linux-kernel - Re: [PATCH v2] checkpatch: fix false positives in REPEATED

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Date:   Thu, 22 Oct 2020 09:10:59 -0700
From:   Joe Perches <joe@...ches.com>
To:     Aditya Srivastava <yashsri421@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        lukas.bulwahn@...il.com, dwaipayanray1@...il.com
Subject: Re: [PATCH v2] checkpatch: fix false positives in REPEATED_WORD
 warning

On Thu, 2020-10-22 at 20:20 +0530, Aditya Srivastava wrote:
> Presence of hexadecimal address or symbol results in false warning
> message by checkpatch.pl.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -3051,7 +3051,10 @@ sub process {
>  		}
>  
>  # check for repeated words separated by a single space
> -		if ($rawline =~ /^\+/ || $in_commit_log) {
> +# avoid false positive from list command eg, '-rw-r--r-- 1 root root'
> +		if (($rawline =~ /^\+/ || $in_commit_log) &&
> +		$rawline !~ /[bcCdDlMnpPs\?-][rwxsStT-]{9}/) {

Alignment and use \b before and after the regex please.

		if (($rawline =~ /^\+/ || $in_commit_log) &&
		    $rawline !~ /\b[bcCdDlMnpPs\?-][rwxsStT-]{9}\b/) {
> @@ -3065,6 +3068,34 @@ sub process {
>  				next if ($first ne $second);
>  				next if ($first eq 'long');
>  
> +				# avoid repeating hex occurrences like 'ff ff fe 09 ...'
> +				if ($first =~ /\b[0-9a-f]{2,}/) {
> +					# if such sequence occurs more than 4, it is most probably part of some of code
> +					next if ((scalar @hex_seq)>4);
> +					# for hex occurrences which are less than 4
> +					# get first hex word in the line
> +					if ($rawline =~ /\b[0-9a-f]{2,} /) {
> +						my $post_hex_seq = $';
> +
> +						# set suffieciently high default values to avoid ignoring or counting in absence of another
> +						my $non_hex_char_pos = 1000;
> +						my $special_chars_pos = 500;
> +
> +						if ($post_hex_seq =~ /[g-z]+/) {
> +							# first non hex character in post_hex_seq
> +							$non_hex_char_pos = $-[0];
> +						}
> +						if($post_hex_seq =~ /[^a-zA-Z0-9]{2,}/) {
> +							# first occurrence of 2 or more special chars
> +							$special_chars_pos = $-[0];
> +						}

What does all this code actually avoid?