linux-kernel - Re: [PATCH] livepatch: fix race between enabled_store() and klp_unregister

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Message-ID: <565D5F4F.8020807@suse.cz>
Date:	Tue, 1 Dec 2015 09:50:23 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Josh Poimboeuf <jpoimboe@...hat.com>,
	Li Bin <huawei.libin@...wei.com>
Cc:	sjenning@...hat.com, jikos@...nel.org, vojtech@...e.com,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
	guohanjun@...wei.com, dingtianhong@...wei.com, xiexiuqi@...wei.com,
	zhouchengming1@...wei.com, Miroslav Benes <mbenes@...e.cz>
Subject: Re: [PATCH] livepatch: fix race between enabled_store() and
 klp_unregister_patch()

On 12/01/2015, 02:11 AM, Josh Poimboeuf wrote:
> When I try to recreate something similar by putting a delay in
> enabled_store(), klp_free_patch() just sleeps on its call to
> kobject_put() until enabled_store() returns.  The unregister stack looks
> like:
> 
>   [<ffffffff812e966b>] __kernfs_remove+0x1fb/0x380
>   [<ffffffff812ea273>] kernfs_remove+0x23/0x40
>   [<ffffffff812ec601>] sysfs_remove_dir+0x51/0x80
>   [<ffffffff81407fb8>] kobject_del+0x18/0x50
>   [<ffffffff8140804a>] kobject_release+0x5a/0x190
>   [<ffffffff81407f27>] kobject_put+0x27/0x50

What about _put outside of klp_mutex in klp_unregister_patch (and maybe
the other _put's as well)? Plus Li Bin's patch.

thanks,
-- 
js
suse labs
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