Commit 1f62879e authored by Vladimir Oltean's avatar Vladimir Oltean Committed by David S. Miller
Browse files

net/sched: make stab available before ops->init() call 



Some qdiscs like taprio turn out to be actually pretty reliant on a well
configured stab, to not underestimate the skb transmission time (by
properly accounting for L1 overhead).

In a future change, taprio will need the stab, if configured by the
user, to be available at ops->init() time. It will become even more
important in upcoming work, when the overhead will be used for the
queueMaxSDU calculation that is passed to an offloading driver.

However, rcu_assign_pointer(sch->stab, stab) is called right after
ops->init(), making it unavailable, and I don't really see a good reason
for that.

Move it earlier, which nicely seems to simplify the error handling path
as well.

Signed-off-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: default avatarKurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a1e6ad30

net/sched/sch_api.c

+11 −18
Original line number Diff line number Diff line
@@ -1282,12 +1282,6 @@ static struct Qdisc *qdisc_create(struct net_device *dev, 
	if (err)

		goto err_out3;



	if (ops->init) {

		err = ops->init(sch, tca[TCA_OPTIONS], extack);

		if (err != 0)

			goto err_out5;

	}



	if (tca[TCA_STAB]) {

		stab = qdisc_get_stab(tca[TCA_STAB], extack);

		if (IS_ERR(stab)) {
@@ -1296,11 +1290,18 @@ static struct Qdisc *qdisc_create(struct net_device *dev, 
		}

		rcu_assign_pointer(sch->stab, stab);

	}



	if (ops->init) {

		err = ops->init(sch, tca[TCA_OPTIONS], extack);

		if (err != 0)

			goto err_out5;

	}



	if (tca[TCA_RATE]) {

		err = -EOPNOTSUPP;

		if (sch->flags & TCQ_F_MQROOT) {

			NL_SET_ERR_MSG(extack, "Cannot attach rate estimator to a multi-queue root qdisc");

			goto err_out4;

			goto err_out5;

		}



		err = gen_new_estimator(&sch->bstats,
@@ -1311,7 +1312,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev, 
					tca[TCA_RATE]);

		if (err) {

			NL_SET_ERR_MSG(extack, "Failed to generate new estimator");

			goto err_out4;

			goto err_out5;

		}

	}
@@ -1321,6 +1322,8 @@ static struct Qdisc *qdisc_create(struct net_device *dev, 
	return sch;



err_out5:

	qdisc_put_stab(rtnl_dereference(sch->stab));

err_out4:

	/* ops->init() failed, we call ->destroy() like qdisc_create_dflt() */

	if (ops->destroy)

		ops->destroy(sch);
@@ -1332,16 +1335,6 @@ static struct Qdisc *qdisc_create(struct net_device *dev, 
err_out:

	*errp = err;

	return NULL;



err_out4:

	/*

	 * Any broken qdiscs that would require a ops->reset() here?

	 * The qdisc was never in action so it shouldn't be necessary.

	 */

	qdisc_put_stab(rtnl_dereference(sch->stab));

	if (ops->destroy)

		ops->destroy(sch);

	goto err_out3;

}



static int qdisc_change(struct Qdisc *sch, struct nlattr **tca,