linux-kernel - Re: [PATCH] zram: check comp algorithm availability earlier

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Message-ID: <20150527055320.GA3928@swordfish>
Date:	Wed, 27 May 2015 14:53:20 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Marcin Jabrzyk <m.jabrzyk@...sung.com>,
	Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCH] zram: check comp algorithm availability earlier

On (05/27/15 12:51), Minchan Kim wrote:
[..]
> > @@ -378,6 +378,12 @@ static ssize_t comp_algorithm_store(struct device *dev,
> >  	if (sz > 0 && zram->compressor[sz - 1] == '\n')
> >  		zram->compressor[sz - 1] = 0x00;
> >  
> > +	if (!zcomp_available_algorithm(zram->compressor)) {
> > +		pr_err("Error: unavailable compression algorithm: %s\n",
> > +				zram->compressor);
> > +		len = -EINVAL;
> > +	}
> > +
> 
> I'm not against this patch because it's better than old.
> But let's think more about the pr_err part.
> 
> If user try to set wrong algo name, he can see EINVAL.
> Isn't it enough?
> 
> I think every sane admin can think he passed wrong argument
> if he sees -EINVAL.
> So, I don't think we need to emit pr_err in here.
> 

well, it's here simply to make failure investigation easier.
one surely will know that supplied string was not recognized
as a compression algorithm name, but what was it.. "$3 instead
of $2... or, wait, did $i contain something wrong?". zram knew
what was wrong.

/* and you asked to put this warn here in your previous email. */


sure, can remove it.


> The reason I am paranoid about that is that I really don't want
> to argue with syslog info which is part of ABI or not in future.
> If possible, I don't want to depend on pr_xxx.
> 

just for the record...  I don't understand this part.


ok. I'll resend later today.

	-ss
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