linux-kernel - Re: [PATCH] lib/lzo/lzo1x_compress.c: replace ternary operator with min() and min

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Date:   Tue, 19 Jul 2022 16:44:29 +0000
From:   Dave Rodgman <dave.rodgman@....com>
To:     Jonathan Corbet <corbet@....net>,
        Jiangshan Yi <13667453960@....com>
CC:     "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jiangshan Yi <yijiangshan@...inos.cn>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] lib/lzo/lzo1x_compress.c: replace ternary operator with
 min() and min_t()

> From: Jonathan Corbet <corbet@....net>
> Sent: 14 July 2022 14:39
> To: Jiangshan Yi
> Cc: linux-doc@...r.kernel.org; linux-kernel@...r.kernel.org; Jiangshan Yi; Andrew Morton
> Subject: Re: [PATCH] lib/lzo/lzo1x_compress.c: replace ternary operator with min() and min_t()
>
> Jiangshan Yi <13667453960@....com> writes:
>
> > From: Jiangshan Yi <yijiangshan@...inos.cn>
> >
> > Fix the following coccicheck warning:
> >
> > lib/lzo/lzo1x_compress.c:54: WARNING opportunity for min().
> > lib/lzo/lzo1x_compress.c:329: WARNING opportunity for min().
> >
> > min() and min_t() macro is defined in include/linux/minmax.h. It avoids
> > multiple evaluations of the arguments when non-constant and performs
> > strict type-checking.
> >
> > Signed-off-by: Jiangshan Yi <yijiangshan@...inos.cn>
> > ---
> >  lib/lzo/lzo1x_compress.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/lzo/lzo1x_compress.c b/lib/lzo/lzo1x_compress.c
> > index 76758e9296ba..9d31e7126606 100644
> > --- a/lib/lzo/lzo1x_compress.c
> > +++ b/lib/lzo/lzo1x_compress.c
> > @@ -50,9 +50,7 @@ lzo1x_1_do_compress(const unsigned char *in, size_t in_len,
> >
> >               if (dv == 0 && bitstream_version) {
> >                       const unsigned char *ir = ip + 4;
> > -                     const unsigned char *limit = ip_end
> > -                             < (ip + MAX_ZERO_RUN_LENGTH + 1)
> > -                             ? ip_end : ip + MAX_ZERO_RUN_LENGTH + 1;
> > +                     const unsigned char *limit = min(ip_end, ip + MAX_ZERO_RUN_LENGTH + 1);
> >  #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && >       defined(LZO_FAST_64BIT_MEMORY_ACCESS)
> >                       u64 dv64;
> > @@ -326,7 +324,7 @@ static int lzogeneric1x_1_compress(const unsigned char *in, size_t in_len,
> >       data_start = op;
> >
> >       while (l > 20) {
> > -             size_t ll = l <= (m4_max_offset + 1) ? l : (m4_max_offset + 1);
> > +             size_t ll = min_t(size_t, l, m4_max_offset + 1);
> >               uintptr_t ll_end = (uintptr_t) ip + ll;
> >               if ((ll_end + ((t + ll) >> 5)) <= ll_end)
> >                       break;
>
> So these look like good changes to me, but I am not the maintainer of
> this code.  Maybe Andrew (copied) would have a spot for this patch?
>
> Thanks,
>
> jon

This looks good to me. I've given it a quick test and it appears to function properly.

Dave
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