From: Jiri Slaby <jslaby@suse.cz>
To: Petr Mladek <pmladek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Li Bin <huawei.libin@huawei.com>,
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>
Subject: Re: [PATCH] livepatch: fix race between enabled_store() and klp_unregister_patch()
Date: Tue, 1 Dec 2015 15:28:19 +0100 [thread overview]
Message-ID: <565DAE83.9020205@suse.cz> (raw)
In-Reply-To: <20151201141323.GB14230@pathway.suse.cz>
On 12/01/2015, 03:13 PM, Petr Mladek wrote:
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -612,7 +612,19 @@ static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,
>
> patch = container_of(kobj, struct klp_patch, kobj);
>
> - mutex_lock(&klp_mutex);
> + /*
> + * Avoid a deadlock with kobject_put(&patch->kobj) that is
> + * called under klp_mutex. Bail out when the patch is not
> + * longer registered.
> + */
> + if (!mutex_trylock(&klp_mutex)) {
This introduces false positives.
Deleting/enabling/disabling/other_op_under_klp_mutex of an unrelated
patch may now cause enabled_store to fail. Hence I don't like this
approach at all.
thanks,
--
js
suse labs
next prev parent reply other threads:[~2015-12-01 14:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-30 3:54 [PATCH] livepatch: fix race between enabled_store() and klp_unregister_patch() Li Bin
2015-11-30 13:53 ` Petr Mladek
2015-12-01 1:11 ` Josh Poimboeuf
2015-12-01 2:46 ` libin
2015-12-01 8:50 ` Jiri Slaby
2015-12-01 14:13 ` Petr Mladek
2015-12-01 14:28 ` Jiri Slaby [this message]
2015-12-01 16:57 ` Petr Mladek
2015-12-01 15:53 ` Josh Poimboeuf
2015-12-15 8:14 ` Miroslav Benes
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