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sch_htb: Fix inconsistency when leaf qdisc creation fails

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In HTB offload mode, qdiscs of leaf classes are grafted to netdev
queues. sch_htb expects the dev_queue field of these qdiscs to point to
the corresponding queues. However, qdisc creation may fail, and in that
case noop_qdisc is used instead. Its dev_queue doesn't point to the
right queue, so sch_htb can lose track of used netdev queues, which will
cause internal inconsistencies.

This commit fixes this bug by keeping track of the netdev queue inside
struct htb_class. All reads of cl->leaf.q->dev_queue are replaced by the
new field, the two values are synced on writes, and WARNs are added to
assert equality of the two values.

The driver API has changed: when TC_HTB_LEAF_DEL needs to move a queue,
the driver used to pass the old and new queue IDs to sch_htb. Now that
there is a new field (offload_queue) in struct htb_class that needs to
be updated on this operation, the driver will pass the old class ID to
sch_htb instead (it already knows the new class ID).

Fixes: d03b195b5a ("sch_htb: Hierarchical QoS hardware offload")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20210826115425.1744053-1-maximmi@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Maxim Mikityanskiy 2021-08-26 14:54:25 +03:00 committed by Jakub Kicinski
parent 1b9fbe8130
commit ca49bfd90a
5 changed files with 72 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/net/ethernet/mellanox/mlx5/core/en/qos.c
View File

@ -733,8 +733,8 @@ static void mlx5e_reset_qdisc(struct net_device *dev, u16 qid)
spin_unlock_bh(qdisc_lock(qdisc));
}
int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 classid, u16 *old_qid,
u16 *new_qid, struct netlink_ext_ack *extack)
int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 *classid,
struct netlink_ext_ack *extack)
{
struct mlx5e_qos_node *node;
struct netdev_queue *txq;
@ -742,11 +742,9 @@ int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 classid, u16 *old_qid,
bool opened;
int err;
qos_dbg(priv->mdev, "TC_HTB_LEAF_DEL classid %04x\n", classid);
qos_dbg(priv->mdev, "TC_HTB_LEAF_DEL classid %04x\n", *classid);
*old_qid = *new_qid = 0;
node = mlx5e_sw_node_find(priv, classid);
node = mlx5e_sw_node_find(priv, *classid);
if (!node)
return -ENOENT;
@ -764,7 +762,7 @@ int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 classid, u16 *old_qid,
err = mlx5_qos_destroy_node(priv->mdev, node->hw_id);
if (err) /* Not fatal. */
qos_warn(priv->mdev, "Failed to destroy leaf node %u (class %04x), err = %d\n",
node->hw_id, classid, err);
node->hw_id, *classid, err);
mlx5e_sw_node_delete(priv, node);
@ -826,8 +824,7 @@ int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 classid, u16 *old_qid,
if (opened)
mlx5e_reactivate_qos_sq(priv, moved_qid, txq);
*old_qid = mlx5e_qid_from_qos(&priv->channels, moved_qid);
*new_qid = mlx5e_qid_from_qos(&priv->channels, qid);
*classid = node->classid;
return 0;
}

4
drivers/net/ethernet/mellanox/mlx5/core/en/qos.h
View File

@ -34,8 +34,8 @@ int mlx5e_htb_leaf_alloc_queue(struct mlx5e_priv *priv, u16 classid,
struct netlink_ext_ack *extack);
int mlx5e_htb_leaf_to_inner(struct mlx5e_priv *priv, u16 classid, u16 child_classid,
u64 rate, u64 ceil, struct netlink_ext_ack *extack);
int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 classid, u16 *old_qid,
u16 *new_qid, struct netlink_ext_ack *extack);
int mlx5e_htb_leaf_del(struct mlx5e_priv *priv, u16 *classid,
struct netlink_ext_ack *extack);
int mlx5e_htb_leaf_del_last(struct mlx5e_priv *priv, u16 classid, bool force,
struct netlink_ext_ack *extack);
int mlx5e_htb_node_modify(struct mlx5e_priv *priv, u16 classid, u64 rate, u64 ceil,

3
drivers/net/ethernet/mellanox/mlx5/core/en_main.c
View File

@ -3000,8 +3000,7 @@ static int mlx5e_setup_tc_htb(struct mlx5e_priv *priv, struct tc_htb_qopt_offloa
return mlx5e_htb_leaf_to_inner(priv, htb->parent_classid, htb->classid,
htb->rate, htb->ceil, htb->extack);
case TC_HTB_LEAF_DEL:
return mlx5e_htb_leaf_del(priv, htb->classid, &htb->moved_qid, &htb->qid,
htb->extack);
return mlx5e_htb_leaf_del(priv, &htb->classid, htb->extack);
case TC_HTB_LEAF_DEL_LAST:
case TC_HTB_LEAF_DEL_LAST_FORCE:
return mlx5e_htb_leaf_del_last(priv, htb->classid,

3
include/net/pkt_cls.h
View File

@ -816,10 +816,9 @@ enum tc_htb_command {
struct tc_htb_qopt_offload {
struct netlink_ext_ack *extack;
enum tc_htb_command command;
u16 classid;
u32 parent_classid;
u16 classid;
u16 qid;
u16 moved_qid;
u64 rate;
u64 ceil;
};

97
net/sched/sch_htb.c
View File

@ -125,6 +125,7 @@ struct htb_class {
struct htb_class_leaf {
int deficit[TC_HTB_MAXDEPTH];
struct Qdisc *q;
struct netdev_queue *offload_queue;
} leaf;
struct htb_class_inner {
struct htb_prio clprio[TC_HTB_NUMPRIO];
@ -1411,24 +1412,47 @@ htb_graft_helper(struct netdev_queue *dev_queue, struct Qdisc *new_q)
return old_q;
}
static void htb_offload_move_qdisc(struct Qdisc *sch, u16 qid_old, u16 qid_new)
static struct netdev_queue *htb_offload_get_queue(struct htb_class *cl)
{
struct netdev_queue *queue;
queue = cl->leaf.offload_queue;
if (!(cl->leaf.q->flags & TCQ_F_BUILTIN))
WARN_ON(cl->leaf.q->dev_queue != queue);
return queue;
}
static void htb_offload_move_qdisc(struct Qdisc *sch, struct htb_class *cl_old,
struct htb_class *cl_new, bool destroying)
{
struct netdev_queue *queue_old, *queue_new;
struct net_device *dev = qdisc_dev(sch);
struct Qdisc *qdisc;
queue_old = netdev_get_tx_queue(dev, qid_old);
queue_new = netdev_get_tx_queue(dev, qid_new);
queue_old = htb_offload_get_queue(cl_old);
queue_new = htb_offload_get_queue(cl_new);
if (dev->flags & IFF_UP)
dev_deactivate(dev);
qdisc = dev_graft_qdisc(queue_old, NULL);
qdisc->dev_queue = queue_new;
qdisc = dev_graft_qdisc(queue_new, qdisc);
if (dev->flags & IFF_UP)
dev_activate(dev);
if (!destroying) {
struct Qdisc *qdisc;
WARN_ON(!(qdisc->flags & TCQ_F_BUILTIN));
if (dev->flags & IFF_UP)
dev_deactivate(dev);
qdisc = dev_graft_qdisc(queue_old, NULL);
WARN_ON(qdisc != cl_old->leaf.q);
}
if (!(cl_old->leaf.q->flags & TCQ_F_BUILTIN))
cl_old->leaf.q->dev_queue = queue_new;
cl_old->leaf.offload_queue = queue_new;
if (!destroying) {
struct Qdisc *qdisc;
qdisc = dev_graft_qdisc(queue_new, cl_old->leaf.q);
if (dev->flags & IFF_UP)
dev_activate(dev);
WARN_ON(!(qdisc->flags & TCQ_F_BUILTIN));
}
}
static int htb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
@ -1442,10 +1466,8 @@ static int htb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
if (cl->level)
return -EINVAL;
if (q->offload) {
dev_queue = new->dev_queue;
WARN_ON(dev_queue != cl->leaf.q->dev_queue);
}
if (q->offload)
dev_queue = htb_offload_get_queue(cl);
if (!new) {
new = qdisc_create_dflt(dev_queue, &pfifo_qdisc_ops,
@ -1514,6 +1536,8 @@ static void htb_parent_to_leaf(struct Qdisc *sch, struct htb_class *cl,
parent->ctokens = parent->cbuffer;
parent->t_c = ktime_get_ns();
parent->cmode = HTB_CAN_SEND;
if (q->offload)
parent->leaf.offload_queue = cl->leaf.offload_queue;
}
static void htb_parent_to_leaf_offload(struct Qdisc *sch,
@ -1534,6 +1558,7 @@ static int htb_destroy_class_offload(struct Qdisc *sch, struct htb_class *cl,
struct netlink_ext_ack *extack)
{
struct tc_htb_qopt_offload offload_opt;
struct netdev_queue *dev_queue;
struct Qdisc *q = cl->leaf.q;
struct Qdisc *old = NULL;
int err;
@ -1542,16 +1567,15 @@ static int htb_destroy_class_offload(struct Qdisc *sch, struct htb_class *cl,
return -EINVAL;
WARN_ON(!q);
if (!destroying) {
/* On destroy of HTB, two cases are possible:
* 1. q is a normal qdisc, but q->dev_queue has noop qdisc.
* 2. q is a noop qdisc (for nodes that were inner),
* q->dev_queue is noop_netdev_queue.
dev_queue = htb_offload_get_queue(cl);
old = htb_graft_helper(dev_queue, NULL);
if (destroying)
/* Before HTB is destroyed, the kernel grafts noop_qdisc to
* all queues.
*/
old = htb_graft_helper(q->dev_queue, NULL);
WARN_ON(!old);
WARN_ON(!(old->flags & TCQ_F_BUILTIN));
else
WARN_ON(old != q);
}
if (cl->parent) {
cl->parent->bstats_bias.bytes += q->bstats.bytes;
@ -1570,18 +1594,17 @@ static int htb_destroy_class_offload(struct Qdisc *sch, struct htb_class *cl,
if (!err || destroying)
qdisc_put(old);
else
htb_graft_helper(q->dev_queue, old);
htb_graft_helper(dev_queue, old);
if (last_child)
return err;
if (!err && offload_opt.moved_qid != 0) {
if (destroying)
q->dev_queue = netdev_get_tx_queue(qdisc_dev(sch),
offload_opt.qid);
else
htb_offload_move_qdisc(sch, offload_opt.moved_qid,
offload_opt.qid);
if (!err && offload_opt.classid != TC_H_MIN(cl->common.classid)) {
u32 classid = TC_H_MAJ(sch->handle) |
TC_H_MIN(offload_opt.classid);
struct htb_class *moved_cl = htb_find(classid, sch);
htb_offload_move_qdisc(sch, moved_cl, cl, destroying);
}
return err;
@ -1704,9 +1727,11 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg,
}
if (last_child) {
struct netdev_queue *dev_queue;
struct netdev_queue *dev_queue = sch->dev_queue;
if (q->offload)
dev_queue = htb_offload_get_queue(cl);
dev_queue = q->offload ? cl->leaf.q->dev_queue : sch->dev_queue;
new_q = qdisc_create_dflt(dev_queue, &pfifo_qdisc_ops,
cl->parent->common.classid,
NULL);
@ -1878,7 +1903,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
}
dev_queue = netdev_get_tx_queue(dev, offload_opt.qid);
} else { /* First child. */
dev_queue = parent->leaf.q->dev_queue;
dev_queue = htb_offload_get_queue(parent);
old_q = htb_graft_helper(dev_queue, NULL);
WARN_ON(old_q != parent->leaf.q);
offload_opt = (struct tc_htb_qopt_offload) {
@ -1935,6 +1960,8 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
/* leaf (we) needs elementary qdisc */
cl->leaf.q = new_q ? new_q : &noop_qdisc;
if (q->offload)
cl->leaf.offload_queue = dev_queue;
cl->parent = parent;