netdev - Re: [Patch net 2/2] net_sched: always call ->destroy when ->init() fails

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Date:	Sat, 25 Oct 2014 01:44:04 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Cong Wang <cwang@...pensource.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Cong Wang <xiyou.wangcong@...il.com>,
	netdev <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	Wang Bo <wang.bo116@....com.cn>,
	John Fastabend <john.r.fastabend@...el.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Terry Lam <vtlam@...gle.com>
Subject: Re: [Patch net 2/2] net_sched: always call ->destroy when ->init()
 fails

On Fri, Oct 24, 2014 at 05:38:48PM -0700, Cong Wang wrote:
> On Fri, Oct 24, 2014 at 5:36 PM, Patrick McHardy <kaber@...sh.net> wrote:
> >
> > Again, the correct fix is to make qdisc_create_dflt() not call
> > qdisc_destroy() but clean up the qdisc manually as done in
> > qdisc_create().
> 
> I kindly wish you a good luck with fixing all callers of qdisc_create_dflt().
> Go ahead. :)

Here you go:

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index fc04fe9..3a71e51 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -590,18 +590,21 @@ struct Qdisc *qdisc_create_dflt(struct netdev_queue *dev_queue,
 	struct Qdisc *sch;
 
 	if (!try_module_get(ops->owner))
-		goto errout;
+		goto err1;
 
 	sch = qdisc_alloc(dev_queue, ops);
 	if (IS_ERR(sch))
-		goto errout;
+		goto err2;
 	sch->parent = parentid;
 
 	if (!ops->init || ops->init(sch, NULL) == 0)
 		return sch;
 
-	qdisc_destroy(sch);
-errout:
+	dev_put(sch->dev_queue->dev);
+	kfree((char *)sch - sch->padded);
+err2:
+	module_put(ops->owner);
+err1:
 	return NULL;
 }
 EXPORT_SYMBOL(qdisc_create_dflt);
--
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