linux-kernel - Re: [PATCH 11/16] mm: consolidate the get_user

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Message-ID: <20190621144131.GQ19891@ziepe.ca>
Date:   Fri, 21 Jun 2019 11:41:31 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Christoph Hellwig <hch@....de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        Nicholas Piggin <npiggin@...il.com>,
        Khalid Aziz <khalid.aziz@...cle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linux-mips@...r.kernel.org, linux-sh@...r.kernel.org,
        sparclinux@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-mm@...ck.org, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/16] mm: consolidate the get_user_pages* implementations

On Tue, Jun 11, 2019 at 04:40:57PM +0200, Christoph Hellwig wrote:
> @@ -2168,7 +2221,7 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
>   */
>  static bool gup_fast_permitted(unsigned long start, unsigned long end)
>  {
> -	return true;
> +	return IS_ENABLED(CONFIG_HAVE_FAST_GUP) ? true : false;

The ?: is needed with IS_ENABLED?

>  }
>  #endif

Oh, you fixed the util.c this way instead of the headerfile
#ifdef..

I'd suggest to revise this block a tiny bit:

-#ifndef gup_fast_permitted
+#if !IS_ENABLED(CONFIG_HAVE_FAST_GUP) || !defined(gup_fast_permitted)
 /*
  * Check if it's allowed to use __get_user_pages_fast() for the range, or
  * we need to fall back to the slow version:
  */
-bool gup_fast_permitted(unsigned long start, int nr_pages)
+static bool gup_fast_permitted(unsigned long start, int nr_pages)
 {

Just in case some future arch code mismatches the header and kconfig..

Regards,
Jason