Date: Wed, 17 Jun 2015 10:13:07 +0200 (CEST)
From: Miroslav Benes <mbenes@suse.cz>
To: Li Bin <huawei.libin@huawei.com>
cc: Josh Poimboeuf <jpoimboe@redhat.com>, Seth Jennings <sjenning@redhat.com>,
        Jiri Kosina <jkosina@suse.cz>, Vojtech Pavlik <vojtech@suse.cz>,
        live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
        xiexiuqi@huawei.com
Subject: Re: [PATCH] livepatch: add sysfs interface
 /sys/kernel/livepatch/state
In-Reply-To: <1434522671-31951-1-git-send-email-huawei.libin@huawei.com>
Message-ID: <alpine.LNX.2.00.1506171012440.19134@pobox.suse.cz>
References: <1434522671-31951-1-git-send-email-huawei.libin@huawei.com>
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On Wed, 17 Jun 2015, Li Bin wrote:

> The added sysfs interface /sys/kernel/livepatch/state is read-only,
> it shows the patches that have been applied, incluing the stack index
> and the state of each patch.
> 
> $ cat /sys/kernel/livepatch/state
> Index	Patch				State
> -----------------------------------------------
> 1	klp_test1			enabled
> 2	klp_test2			enabled
> 3	klp_test3			enabled
> -----------------------------------------------
> 
> $ echo 0 > /sys/kernel/livepatch/klp_test3/enabled
> $ cat /sys/kernel/livepatch/state
> Index	Patch				State
> -----------------------------------------------
> 1	klp_test1			enabled
> 2	klp_test2			enabled
> 3	klp_test3			disabled
> -----------------------------------------------
> 
> Signed-off-by: Li Bin <huawei.libin@huawei.com>
> ---

Hi,

I think we should comply with sysfs policy and keep 'one value per 
attribute' as mentioned in the Documentation/filesystems/sysfs.txt:

"
Attributes should be ASCII text files, preferably with only one value
per file. It is noted that it may not be efficient to contain only one
value per file, so it is socially acceptable to express an array of
values of the same type.

Mixing types, expressing multiple lines of data, and doing fancy
formatting of data is heavily frowned upon. Doing these things may get
you publicly humiliated and your code rewritten without notice.
"
The list of applied patches can be obtained just by 'ls 
/sys/kernel/livepatch' and their state is in enabled attribute in each 
respective patch (no, you cannot obtain the order in the stack).

Thanks,

Miroslav Benes
SUSE Labs
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