linux-kernel - Re: [PATCH 2/2] zram: user per-cpu compression streams

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Message-ID: <20160503054442.GB25545@swordfish>
Date:	Tue, 3 May 2016 14:44:42 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] zram: user per-cpu compression streams

On (05/03/16 14:23), Minchan Kim wrote:
[..]
> > -	zram->max_comp_streams = num;
> > -	ret = len;
> > -out:
> > -	up_write(&zram->init_lock);
> > -	return ret;
> 
> At least, we need sanity check code, still?
> Otherwise, user can echo "garbage" > /sys/xxx/max_comp_stream" and then
> cat /sys/xxx/max_comp_stream returns num_online_cpus.

hm, I couldn't find any reason to keep the check. we completely
ignore the value anyway, cat /sys/xxx/max_comp_stream will always
return num_online_cpus(), regardless the correctness of supplied
data; `garbage', `2', `1024', `32' make no difference.

	-ss