From 49e8ae53700212fbb26302df219922752e81fbd2 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Apr 2024 07:32:45 +0000 Subject: net_sched: sch_hfsc: implement lockless accesses to q->defcls Instead of relying on RTNL, hfsc_dump_qdisc() can use READ_ONCE() annotation, paired with WRITE_ONCE() one in hfsc_change_qdisc(). Use READ_ONCE(q->defcls) in hfsc_classify() to no longer acquire qdisc lock from hfsc_change_qdisc(). Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- net/sched/sch_hfsc.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'net') diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index 4e626df742d7..c287bf8423b4 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -1174,7 +1174,8 @@ hfsc_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) } /* classification failed, try default class */ - cl = hfsc_find_class(TC_H_MAKE(TC_H_MAJ(sch->handle), q->defcls), sch); + cl = hfsc_find_class(TC_H_MAKE(TC_H_MAJ(sch->handle), + READ_ONCE(q->defcls)), sch); if (cl == NULL || cl->level > 0) return NULL; @@ -1443,9 +1444,7 @@ hfsc_change_qdisc(struct Qdisc *sch, struct nlattr *opt, return -EINVAL; qopt = nla_data(opt); - sch_tree_lock(sch); - q->defcls = qopt->defcls; - sch_tree_unlock(sch); + WRITE_ONCE(q->defcls, qopt->defcls); return 0; } @@ -1525,7 +1524,7 @@ hfsc_dump_qdisc(struct Qdisc *sch, struct sk_buff *skb) unsigned char *b = skb_tail_pointer(skb); struct tc_hfsc_qopt qopt; - qopt.defcls = q->defcls; + qopt.defcls = READ_ONCE(q->defcls); if (nla_put(skb, TCA_OPTIONS, sizeof(qopt), &qopt)) goto nla_put_failure; return skb->len; -- cgit v1.2.3