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authorEric Dumazet <edumazet@google.com>2016-06-13 11:33:32 -0700
committerDavid S. Miller <davem@davemloft.net>2016-06-15 12:29:54 -0700
commit3d7c8257d999bdf8fa77ffd9be775c7b58cc7b69 (patch)
treeb6f10468510e1731431371abf4a759cc8f65eb73 /net
parent0c5ddb51e8f7be7170600f95a4ea92e5a32afad8 (diff)
downloadlinux-3d7c8257d999bdf8fa77ffd9be775c7b58cc7b69.tar.gz
net_sched: prio: insure proper transactional behavior
Now prio_init() can return -ENOMEM, it also has to make sure any allocated qdiscs are freed, since the caller (qdisc_create()) wont call ->destroy() handler for us. More generally, we want a transactional behavior for "tc qdisc change ...", so prio_tune() should not make modifications if any error is returned. It means that we must validate parameters and allocate missing qdisc(s) before taking root qdisc lock exactly once, to not leave the prio qdisc in an intermediate state. Fixes: cbdf45116478 ("net_sched: prio: properly report out of memory errors") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/sched/sch_prio.c57
1 files changed, 23 insertions, 34 deletions
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index 071718bccdab..a356450b747b 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -172,8 +172,9 @@ prio_destroy(struct Qdisc *sch)
static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
{
struct prio_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *queues[TCQ_PRIO_BANDS];
+ int oldbands = q->bands, i;
struct tc_prio_qopt *qopt;
- int i;
if (nla_len(opt) < sizeof(*qopt))
return -EINVAL;
@@ -187,54 +188,42 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
return -EINVAL;
}
+ /* Before commit, make sure we can allocate all new qdiscs */
+ for (i = oldbands; i < qopt->bands; i++) {
+ queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
+ TC_H_MAKE(sch->handle, i + 1));
+ if (!queues[i]) {
+ while (i > oldbands)
+ qdisc_destroy(queues[--i]);
+ return -ENOMEM;
+ }
+ }
+
sch_tree_lock(sch);
q->bands = qopt->bands;
memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
- for (i = q->bands; i < TCQ_PRIO_BANDS; i++) {
+ for (i = q->bands; i < oldbands; i++) {
struct Qdisc *child = q->queues[i];
- q->queues[i] = &noop_qdisc;
- if (child != &noop_qdisc) {
- qdisc_tree_reduce_backlog(child, child->q.qlen, child->qstats.backlog);
- qdisc_destroy(child);
- }
- }
- sch_tree_unlock(sch);
- for (i = 0; i < q->bands; i++) {
- struct Qdisc *child;
+ qdisc_tree_reduce_backlog(child, child->q.qlen,
+ child->qstats.backlog);
+ qdisc_destroy(child);
+ }
- if (q->queues[i] != &noop_qdisc)
- continue;
+ for (i = oldbands; i < q->bands; i++)
+ q->queues[i] = queues[i];
- child = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
- TC_H_MAKE(sch->handle, i + 1));
- if (!child)
- return -ENOMEM;
- sch_tree_lock(sch);
- q->queues[i] = child;
- sch_tree_unlock(sch);
- }
+ sch_tree_unlock(sch);
return 0;
}
static int prio_init(struct Qdisc *sch, struct nlattr *opt)
{
- struct prio_sched_data *q = qdisc_priv(sch);
- int i;
-
- for (i = 0; i < TCQ_PRIO_BANDS; i++)
- q->queues[i] = &noop_qdisc;
-
- if (opt == NULL) {
+ if (!opt)
return -EINVAL;
- } else {
- int err;
- if ((err = prio_tune(sch, opt)) != 0)
- return err;
- }
- return 0;
+ return prio_tune(sch, opt);
}
static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)