linux-kernel - Re: [PATCH v3 next 05/10] lib: Add tests for mul_u64_u64_div_u64

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Message-ID: <q168q017-9p30-69p2-o4o5-s6q1s1385o27@syhkavp.arg>
Date: Tue, 17 Jun 2025 00:30:17 -0400 (EDT)
From: Nicolas Pitre <nico@...xnic.net>
To: David Laight <david.laight.linux@...il.com>
cc: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, 
    u.kleine-koenig@...libre.com, Oleg Nesterov <oleg@...hat.com>, 
    Peter Zijlstra <peterz@...radead.org>, 
    Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v3 next 05/10] lib: Add tests for
 mul_u64_u64_div_u64_roundup()

On Sat, 14 Jun 2025, David Laight wrote:

> Replicate the existing mul_u64_u64_div_u64() test cases with round up.
> Update the shell script that verifies the table, remove the comment
> markers so that it can be directly pasted into a shell.
> 
> Rename the divisor from 'c' to 'd' to match mul_u64_add_u64_div_u64().
> 
> It any tests fail then fail the module load with -EINVAL.
> 
> Signed-off-by: David Laight <david.laight.linux@...il.com>

I must withdraw my Reviewed-by here.

>  /*
>   * The above table can be verified with the following shell script:
> - *
> - * #!/bin/sh
> - * sed -ne 's/^{ \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\) },$/\1 \2 \3 \4/p' \
> - *     lib/math/test_mul_u64_u64_div_u64.c |
> - * while read a b c r; do
> - *   expected=$( printf "obase=16; ibase=16; %X * %X / %X\n" $a $b $c | bc )
> - *   given=$( printf "%X\n" $r )
> - *   if [ "$expected" = "$given" ]; then
> - *     echo "$a * $b / $c = $r OK"
> - *   else
> - *     echo "$a * $b / $c = $r is wrong" >&2
> - *     echo "should be equivalent to 0x$expected" >&2
> - *     exit 1
> - *   fi
> - * done
> +
> +#!/bin/sh
> +sed -ne 's/^{ \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\) },$/\1 \2 \3 \4 \5/p' \
> +    lib/math/test_mul_u64_u64_div_u64.c |
> +while read a b d r d; do

This "read a b d r d" is wrong and that breaks the script.


Nicolas