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Subject: Re: [PATCH] livepatch: fix race between enabled_store() and
 klp_unregister_patch()
To: Josh Poimboeuf <jpoimboe@redhat.com>, Li Bin <huawei.libin@huawei.com>
References: <1448855677-8392-1-git-send-email-huawei.libin@huawei.com>
 <20151201011139.GB12513@treble.redhat.com>
Cc: sjenning@redhat.com, jikos@kernel.org, vojtech@suse.com,
        live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
        guohanjun@huawei.com, dingtianhong@huawei.com, xiexiuqi@huawei.com,
        zhouchengming1@huawei.com, Miroslav Benes <mbenes@suse.cz>
From: Jiri Slaby <jslaby@suse.cz>
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Date: Tue, 1 Dec 2015 09:50:23 +0100
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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