linux-kernel - Re: [PATCHv4 1/9] zram: Preparation for multi-zcomp support

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Date:   Thu, 3 Nov 2022 11:40:31 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCHv4 1/9] zram: Preparation for multi-zcomp support

On (22/11/02 13:13), Minchan Kim wrote:
[..]
> >  
> > +static void zram_destroy_comps(struct zram *zram)
> > +{
> > +	u32 idx;
> > +
> > +	for (idx = 0; idx < ZRAM_MAX_ZCOMPS; idx++) {
> > +		struct zcomp *comp = zram->comps[idx];
> > +
> > +		zram->comps[idx] = NULL;
> > +		if (IS_ERR_OR_NULL(comp))
> 
> nit:
> 
> Why don't you use just NULL check? I don't see any error setting
> for zram->comps(Maybe later patch? Will keep check)?

A defense measure. zcomp_create() returns err pointer, so here
I check for err and nil just in case (if somehow someday we
accidentally have err values stored in comps). It's cheap and
safer than NULL.