linux-kernel - Re: [PATCH] lib: lz4: fixed zram with lz4 on big endian machines

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Date:	Fri, 8 Apr 2016 13:05:14 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Rui Salvaterra <rsalvaterra@...il.com>
Cc:	Chanho Min <chanho.min@....com>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	eunb.song@...sung.com, linux-kernel@...r.kernel.org,
	kyungsik.lee@....com, stable@...r.kernel.org, minchan@...nel.org,
	sergey.senozhatsky@...il.com, linux-mm@...ck.org
Subject: Re: [PATCH] lib: lz4: fixed zram with lz4 on big endian machines

On Fri, Apr 08, 2016 at 08:51:17PM +0100, Rui Salvaterra wrote:
> 
> On 8 Apr 2016 17:50, "Greg KH" <gregkh@...uxfoundation.org> wrote:
> >
> > On Fri, Apr 08, 2016 at 04:23:24PM +0100, Rui Salvaterra wrote:
> > > Based on Sergey's test patch [1], this fixes zram with lz4 compression on
> big endian cpus. Tested on ppc64 with no regression on x86_64.
> >
> > Please wrap your text at 72 columns in a changelog comment.
> >
> > >
> > > [1] http://marc.info/?l=linux-kernel&m=145994470805853&w=4
> > >
> > > Cc: stable@...r.kernel.org
> > > Signed-off-by: Rui Salvaterra <rsalvaterra@...il.com>
> >
> > Please attribute Sergey here in the signed-off-by area with a
> > "Suggested-by:" type mark
> >
> > > ---
> > >  lib/lz4/lz4defs.h | 29 +++++++++++++++--------------
> > >  1 file changed, 15 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/lib/lz4/lz4defs.h b/lib/lz4/lz4defs.h
> > > index abcecdc..a98c08c 100644
> > > --- a/lib/lz4/lz4defs.h
> > > +++ b/lib/lz4/lz4defs.h
> > > @@ -11,8 +11,7 @@
> > >  /*
> > >   * Detects 64 bits mode
> > >   */
> > > -#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) \
> > > -     || defined(__ppc64__) || defined(__LP64__))
> > > +#if defined(CONFIG_64BIT)
> >
> > This patch seems to do two different things, clean up the #if tests, and
> > change the endian of some calls.  Can you break this up into 2 different
> > patches?
> >
> > thanks,
> >
> > greg k-h
> 
> Hi Greg,
> 
> Thanks for the review (and patience). The 64-bit #if test is actually part of
> the fix, since __ppc64__ isn't defined anywhere and we'd fall into the 32-bit
> definitions for ppc64. I can send the other one separately, for sure. I'll do a
> v2 tomorrow.

Ah, well document that please, it was not obvious at all that this was
required.

thanks,

greg k-h-