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From: David Miller <davem@davemloft.net>
To: rshearma@brocade.com
Cc: netdev@vger.kernel.org, tom@herbertland.com,
	roopa@cumulusnetworks.com, david.lebrun@uclouvain.be,
	tgraf@suug.ch, dsa@cumulusnetworks.com
Subject: Re: [PATCH net v2 2/2] lwtunnel: Fix oops on state free after encap module unload
Date: Mon, 23 Jan 2017 15:42:48 -0500 (EST)	[thread overview]
Message-ID: <20170123.154248.261820530578170635.davem@davemloft.net> (raw)
In-Reply-To: <1484958086-6151-3-git-send-email-rshearma@brocade.com>

From: Robert Shearman <rshearma@brocade.com>
Date: Sat, 21 Jan 2017 00:21:26 +0000

> @@ -115,8 +115,12 @@ int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
>  	ret = -EOPNOTSUPP;
>  	rcu_read_lock();

Here 'ret' equals -EOPNOTSUPP

>  	ops = rcu_dereference(lwtun_encaps[encap_type]);
> -	if (likely(ops && ops->build_state))
> -		ret = ops->build_state(dev, encap, family, cfg, lws);
> +	if (likely(ops)) {
> +		if (likely(try_module_get(ops->owner) && ops->build_state))
> +			ret = ops->build_state(dev, encap, family, cfg, lws);
> +		if (ret)
> +			module_put(ops->owner);

If try_module_get() fails, 'ret' will still be -EOPNOTSUPP and we will
module_put() on a module we did not grab a reference to.

I think you need to adjust the logic here.  You only want to 'put' if
try_module_get() succeeds and ->build_state() returns an error.

  reply	other threads:[~2017-01-23 20:42 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-18 15:32 [PATCH net 0/2] net: Fix oops on state free after lwt module unload Robert Shearman
2017-01-18 15:32 ` [PATCH net 1/2] lwtunnel: Fix oops on state free after encap " Robert Shearman
2017-01-18 15:32 ` [PATCH net 2/2] ila: Fix memory leak of lwt dst cache on " Robert Shearman
2017-01-20 17:03 ` [PATCH net 0/2] net: Fix oops on state free after lwt " David Miller
2017-01-20 20:21   ` Robert Shearman
2017-01-21  0:21 ` [PATCH net v2 " Robert Shearman
2017-01-21  0:21   ` [PATCH net v2 1/2] net: Specify the owning module for lwtunnel ops Robert Shearman
2017-01-21  0:21   ` [PATCH net v2 2/2] lwtunnel: Fix oops on state free after encap module unload Robert Shearman
2017-01-23 20:42     ` David Miller [this message]
2017-01-24 16:26       ` Robert Shearman
2017-01-24 16:26   ` [PATCH net v3 0/2] net: Fix oops on state free after lwt " Robert Shearman
2017-01-24 16:26     ` [PATCH net v3 1/2] net: Specify the owning module for lwtunnel ops Robert Shearman
2017-01-24 16:26     ` [PATCH net v3 2/2] lwtunnel: Fix oops on state free after encap module unload Robert Shearman
2017-01-24 21:21     ` [PATCH net v3 0/2] net: Fix oops on state free after lwt " David Miller

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