diff options
authorWANG Cong <xiyou.wangcong@gmail.com>2015-05-26 16:08:48 -0700
committerDavid S. Miller <davem@davemloft.net>2015-05-27 14:09:55 -0400
commit86e363dc3b50bfd50a1f315934583fbda673ab8d (patch)
parentad0681185770716523c81b156c44b9804d7b8ed2 (diff)
net_sched: invoke ->attach() after setting dev->qdisc
For mq qdisc, we add per tx queue qdisc to root qdisc for display purpose, however, that happens too early, before the new dev->qdisc is finally set, this causes q->list points to an old root qdisc which is going to be freed right before assigning with a new one. Fix this by moving ->attach() after setting dev->qdisc. For the record, this fixes the following crash: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 975 at lib/list_debug.c:59 __list_del_entry+0x5a/0x98() list_del corruption. prev->next should be ffff8800d1998ae8, but was 6b6b6b6b6b6b6b6b CPU: 1 PID: 975 Comm: tc Not tainted 4.1.0-rc4+ #1019 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000009 ffff8800d73fb928 ffffffff81a44e7f 0000000047574756 ffff8800d73fb978 ffff8800d73fb968 ffffffff810790da ffff8800cfc4cd20 ffffffff814e725b ffff8800d1998ae8 ffffffff82381250 0000000000000000 Call Trace: [<ffffffff81a44e7f>] dump_stack+0x4c/0x65 [<ffffffff810790da>] warn_slowpath_common+0x9c/0xb6 [<ffffffff814e725b>] ? __list_del_entry+0x5a/0x98 [<ffffffff81079162>] warn_slowpath_fmt+0x46/0x48 [<ffffffff81820eb0>] ? dev_graft_qdisc+0x5e/0x6a [<ffffffff814e725b>] __list_del_entry+0x5a/0x98 [<ffffffff814e72a7>] list_del+0xe/0x2d [<ffffffff81822f05>] qdisc_list_del+0x1e/0x20 [<ffffffff81820cd1>] qdisc_destroy+0x30/0xd6 [<ffffffff81822676>] qdisc_graft+0x11d/0x243 [<ffffffff818233c1>] tc_get_qdisc+0x1a6/0x1d4 [<ffffffff810b5eaf>] ? mark_lock+0x2e/0x226 [<ffffffff817ff8f5>] rtnetlink_rcv_msg+0x181/0x194 [<ffffffff817ff72e>] ? rtnl_lock+0x17/0x19 [<ffffffff817ff72e>] ? rtnl_lock+0x17/0x19 [<ffffffff817ff774>] ? __rtnl_unlock+0x17/0x17 [<ffffffff81855dc6>] netlink_rcv_skb+0x4d/0x93 [<ffffffff817ff756>] rtnetlink_rcv+0x26/0x2d [<ffffffff818544b2>] netlink_unicast+0xcb/0x150 [<ffffffff81161db9>] ? might_fault+0x59/0xa9 [<ffffffff81854f78>] netlink_sendmsg+0x4fa/0x51c [<ffffffff817d6e09>] sock_sendmsg_nosec+0x12/0x1d [<ffffffff817d8967>] sock_sendmsg+0x29/0x2e [<ffffffff817d8cf3>] ___sys_sendmsg+0x1b4/0x23a [<ffffffff8100a1b8>] ? native_sched_clock+0x35/0x37 [<ffffffff810a1d83>] ? sched_clock_local+0x12/0x72 [<ffffffff810a1fd4>] ? sched_clock_cpu+0x9e/0xb7 [<ffffffff810def2a>] ? current_kernel_time+0xe/0x32 [<ffffffff810b4bc5>] ? lock_release_holdtime.part.29+0x71/0x7f [<ffffffff810ddebf>] ? read_seqcount_begin.constprop.27+0x5f/0x76 [<ffffffff810b6292>] ? trace_hardirqs_on_caller+0x17d/0x199 [<ffffffff811b14d5>] ? __fget_light+0x50/0x78 [<ffffffff817d9808>] __sys_sendmsg+0x42/0x60 [<ffffffff817d9838>] SyS_sendmsg+0x12/0x1c [<ffffffff81a50e97>] system_call_fastpath+0x12/0x6f ---[ end trace ef29d3fb28e97ae7 ]--- For long term, we probably need to clean up the qdisc_graft() code in case it hides other bugs like this. Fixes: 95dc19299f74 ("pkt_sched: give visibility to mq slave qdiscs") Cc: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 6 insertions, 4 deletions
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index ad9eed70bc8f..1e1c89e51a11 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -815,10 +815,8 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
if (dev->flags & IFF_UP)
- if (new && new->ops->attach) {
- new->ops->attach(new);
- num_q = 0;
- }
+ if (new && new->ops->attach)
+ goto skip;
for (i = 0; i < num_q; i++) {
struct netdev_queue *dev_queue = dev_ingress_queue(dev);
@@ -834,12 +832,16 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
if (!ingress) {
notify_and_destroy(net, skb, n, classid,
dev->qdisc, new);
if (new && !new->ops->attach)
dev->qdisc = new ? : &noop_qdisc;
+ if (new && new->ops->attach)
+ new->ops->attach(new);
} else {
notify_and_destroy(net, skb, n, classid, old, new);