sch_htb: Fix inconsistency when leaf qdisc creation fails
[ Upstream commit ca49bfd9 ] 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: d03b195b ("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> Signed-off-by:
Sasha Levin <sashal@kernel.org>
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