linux-kernel - Re: [PATCH 03/14] resource: add walk_system_ram_res

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Date:   Fri, 25 Aug 2017 09:50:07 +0900
From:   AKASHI Takahiro <takahiro.akashi@...aro.org>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>,
        David Howells <dhowells@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Dave Young <dyoung@...hat.com>, Baoquan He <bhe@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 03/14] resource: add walk_system_ram_res_rev()

On Thu, Aug 24, 2017 at 10:06:28AM +0100, Ard Biesheuvel wrote:
> On 24 August 2017 at 09:18, AKASHI Takahiro <takahiro.akashi@...aro.org> wrote:
> > +       /* create a list */
> > +       rams = vmalloc(sizeof(struct resource) * count);
> > +       if (!rams)
> > +               return ret;
> > +
> > +       res.start = start;
> > +       res.end = end;
> > +       res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> > +       orig_end = res.end;
> > +       i = 0;
> > +       while ((res.start < res.end) &&
> > +               (!find_next_iomem_res(&res, IORES_DESC_NONE, true))) {
> > +               if (i >= count) {
> > +                       /* unlikely but */
> > +                       vfree(rams);
> > +                       count += 16;
> 
> If the count is likely to be < 16, why are we using vmalloc() here?

Ah, you're right :)

-Takahiro AKASHI