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net: sched: Add multi-queue support to sch_tree_lock

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The existing qdiscs that set TCQ_F_MQROOT don't use sch_tree_lock.
However, hardware-offloaded HTB will start setting this flag while also
using sch_tree_lock.

The current implementation of sch_tree_lock basically locks on
qdisc->dev_queue->qdisc, and it works fine when the tree is attached to
some queue. However, it's not the case for MQROOT qdiscs: such a qdisc
is the root itself, and its dev_queue just points to queue 0, while not
actually being used, because there are real per-queue qdiscs.

This patch changes the logic of sch_tree_lock and sch_tree_unlock to
lock the qdisc itself if it's the MQROOT.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Maxim Mikityanskiy 2021-01-19 14:08:11 +02:00 committed by Jakub Kicinski
parent 04a886372a
commit ca1e4ab199
1 changed files with 10 additions and 4 deletions
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14
include/net/sch_generic.h
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@ -552,14 +552,20 @@ static inline struct net_device *qdisc_dev(const struct Qdisc *qdisc)
return qdisc->dev_queue->dev;
}
static inline void sch_tree_lock(const struct Qdisc *q)
static inline void sch_tree_lock(struct Qdisc *q)
{
spin_lock_bh(qdisc_root_sleeping_lock(q));
if (q->flags & TCQ_F_MQROOT)
spin_lock_bh(qdisc_lock(q));
else
spin_lock_bh(qdisc_root_sleeping_lock(q));
}
static inline void sch_tree_unlock(const struct Qdisc *q)
static inline void sch_tree_unlock(struct Qdisc *q)
{
spin_unlock_bh(qdisc_root_sleeping_lock(q));
if (q->flags & TCQ_F_MQROOT)
spin_unlock_bh(qdisc_lock(q));
else
spin_unlock_bh(qdisc_root_sleeping_lock(q));
}
extern struct Qdisc noop_qdisc;