Messages in this thread Patch in this message | | | From | Vladimir Oltean <> | Subject | [PATCH v2 net-next 3/7] net/sched: taprio: use rtnl_dereference for oper and admin sched in taprio_destroy() | Date | Thu, 15 Sep 2022 13:50:42 +0300 |
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Sparse complains that taprio_destroy() dereferences q->oper_sched and q->admin_sched without rcu_dereference(), since they are marked as __rcu in the taprio private structure.
1671:28: warning: incorrect type in argument 1 (different address spaces) 1671:28: expected struct callback_head *head 1671:28: got struct callback_head [noderef] __rcu * 1674:28: warning: incorrect type in argument 1 (different address spaces) 1674:28: expected struct callback_head *head 1674:28: got struct callback_head [noderef] __rcu *
To silence that build warning, do actually use rtnl_dereference(), since we know the rtnl_mutex is held at the time of q->destroy().
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- v1->v2: resend to net-next, use rtnl_dereference() instead of opening an rcu_read_lock()
net/sched/sch_taprio.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 63cbf856894a..6113c6646559 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -1636,6 +1636,7 @@ static void taprio_destroy(struct Qdisc *sch) { struct taprio_sched *q = qdisc_priv(sch); struct net_device *dev = qdisc_dev(sch); + struct sched_gate_list *oper, *admin; unsigned int i; spin_lock(&taprio_list_lock); @@ -1659,11 +1660,14 @@ static void taprio_destroy(struct Qdisc *sch) netdev_reset_tc(dev); - if (q->oper_sched) - call_rcu(&q->oper_sched->rcu, taprio_free_sched_cb); + oper = rtnl_dereference(q->oper_sched); + admin = rtnl_dereference(q->admin_sched); + + if (oper) + call_rcu(&oper->rcu, taprio_free_sched_cb); - if (q->admin_sched) - call_rcu(&q->admin_sched->rcu, taprio_free_sched_cb); + if (admin) + call_rcu(&admin->rcu, taprio_free_sched_cb); } static int taprio_init(struct Qdisc *sch, struct nlattr *opt, -- 2.34.1
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