linux-kernel - Re: [PATCH] zram: check compressor name before setting it

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Date:	Fri, 22 May 2015 22:14:47 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Marcin Jabrzyk <m.jabrzyk@...sung.com>, ngupta@...are.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	kyungmin.park@...sung.com
Subject: Re: [PATCH] zram: check compressor name before setting it

Hello Sergey,

On Fri, May 22, 2015 at 09:44:11PM +0900, Sergey Senozhatsky wrote:
> On (05/22/15 11:12), Marcin Jabrzyk wrote:
> > >
> > >no.
> > >
> > >zram already complains about failed comp backend creation.
> > >it's in dmesg (or syslog, etc.):
> > >
> > >	"zram: Cannot initialise %s compressing backend"
> > >
> > OK, now I see that. Sorry for the noise.
> > 
> > >second, there is not much value in exposing zcomp internals,
> > >especially when the result is just another line in dmesg output.
> > 
> > From the other hand, the only valid values that can be written are
> > in 'comp_algorithm'.
> > So when writing other one, returning -EINVAL seems to be reasonable.
> > The user would get immediately information that he can't do that,
> > now the information can be very deferred in time.
> 
> it's not.
> the error message appears in syslog right before we return -EINVAL
> back to user.

Although Marcin's description is rather misleading, I like the patch.
Every admin doesn't watch dmesg output. Even people could change loglevel
simply so KERN_INFO would be void in that case.

Instant error propagation is more strighforward for user point of view
rather than delaying with depending on another event.

Thanks.

> 
> 	-ss
> 
> > I'm not for exposing more internals, but getting -EINVAL would be nice I

-- 
Kind regards,
Minchan Kim
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