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authorMaxim Mikityanskiy <maximmi@nvidia.com>2021-08-26 14:54:25 +0300
committerJakub Kicinski <kuba@kernel.org>2021-08-30 16:33:59 -0700
commitca49bfd90a9dde175d2929dc1544b54841e33804 (patch)
treec52af23984e7acfb4c82285ca771cb5687be6224 /net
parent1b9fbe813016b08e08b22ddba4ddbf9cb1b04b00 (diff)
sch_htb: Fix inconsistency when leaf qdisc creation fails
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: d03b195b5aa0 ("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>
Diffstat (limited to 'net')
-rw-r--r--net/sched/sch_htb.c97
1 files changed, 62 insertions, 35 deletions
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 81ea8332547a..5067a6e5d4fd 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -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;