Date:   Wed, 15 Feb 2023 17:48:00 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Carlos Llamas <cmllamas@google.com>
Cc:     linux-kernel@vger.kernel.org,
        Cristian Ciocaltea <cristian.ciocaltea@collabora.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Jialu Xu <xujialu@vimux.org>, Vipin Sharma <vipinsh@google.com>
Subject: Re: [PATCH] scripts/tags.sh: fix incompatibility with PCRE2
Message-ID: <Y+0MwIucdhrCVzs8@kroah.com>
References: <Y+snZioVyo82mAUj@kroah.com>
 <20230214204142.1514599-1-cmllamas@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230214204142.1514599-1-cmllamas@google.com>
Precedence: bulk

On Tue, Feb 14, 2023 at 08:41:42PM +0000, Carlos Llamas wrote:
> Starting with release 10.38 PCRE2 drops default support for using \K in
> lookaround patterns as described in [1]. Unfortunately, scripts/tags.sh
> relies on such functionality to collect all_compiled_soures() leading to
> the following error:
> 
>   $ make COMPILED_SOURCE=1 tags
>     GEN     tags
>   grep: \K is not allowed in lookarounds (but see PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK)
> 
> The usage of \K for this pattern was introduced in commit 4f491bb6ea2a
> ("scripts/tags.sh: collect compiled source precisely") which speeds up
> the generation of tags significantly.
> 
> In order to fix this issue without compromising the performance we can
> switch over to an equivalent sed expression. The same matching pattern
> is preserved here except \K is replaced with a backreference \1.
> 
> [1] https://www.pcre.org/current/doc/html/pcre2syntax.html#SEC11
> 
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> Cc: Masahiro Yamada <masahiroy@kernel.org>
> Cc: Jialu Xu <xujialu@vimux.org>
> Cc: Vipin Sharma <vipinsh@google.com>
> Signed-off-by: Carlos Llamas <cmllamas@google.com>
> ---
>  scripts/tags.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Shouldn't this get a "Fixes:" tag with the commit that caused the
problem?  And if this affects older kernels (as it does), it should also
get a cc: stable?

thanks,

greg k-h