,...) which calls
>for a hold on the dev.
Why you need to take a reference for it exactly? You already hold a
reference for qdisc, why is that not enough?
>Then we need to track that for debugging; so, instead of incrementing
>the same qdisc tracker again for each of those inserts we keep a
>separate tracker.
>
>cheers,
>jamal
>
>>
>> >
>> >>
>> >> >+ }
>> >> >+
>> >> >+ if (tca[TCA_EGRESS_BLOCK]) {
>> >> >+ eg_block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
>> >> >+ if (!eg_block) {
>> >> >+ NL_SET_ERR_MSG(extack, "Shared egress block missing");
>> >> >+ err = -EINVAL;
>> >> >+ goto err_out;
>> >> >+ }
>> >> >+
>> >> >+ err = xa_insert(&eg_block->ports, dev->ifindex, dev, GFP_KERNEL);
>> >> >+ if (err) {
>> >> >+ NL_SET_ERR_MSG(extack, "Egress block dev insert failed");
>> >> >+ goto err_out;
>> >> >+ }
>> >> >+ netdev_hold(dev, &sch->eg_block_tracker, GFP_KERNEL);
>> >> >+ }
>> >> >+
>> >> >+ return 0;
>> >> >+err_out:
>> >> >+ if (in_block) {
>> >> >+ xa_erase(&in_block->ports, dev->ifindex);
>> >> >+ netdev_put(dev, &sch->in_block_tracker);
>> >> >+ }
>> >> >+ return err;
>> >> >+}
>> >> >+
>> >> > static int qdisc_block_indexes_set(struct Qdisc *sch, struct nlattr **tca,
>> >> > struct netlink_ext_ack *extack)
>> >> > {
>> >> >@@ -1350,6 +1401,10 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
>> >> > qdisc_hash_add(sch, false);
>> >> > trace_qdisc_create(ops, dev, parent);
>> >> >
>> >> >+ err = qdisc_block_add_dev(sch, dev, tca, extack);
>> >> >+ if (err)
>> >> >+ goto err_out4;
>> >> >+
>> >> > return sch;
>> >> >
>> >> > err_out4:
>> >> >diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
>> >> >index 8dd0e5925342..32bed60dea9f 100644
>> >> >--- a/net/sched/sch_generic.c
>> >> >+++ b/net/sched/sch_generic.c
>> >> >@@ -1050,7 +1050,11 @@ static void qdisc_free_cb(struct rcu_head *head)
>> >> >
>> >> > static void __qdisc_destroy(struct Qdisc *qdisc)
>> >> > {
>> >> >- const struct Qdisc_ops *ops = qdisc->ops;
>> >> >+ struct net_device *dev = qdisc_dev(qdisc);
>> >> >+ const struct Qdisc_ops *ops = qdisc->ops;
>> >> >+ const struct Qdisc_class_ops *cops;
>> >> >+ struct tcf_block *block;
>> >> >+ u32 block_index;
>> >> >
>> >> > #ifdef CONFIG_NET_SCHED
>> >> > qdisc_hash_del(qdisc);
>> >> >@@ -1061,11 +1065,34 @@ static void __qdisc_destroy(struct Qdisc *qdisc)
>> >> >
>> >> > qdisc_reset(qdisc);
>> >> >
>> >> >+ cops = ops->cl_ops;
>> >> >+ if (ops->ingress_block_get) {
>> >> >+ block_index = ops->ingress_block_get(qdisc);
>> >> >+ if (block_index) {
>> >>
>> >> I don't follow. What you need block_index for? Why can't you just call:
>> >> block = cops->tcf_block(qdisc, TC_H_MIN_INGRESS, NULL);
>> >> right away?
>> >
>> >Good point.
>> >
>> >cheers,
>> >jamal
>> >
>> >>
>> >> >+ block = cops->tcf_block(qdisc, TC_H_MIN_INGRESS, NULL);
>> >> >+ if (block) {
>> >> >+ if (xa_erase(&block->ports, dev->ifindex))
>> >> >+ netdev_put(dev, &qdisc->in_block_tracker);
>> >> >+ }
>> >> >+ }
>> >> >+ }
>> >> >+
>> >> >+ if (ops->egress_block_get) {
>> >> >+ block_index = ops->egress_block_get(qdisc);
>> >> >+ if (block_index) {
>> >> >+ block = cops->tcf_block(qdisc, TC_H_MIN_EGRESS, NULL);
>> >> >+ if (block) {
>> >> >+ if (xa_erase(&block->ports, dev->ifindex))
>> >> >+ netdev_put(dev, &qdisc->eg_block_tracker);
>> >> >+ }
>> >> >+ }
>> >> >+ }
>> >> >+
>> >> > if (ops->destroy)
>> >> > ops->destroy(qdisc);
>> >> >
>> >> > module_put(ops->owner);
>> >> >- netdev_put(qdisc_dev(qdisc), &qdisc->dev_tracker);
>> >> >+ netdev_put(dev, &qdisc->dev_tracker);
>> >> >
>> >> > trace_qdisc_destroy(qdisc);
>> >> >
>> >> >--
>> >> >2.25.1
>> >> >
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