tree b6f10468510e1731431371abf4a759cc8f65eb73
parent 0c5ddb51e8f7be7170600f95a4ea92e5a32afad8
author Eric Dumazet <edumazet@google.com> 1465842812 -0700
committer David S. Miller <davem@davemloft.net> 1466018994 -0700

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>