[PATCH net-next 2/2] net: sched: htb: remove redundant resource cleanup in htb_init()

From: Zhengchao Shao
Date: Mon Aug 29 2022 - 20:54:24 EST


If htb_init() fails, qdisc_create() invokes htb_destroy() to clear
resources. Therefore, remove redundant resource cleanup in htb_init().

Signed-off-by: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
---
net/sched/sch_htb.c | 36 +++++++++---------------------------
1 file changed, 9 insertions(+), 27 deletions(-)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index cb5872d22ecf..da75885bbffd 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1102,7 +1102,7 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt,

err = qdisc_class_hash_init(&q->clhash);
if (err < 0)
- goto err_free_direct_qdiscs;
+ return err;

qdisc_skb_head_init(&q->direct_queue);

@@ -1125,8 +1125,7 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt,
qdisc = qdisc_create_dflt(dev_queue, &pfifo_qdisc_ops,
TC_H_MAKE(sch->handle, 0), extack);
if (!qdisc) {
- err = -ENOMEM;
- goto err_free_qdiscs;
+ return -ENOMEM;
}

htb_set_lockdep_class_child(qdisc);
@@ -1144,7 +1143,7 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt,
};
err = htb_offload(dev, &offload_opt);
if (err)
- goto err_free_qdiscs;
+ return err;

/* Defer this assignment, so that htb_destroy skips offload-related
* parts (especially calling ndo_setup_tc) on errors.
@@ -1152,22 +1151,6 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt,
q->offload = true;

return 0;
-
-err_free_qdiscs:
- for (ntx = 0; ntx < q->num_direct_qdiscs && q->direct_qdiscs[ntx];
- ntx++)
- qdisc_put(q->direct_qdiscs[ntx]);
-
- qdisc_class_hash_destroy(&q->clhash);
- /* Prevent use-after-free and double-free when htb_destroy gets called.
- */
- q->clhash.hash = NULL;
- q->clhash.hashsize = 0;
-
-err_free_direct_qdiscs:
- kfree(q->direct_qdiscs);
- q->direct_qdiscs = NULL;
- return err;
}

static void htb_attach_offload(struct Qdisc *sch)
@@ -1690,13 +1673,12 @@ static void htb_destroy(struct Qdisc *sch)
qdisc_class_hash_destroy(&q->clhash);
__qdisc_reset_queue(&q->direct_queue);

- if (!q->offload)
- return;
-
- offload_opt = (struct tc_htb_qopt_offload) {
- .command = TC_HTB_DESTROY,
- };
- htb_offload(dev, &offload_opt);
+ if (q->offload) {
+ offload_opt = (struct tc_htb_qopt_offload) {
+ .command = TC_HTB_DESTROY,
+ };
+ htb_offload(dev, &offload_opt);
+ }

if (!q->direct_qdiscs)
return;
--
2.17.1